Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of May ~~4, 2020,~~3, 2021, the registrant had ~~70,443,933~~74,047,864 shares of common stock, $0.0001 par value per share, outstanding.

	March 31, 2020			December 31, 2019			March 31, 2021			December 31, 2020
Assets
Current assets:
Cash and cash equivalents	$	40,467		$	60,437		$	101,351		$	107,146
Short-term investments		94,637			96,924			1,500			8,005
Receivables from collaborations		976			482			1,028			1,541
Prepaid expenses and other current assets		1,796			1,953			2,630			2,011
Total current assets		137,876			159,796			106,509			118,703
Other assets		558			280
Long-term investments		3,006			—
Restricted cash		440			440			270			440
Property and equipment, net		900			992			617			690
Operating lease right-of-use asset		6,898			7,260			3,261			5,754
Total assets	$	149,678		$	168,768		$	110,657		$	125,587
Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable	$	739		$	2,052		$	1,636		$	1,994
Accrued and other liabilities		15,014			17,572			12,156			16,407
Total current liabilities		15,753			19,624			13,792			18,401
Noncurrent operating lease liability		6,260			6,718			2,707			4,815
Total liabilities		22,013			26,342			16,499			23,216
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.0001 par value, 200,000 shares authorized as of March 31, 2020, and December 31, 2019; 64,687 and 63,514 shares issued and outstanding as of March 31, 2020, and December 31, 2019, respectively		6			6
Common stock, $0.0001 par value, 200,000 shares authorized as of March 31, 2021, and December 31, 2020; 73,884 and 70,686 shares issued and outstanding as of March 31, 2021, and December 31, 2020, respectively								7			7
Additional paid-in capital		438,131			428,479			490,784			478,599
Accumulated deficit		(310,547	)		(286,101	)		(396,633	)		(376,238	)
Accumulated other comprehensive income		75			42			—			3
Total stockholders’ equity		127,665			142,426			94,158			102,371
Total liabilities and stockholders’ equity	$	149,678		$	168,768		$	110,657		$	125,587

							Three Months Ended March 31,
	Three Months Ended March 31,						2021			2020
	2020			2019
Operating expenses:
Research and development	$	20,125		$	20,239		$	15,339		$	20,125
General and administrative		4,946			4,164			5,428			4,946
Total operating expenses		25,071			24,403			20,767			25,071
Loss from operations		(25,071	)		(24,403	)		(20,767	)		(25,071	)
Interest and other income, net		625			716			372			625
Net loss	$	(24,446	)	$	(23,687	)	$	(20,395	)	$	(24,446	)
Net loss per share, basic and diluted	$	(0.38	)	$	(0.61	)	$	(0.28	)	$	(0.38	)
Weighted average common shares used to compute net loss per share, basic and diluted		64,556			38,866			72,247			64,556

	Three Months Ended March 31,						Three Months Ended March 31,
	2020			2019			2021			2020
Net loss	$	(24,446	)	$	(23,687	)	$	(20,395	)	$	(24,446	)
Other comprehensive income:
Net unrealized gain on available-for-sale securities		33			106
Other comprehensive (loss) income:
Net unrealized (loss) gain on available-for-sale securities								(3	)		33
Total comprehensive loss	$	(24,413	)	$	(23,581	)	$	(20,398	)	$	(24,413	)

	Three Months Ended March 31, 2020														Three Months Ended March 31, 2021
	Common Stock														Common Stock
	Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Accumulated Other Comprehensive Income		Total Stockholders' Equity			Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Accumulated Other Comprehensive Income			Total Stockholders' Equity
Balance at December 31, 2019		63,514	$	6	$	428,479	$	(286,101	)	$	42	$	142,426
Balance at December 31, 2020																70,686	$	7	$	478,599	$	(376,238	)	$	3		$	102,371
Issuance of common stock in connection with at-the-market offering, net of underwriting commissions and issuance costs		1,160		—		7,397		—			—		7,397			3,197		—		9,488		—			—			9,488
Exercise of stock options		13		—		262		—			—		262			1		—		2		—			—			2
Stock-based compensation expense		—		—		1,993		—			—		1,993			—		—		2,695		—			—			2,695
Net loss		—		—		—		(24,446	)		—		(24,446	)		—		—		—		(20,395	)		—			(20,395	)
Unrealized gain on available-for-sale securities		—		—		—		—			33		33
Balance at March 31, 2020		64,687	$	6	$	438,131	$	(310,547	)	$	75	$	127,665
Unrealized loss on available-for-sale securities																—		—		—		—			(3	)		(3	)
Balance at March 31, 2021																73,884	$	7	$	490,784	$	(396,633	)	$	—		$	94,158

	Three Months Ended March 31, 2019															Three Months Ended March 31, 2020
	Common Stock															Common Stock
	Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Accumulated Other Comprehensive Loss			Total Stockholders' Equity			Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Accumulated Other Comprehensive Income		Total Stockholders' Equity
Balance at December 31, 2018		38,834	$	4	$	322,993	$	(196,170	)	$	(113	)	$	126,714
Balance at December 31, 2019																	63,514	$	6	$	428,479	$	(286,101	)	$	42	$	142,426
Issuance of common stock in connection with at-the-market offering, net of underwriting commissions and issuance costs		243		—		1,150		—			—			1,150			1,160		—		7,397		—			—		7,397
Exercise of stock options		6		—		8		—			—			8			13		—		262		—			—		262
Stock-based compensation expense		—		—		1,683		—			—			1,683			—		—		1,993		—			—		1,993
Cumulative-effect adjustment from adoption of ASU 2018-07 accounting standard on stock compensation		—		—		71		(71	)		—			—
Net loss		—		—		—		(23,687	)		—			(23,687	)		—		—		—		(24,446	)		—		(24,446	)
Unrealized gain on available-for-sale securities		—		—		—		—			106			106			—		—		—		—			33		33
Balance at March 31, 2019		39,083	$	4	$	325,905	$	(219,928	)	$	(7	)	$	105,974
Balance at March 31, 2020																	64,687	$	6	$	438,131	$	(310,547	)	$	75	$	127,665

	Three Months Ended March 31,						Three Months Ended March 31,
	2020			2019			2021			2020
Cash Flows Used in Operating Activities
Net loss	$	(24,446	)	$	(23,687	)	$	(20,395	)	$	(24,446	)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation		105			125			73			105
Amortization of premiums on investments		(85	)		(210	)
Accretion (amortization) of premiums on investments								3			(85	)
Stock-based compensation		1,993			1,683			2,695			1,993
Gain on remeasurement of the lease liability								(362	)		—
Non-cash lease expense		362			329			351			362
Changes in operating assets and liabilities:
Receivables from collaborations		(494	)		(516	)		513			(494	)
Prepaid expenses and other current assets		231			241			(619	)		231
Other assets		(278	)		(63	)		—			(278	)
Accounts payable		(1,318	)		365			(390	)		(1,318	)
Accrued liabilities		(2,682	)		1,461			(3,402	)		(2,682	)
Lease liability		(403	)		(352	)		(469	)		(403	)
Net cash used in operating activities		(27,015	)		(20,624	)		(22,002	)		(27,015	)

Cash Flows (Used in) Provided by Investing Activities
Cash Flows Provided by (Used in) Investing Activities
Purchases of investments		(57,059	)		(14,104	)		—			(57,059	)
Proceeds from sale and maturity of investments		56,458			23,100			6,500			56,458
Purchases of property and equipment		(13	)		—			—			(13	)
Net cash (used in) provided by investing activities		(614	)		8,996
Net cash provided by (used in) investing activities								6,500			(614	)

Cash Flows Provided by Financing Activities
Proceeds from issuance of common stock through an at-the-market offering, net		7,397			1,146			9,535			7,397
Proceeds from stock option exercises		262			8			2			262
Net cash provided by financing activities		7,659			1,154			9,537			7,659

Net decrease in cash, cash equivalents, and restricted cash		(19,970	)		(10,474	)		(5,965	)		(19,970	)
Cash, cash equivalents, and restricted cash at beginning of period		60,877			51,498			107,586			60,877
Cash, cash equivalents, and restricted cash at end of period	$	40,907		$	41,024		$	101,621		$	40,907

Supplemental Disclosure of Non-Cash Activities:
Unpaid amounts related to stock issuance and deferred financing costs	$	74		$	29		$	47		$	74

Calithera Biosciences, Inc., or the Company, was incorporated in the State of Delaware on March 9, 2010. The Company is a clinical-stage biopharmaceutical company ~~focused on discovering~~pioneering the discovery and ~~developing small molecule drugs~~development of targeted therapies that ~~target novel and critical~~disrupt cellular metabolic pathways into preferentially block tumor cells and ~~cancer-fighting immune cells.~~enhance immune-cell activity. Driven by a commitment to rigorous science and a passion for improving the lives of people impacted by cancer and other life-threatening diseases, Calithera is advancing a pipeline of first-in-clinic, oral therapeutics to meaningfully expand treatment options available to patients. The Company’s principal operations are based in South San Francisco, California, and it operates in ~~one~~1 segment.

The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Calithera Biosciences UK Limited and Calithera Biosciences Ireland Limited. All significant intercompany accounts and transactions have been eliminated from the condensed consolidated financial statements.

In the course of its development activities, the Company has sustained operating losses and expects such losses to continue over the next several years. The Company’s ultimate success depends on the outcome of its research and development activities. The Company has incurred net losses from operations since inception and has an accumulated deficit of $396.6 million as of March 31, 2021. The Company intends to raise additional capital through the issuance of additional equity, and potentially through strategic alliances with partner companies. However, if such financing is not available at adequate levels, the Company will need to reevaluate its operating plans. Management believes that the currently available resources will provide sufficient funds to enable the Company to meet its operating plan for at least the twelve-month period following the filing of the Company’s unaudited consolidated financial statements for the three months ended March 31, 2021, included in the Quarterly Report on Form 10-Q. However, if the Company’s anticipated operating results are not achieved in future periods, management believes that planned expenditures may need to be reduced in order to extend the time period over which the then-available resources would be able to fund the Company’s operations.

The interim condensed consolidated balance sheet as of March 31, ~~2020,~~2021, the statements of operations, comprehensive loss, stockholders’ equity, and cash flows for the three months ended March 31, ~~2020~~2021 and ~~2019,~~2020, are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s condensed consolidated financial statements included in this report. The financial data and the other information disclosed in these notes to the condensed consolidated financial statements related to the three-month periods are also unaudited. The results of operations for the three months ended March 31, ~~2020~~2021 are not necessarily indicative of the results to be expected for the year ending December 31, ~~2020~~2021 or for any other future annual or interim period. The balance sheet as of December 31, ~~2019~~2020 included herein was derived from the audited consolidated financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements included in the Company’s Form 10-K as filed with the Securities and Exchange Commission, or SEC.

The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP. The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contract assets and contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accrued liabilities, revenue recognition, ~~receivables from collaborations,~~ fair value of marketable securities, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.

The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. Cash equivalents, which consist primarily of amounts invested in money market accounts, are stated at fair value.

All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each balance sheet date. As of each balance sheet date, the Company classifies available-for-sale securities with remaining contractual maturities of more than one year as long-term investments, and those with remaining contractual maturities of one year or less as short-term investments. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive ~~income~~ (loss). income. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income, net. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest and other income, net.

Restricted cash consists of money market funds held by the Company’s financial institution as collateral for the Company’s obligations under its facility lease for the Company’s corporate headquarters in South San Francisco, California.

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents, investments and restricted cash. The Company invests in a variety of financial instruments and, by its policy, limits these financial instruments to high credit quality securities issued by the U.S. government, U.S. government-sponsored agencies and highly rated banks and corporations, subject to certain concentration limits. The Company’s cash, cash equivalents, investments and restricted cash are held by financial institutions in the United States that management believes are of high credit quality. Amounts on deposit may at times exceed federally insured limits.

The majority of the Company’s receivables from collaborations are derived from its collaboration and license agreement with Incyte Corporation, or Incyte, as described in Note 10, Collaboration and Licensing Agreements - Incyte Collaboration and LicenseAgreement.

The Company records revenue in accordance with Accounting Standards Codification, or ASC No. 2014-09, Revenue from Contracts with Customers (Topic 606), or ASC 606. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

The Company has a collaboration and license agreement with Incyte, or the Incyte Collaboration Agreement, that is within the scope of ASC 606, under which it licenses certain rights to ~~one~~1 of its product candidates to Incyte Corporation. The terms of this arrangement include payment to the Company of a non-refundable, upfront license fee, and potential development, regulatory and sales milestones, and sales royalties. Each of these payments results in collaboration revenues, except for revenues from royalties on net sales of licensed products, which would be classified as royalty revenues.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreement, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of

the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract.

Licenses of Intellectual Property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promised goods or services, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, upfront fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Milestone Payments: At the inception of each arrangement that includes development, regulatory or commercial milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvalsare received or the underlying activity has been completed. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenue in the period of adjustment.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements.

Upfront payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional.

The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less.

The Company had no0 contract assets or liabilities as of March 31, ~~2020~~2021 and December 31, ~~2019,~~2020, and had no0 changes in contract assets and liabilities during the three months ended March 31, ~~2020~~2021 and ~~2019.~~2020.

The Company records accrued liabilities for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and includes these costs in accrued and other liabilities in the consolidated balance sheets and within research and development expense in the consolidated statements of operations. These costs are a significant component of the Company’s research and development expenses. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers under the service agreements. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. The Company has not experienced any material differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled, and the rate of patient enrollments may vary from the Company’s estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations.

The Company assesses at the inception of award agreements whether the agreement is a liability. If the Company is obligated to repay funds received regardless of the outcome of the related research and development activities, then the Company is required to estimate and recognize a liability for this obligation. Alternatively, if the Company is not required to repay the funds, then payments received are recorded as contra research and development expense in the consolidated statement of operations as expenses are incurred.

Receivables from collaborations represent amounts receivable for which the payment criteria has been met and allowable expenses have been incurred, but not received as of the balance sheet date. Collaboration reimbursement advances represent amounts received for which the allowable expenses have not been incurred as of the balance sheet date.

The Company accounts for its leases under ASU No. 2016-02, Leases (Topic 842), or ASU 842. Operating lease right-of-use, or ROU, assets and lease liabilities are recognized at commencement and are recorded for leases with durations greater than 12 months.

ROU assets represent the Company’s right to use an underlying asset during the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that it will exercise that option. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. The Company estimates an incremental borrowing rate based on the information available at commencement date, in determining the present value of lease payments. The operating lease ROU asset also includes lease incentives. Lease expense is recognized on a straight-line basis over the lease term. The Company elected to not separate lease components and non-lease components for its long-term facility lease. Variable lease payments include lease operating expenses.

The Company maintains various stock incentive plans under which stock options and restricted stock awards are granted to employees, non-employee directors of the board, and non-employees. The Company also has an employee stock purchase plan for all eligible employees. Stock options and stock purchased under the employee stock purchase plan, are recorded at fair value as of the grant date using the Black-Scholes option-pricing model. Restricted stock awards are measured at grant date fair value, at the market price of the Company’s common stock on the grant date. The Company records stock-based compensation expense related to the service-based instruments ratably over the employee, director, or non-employees’ respective requisite service period (generally the vesting period). For performance-based stock awards with vesting conditioned on the achievement of certain strategic milestones, stock-based compensation expense is recognized over the period from the date the performance condition is determined to be probable of occurring through the date the applicable condition is expected to be met. If the performance condition is not considered probable of being achieved, no stock-based compensation expense is recognized until such time as the performance condition is considered probable of being met, if at all. If the assessment of the probability of the performance condition being met changes, the impact of the change in estimate would be recognized in the period of the change.

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period without consideration of common stock equivalents. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive.

In ~~August 2018,~~December 2019, the FASB issued ~~ASU 2018-13, Fair Value Measurement~~Accounting Standards Update (“ASU”) No. 2019-12, Income Taxes (Topic ~~820)~~740): ~~Disclosure Framework-Changes~~Simplifying the Accounting for Income Taxes, which removes certain exceptions and amends certain requirements in the existing income tax guidance to ~~the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements on fair value measurements.~~ease accounting requirements. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, ~~2019,~~2020 and ~~interim periods therein.~~must be applied on a retrospective basis. The Company adopted this guidance effective January 1, ~~2020.~~ ~~The adoption of this guidance did not have a significant~~2021 and there was no impact on ~~the Company’s disclosures.~~

~~In November 2018, the FASB issued ASU 2018-18—Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606,~~ or ASU 2018-18. This standard provides guidance on the interaction between Revenue Recognition (Topic 606) and Collaborative Arrangements (Topic 808) by aligning the unit of account guidance between the two topics and clarifying whether certain transactions between collaborative participants should be accounted for as revenue under Topic 606. ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted this guidance effective on January 1, 2020. The adoption did not have a significant impact on the Company’sits consolidated financial statements and ~~related~~ disclosures.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU 2016-13. The updated accounting guidance requires changes to the recognition of credit losses on financial instruments not accounted for at fair value through net income. In May 2019, the FASB issued ASU No. 2019-05, Targeted Transition Relief, which provides transition guidance to entities that elect the fair value option for eligible instruments. In November 2019, the FASB issued ASU 2019-10 which extends the effective date of the standards for smaller reporting companies to interim and annual periods beginning after December 15, 2022. These standards require using a modified retrospective approach with the cumulative effect recognized as an adjustment to retained earnings. A prospective transition approach is required for debt securities that have recognized an other-than-temporary impairment prior to the effective date. For the Company’s receivables from collaborations and certain other financial instruments, the Company will be required to use a forward-looking “expected” credit loss model instead of the existing “incurred” credit loss model, which will generally result in earlier recognition of allowances for credit losses. The Company plans to adopt this standard effective January 1, 2023. The Company is currently evaluating the effect the guidance will have on its financial statements or disclosures.

Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the condensed consolidated financial statements on a recurring basis (at least annually). Financial instruments include cash and cash equivalents, investments, receivables from collaborations, accounts payable, and accrued liabilities that approximate fair value due to their relatively short maturities.

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3—Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.

A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Where quoted prices are available in an active market, securities are classified as Level 1. The Company classifies money market funds as Level 1. When quoted market prices are not available for the specific security, then the Company estimates fair value by using quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes and market reference data. The Company classifies its corporate notes and U.S. government agency securities as Level 2. Level 2 inputs for the valuations are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset or liability.

The following table sets forth the fair value of our financial assets and liabilities, allocated into Level 1, Level 2 and Level 3, that were measured on a recurring basis (in thousands):

	March 31, 2020								March 31, 2021
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	26,059	$	—	$	—	$	26,059	$	100,579	$	—	$	—	$	100,579
Corporate notes and commercial paper		—		74,495		—		74,495
U.S. treasury securities		—		28,527		—		28,527
U.S. government agency securities		—		9,010		—		9,010		—		1,500		—		1,500
Total financial assets	$	26,059	$	112,032	$	—	$	138,091	$	100,579	$	1,500	$	—	$	102,079

	December 31, 2019								December 31, 2020
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	45,743	$	—	$	—	$	45,743	$	106,782	$	—	$	—	$	106,782
Corporate notes and commercial paper		—		55,770		—		55,770		—		6,502		—		6,502
U.S. treasury securities		—		38,739		—		38,739
U.S. government agency securities		—		16,603		—		16,603		—		1,503		—		1,503
Total financial assets	$	45,743	$	111,112	$	—	$	156,855	$	106,782	$	8,005	$	—	$	114,787

Cash equivalents and investments, all of which are classified as available-for-sale securities and restricted cash, consisted of the following (in thousands):

	March 31, 2020									December 31, 2019										March 31, 2021								December 31, 2020
	Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value		Cost			Unrealized Gain		Unrealized (Loss)			Estimated Fair Value		Cost		Unrealized Gain		Unrealized (Loss)		Estimated Fair Value		Cost			Unrealized Gain		Unrealized (Loss)		Estimated Fair Value
Money market funds	$	26,059	$	—	$	—		$	26,059		$	45,743	$	—	$	—		$	45,743	$	100,579	$	—	$	—	$	100,579		$	106,782	$	—	$	—	$	106,782
Corporate notes and commercial paper		74,525		22		(52	)		74,495			55,761		13		(4	)		55,770		—		—		—		—			6,501		1		—		6,502
U.S. treasury securities		28,428		99		—			28,527			38,710		29		—			38,739
U.S. government agency securities		9,004		6		—			9,010			16,599		4		—			16,603		1,500		—		—		1,500			1,501		2		—		1,503
	$	138,016	$	127	$	(52	)	$	138,091		$	156,813	$	46	$	(4	)	$	156,855	$	102,079	$	—	$	—	$	102,079		$	114,784	$	3	$	—	$	114,787
Classified as:
Cash equivalents								$	40,008									$	59,491							$	100,309								$	106,342
Short-term investments									94,637										96,924								1,500									8,005
Long-term investments									3,006										—
Restricted cash									440										440								270									440
Total cash equivalents, restricted cash and investments								$	138,091									$	156,855							$	102,079								$	114,787

At March 31, ~~2020,~~2021, the remaining contractual maturities of available-for-sale securities were less than ~~18 months.~~one year. There have been no0 significant realized gains or losses on available-for-sale securities for the periods presented. As of March 31, 2021 and December 31, 2020, there were 0 unrealized losses on cash equivalents and ~~investments were $52,000 and the losses were deemed to be temporary.~~ ~~The gross unrealized loss that had been in a continuous loss position for 12 months or longer was $0 as of March 31, 2020, and December 31, 2019.~~ The Company does not intend to sell its securities that are in an unrealized loss position, and it is unlikely that the Company will be required to sell its securities before recovery of their amortized cost basis, which may be maturity. Factors considered in determining whether a loss is temporary include the length of time and extent to which the fair value has been less than the amortized cost basis and whether the Company intends to sell the security or whether it is more likely than not that the Company would be required to sell the security before recovery of the amortized cost basis. investments. As of March 31, ~~2020,~~2021, the Company had a total of ~~$138.5~~$103.1 million in cash, cash equivalents, restricted cash and investments, which includes ~~$0.5~~$1.0 million in cash and ~~$138~~$102.1 million in cash equivalents, restricted cash and investments.

	March 31, 2020		December 31, 2019		March 31, 2021		December 31, 2020
Accrued clinical and manufacturing expenses	$	8,337	$	8,270	$	7,704	$	7,910
Accrued payroll and related expenses		2,578		5,045		2,535		5,142
Collaboration reimbursement advances		1,278		1,547
Current portion of lease liability		1,533		1,478		1,039		1,903
Other		1,288		1,232		878		1,452
Total accrued and other liabilities	$	15,014	$	17,572	$	12,156	$	16,407

The Company has a non-cancelable facility lease agreement, or the Lease, for office and laboratory facilities in South San Francisco, California, with a remaining lease term of ~~3.84~~2.8 years, through January 2024, and a two-year renewal option prior to expiration. The renewal option to extend the Lease was not considered in the determination of the right-of-use asset or the lease liability for the Lease as the Company did not consider it reasonably certain that it would exercise any such option. The Lease provides that the Company is obligated to pay certain variable costs, including taxes and operating expenses. The Lease is classified as an operating lease. In addition, the Company had a non-cancelable sublease agreement for a portion of its facilities through February 2020. The sublease agreement provided that the subtenant was obligated to pay its share of the variable costs under the Lease. ~~The~~Through March 7, 2021 the Company ~~has~~ measured the present value of its lease liability using an estimated incremental borrowing rate of 9%.

13On March 8, 2021, the Company amended its lease to reduce its rentable area from approximately 54,000 square feet to approximately 34,000 square feet. The related reduction in rent was effective January 1, 2021. In connection with the amendment, the Company also reduced its existing letter of credit from $440,000 to $270,000 as a security deposit to the lease. Subsequent to the amendment, which was determined to be a modification of the lease, the Company remeasured the present value of its lease liability using an estimated incremental borrowing rate of 7.5%. The Company recognized a gain of $0.4 million, included in interest and other income, net in its unaudited condensed consolidated statement of operations for the three months ended March 31, 2021, which represents the difference between the reduced lease liability and the reduction in the operating lease right of use asset.

The components of net operating lease costs included in the condensed consolidated statement of operations were as follows (in thousands):

	Three Months Ended March 31,						Three Months Ended March 31,
Operating Lease Costs:	2020			2019			2021		2020
Straight-line rent expense related to facility operating lease	$	544		$	544		$	484	$	544
Variable rent expense related to operating lease		378			347			244		378
Sublease income		(187	)		(275	)		—		(187	)
Variable sublease income		(93	)		(133	)		—		(93	)
Net operating lease costs	$	642		$	483		$	728	$	642

Cash paid for amounts included in the measurement of the lease liabilities for the three months ended March 31, 2021 and 2020, was $0.6 million and $0.6 million, respectively, and was included in net cash used in operating activities in the Company’s unaudited condensed consolidated statements of cash flows.

The balance sheet classification of the Company’s operating lease liability was as follows (in thousands):

	March 31, 2020		December 31, 2019		March 31, 2021		December 31, 2020
Operating Lease Liability:
Current portion included in accrued and other liabilities	$	1,533	$	1,478	$	1,039	$	1,903
Noncurrent operating lease liability		6,260		6,718		2,707		4,815
Total operating lease liability	$	7,793	$	8,196	$	3,746	$	6,718

The maturities of the Company’s lease liability as of March 31, ~~2020,~~2021, was as follows (in thousands):

Year ending December 31:
2020 (excluding the three months ended March 31, 2020)		1,563
2021		2,413
2021 (excluding the three months ended March 31, 2021)				$	901
2022		2,485			1,546
2023		2,560			1,592
2024		219			136
Total lease payments		9,240			4,175
Less: interest		(1,447	)		(429	)
Present value of lease liability	$	7,793		$	3,746

In December 2019, the Company entered into a sales agreement with Jefferies LLC, or Jefferies, as sales agent and underwriter, pursuant to which the Company could issue and sell shares of its common stock with an aggregate maximum offering price of $50.0 million under an at-the-market offering program, or the 2019 ATM program. The Company will pay Jefferies up to 3% of gross proceeds for any common stock sold through the sales agreement. During the three months ended March 31, 2020, the Company sold an aggregate of 1,160,425 shares at an average price of approximately $6.51 per share for gross proceeds of $7.6 million, resulting in net proceeds of $7.4 million after underwriting fees and offering expenses. As of March 31, 2020, the Company had sold all available shares under the 2019 ATM program.

~~In March~~August 2020, the Company entered into a sales agreement with Jefferies as sales agent and underwriter, pursuant to which the Company could issue and sell shares of its common stock with an aggregate maximum offering price of ~~$50.0~~$75.0 million under an at-the-market offering program, or the ~~2020~~ ATM program. The Company will pay Jefferies up to 3% of gross proceeds for any common stock sold through the sales agreement. During the three months ended March 31, 2021, the Company sold 3,197,166 shares under the ATM program at an average price per share of $3.04, for net proceeds of $9.5 million. As of March 31, ~~2020, no~~2021, a total of 3,197,166 shares had been sold under the ~~2020~~ ATM program.

A summary of stock option activity was as follows (in thousands, except weighted-average exercise price and contractual term amounts):

	Options Outstanding									Options Outstanding
	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Value Intrinsic		Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Value Intrinsic
Outstanding — December 31, 2019		6,513		$	6.89
Outstanding — December 31, 2020											8,637		$	6.91
Options granted		2,123		$	7.41						1,781		$	2.98
Options exercised		(13	)	$	4.18						(1	)	$	2.31
Options cancelled		(100	)	$	8.35						(981	)	$	6.21
Outstanding — March 31, 2020		8,523		$	7.01		7.66	$	1,533
Exercisable — March 31, 2020		4,160		$	7.43		6.14	$	1,290
Outstanding — March 31, 2021											9,436		$	6.24		7.08	$	39
Exercisable — March 31, 2021											5,339		$	7.24		5.64	$	39

During the three months ended March 31, 2021, the Company issued 515,523 restricted stock units, or RSUs, to its employees. The RSUs vest 25% annually over 4 years commencing on the date of grant. The RSUs are measured at grant date fair value, at the market price of the Company’s common stock on the grant date. The Company records stock-based compensation expense related to the RSUs ratably over the employee respective requisite service period.

On January 20, 2021, the Company granted 1,607,812 performance-based restricted stock units, or PSUs, to employees. The PSUs vest 20% on January 3, 2022 and 80% upon the achievement of two goals that are expected to be achieved by January 3, 2022. The PSUs were measured at grant date fair value, using the market price of the Company’s common stock on the grant date of $2.98. The Company estimates that all vesting conditions are probable of being achieved and has elected to recognize compensation expense for the PSUs as one aggregate award using the straight-line method over the estimated implicit service period from the grant date to January 3, 2022. The Company will monitor the probability of achievement of the goals each reporting period and adjust its estimates accordingly. During the three months ended March 31, 2021, the Company recorded $0.9 million of expense related to the PSUs.

A summary of restricted stock unit activity was as follows (in thousands, except weighted-average grant-date fair value and contractual term amounts):

Total stock-based compensation expense related to the Company’s 2010 Equity Incentive Plan, 2014 Equity Incentive Plan, 2018 ~~Incentive~~Inducement Plan, and the 2014 Employee Stock Purchase Plan was as follows (in thousands):

	Three Months Ended March 31,				Three Months Ended March 31,
	2020		2019		2021		2020
Research and development	$	1,075	$	779	$	1,280	$	1,075
General and administrative		918		904		1,415		918
Total stock-based compensation	$	1,993	$	1,683	$	2,695	$	1,993

Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive.

Potentially dilutive securities that were not included in the diluted net loss per share calculations because they would be anti-dilutive were as follows (in thousands):

	March 31,				March 31,
	2020		2019		2021		2020
Options to purchase common stock		8,523		6,489		9,436		8,523
Employee stock plan purchases		80		68		42		80
Restricted stock units subject to future vesting						2,048		—
Total		8,603		6,557		11,526		8,603

On January 27, 2017, the Company entered into a collaboration and license agreement with Incyte, or the Incyte Collaboration Agreement. Under the terms of the Incyte Collaboration Agreement, the Company granted Incyte an exclusive, worldwide license to develop and commercialize its small molecule arginase inhibitors for hematology and oncology indications. ~~The~~Through September 30, 2020, the parties ~~are collaborating~~collaborated on and ~~co-funding~~co-funded the development of the licensed products, with Incyte bearing 70% and the Company bearing 30% of global development costs. The parties ~~will~~would share profits and losses in the United States, with 60% to Incyte and 40% to the Company. The Company ~~will~~would have the right to co-detail the licensed products in the United States, and Incyte ~~will~~would pay the Company tiered royalties ranging from the low to mid-double digits on net sales of licensed products outside the United States.

The Incyte Collaboration Agreement also provides that the Company may choose to opt out of its co-funding ~~obligation, in which case~~obligations at any time. On August 28, 2020, the ~~United States~~Company delivered written notice to Incyte of its decision to opt out of its co-development rights effective September 30, 2020. As a result of the Company’s decision to opt out, Incyte will pay all costs to develop INCB001158 or any other licensed products. In addition, the Company’s rights to U.S. profit sharing will no longer be in effect, and instead Incyte will pay ~~the Company~~Calithera tiered royalties ranging from the low double digits to ~~mid-double digits~~mid-teens on net sales of licensed products ~~both~~in the U.S., an incremental 3% royalty on annual net sales in the United States ~~and outside~~of such licensed product until such incremental royalty equals 120% of previous development expenditures incurred by the ~~United States, and additional royalties to reimburse the Company for previously incurred development costs.~~Company.

Under the Incyte Collaboration Agreement, the Company received an upfront payment of $45.0 million in February 2017. In March 2017, the Company achieved a development milestone of $12.0 million, for which the Company received payment in May of 2017. The Company is also eligible to receive up to an additional $418.0 million in potential development, regulatory and sales milestones. In April 2020, the Company filed a complaint against Incyte in the Superior Court of California, San Francisco County, asserting claims for breach of contract arising out of Incyte’s failure to pay two milestone payments the Company believes are due

under the Collaboration Agreement. As of March 31, ~~2020, no~~2021, 0 revenue has been recognized for these two milestones as the collectability remains uncertain.

~~The Incyte Collaboration Agreement also provides that the Company may choose to opt out of its co-funding obligations at any time. In this scenario, the~~Total remaining potential development, regulatory and commercialization milestones ~~from Incyte will be up to an additional $738.0~~as of March 31, 2021 were $ 738.0 million. The Company would no longer be eligible to receive future United States profits and losses but would be eligible to receive tiered royalty payments on future global sales, including United States sales. In addition, if the Company opts out, the Company will receive an incremental 3% royalty on annual net sales in the United States of such licensed product until such incremental royalty equals 120% of previous development expenditures incurred by the Company.

The Incyte Collaboration Agreement is considered to be under the scope of ~~FASB~~ASC Topic 808, Collaborative Arrangements. The Company has concluded that the research and development co-funding activities were not representative of a customer relationship and this unit of account is accounted for as an increase to or reduction of research and development expenses, rather than as revenue. In addition, the Company has analogized to ASC 606 for other aspects of the arrangement. The performance obligations under the Incyte Collaboration Agreement consist of intellectual property licenses and the performance of certain manufacturing and manufacturing technology transfer services. The Company determined that the license is not distinct from the associated manufacturing and technology transfer services to be performed under the agreement. Specifically, the Company believes the license is not capable of being distinct, as Incyte did not have the know-how to manufacture the collaboration product without Calithera’s

assistance until completion of the manufacturing technology transfer process, and no other third parties could perform such assistance due to the early stage nature of the licensed intellectual property as well as Calithera’s propriety knowledge with respect to the licensed intellectual property.

In accordance with ASC 606, the Company determined the transaction price to be $57.0 million, representing the $45.0 million upfront payment and the $12.0 million developmental milestone payment from Incyte that was earned in March 2017. The $57.0 million transaction price was recognized over the estimated performance period, based on the measure of progress toward completion for the combined performance obligation, which was satisfied as of June 2018. The measure of progress towards completion was based on the effort of certain employees within the Company who dedicated time to complete the manufacturing services and technology transfer to Incyte. NoNaN subsequent revenue has been recognized related to the Incyte Collaboration Agreement through March 31, ~~2020.~~2021.

Net costs associated with co-development activities performed under the agreement are included in research and development expenses in the accompanying unaudited condensed consolidated statements of operations, with any reimbursement of costs by Incyte reflected as a reduction of such expenses. For the three months ended March 31, ~~2020~~2021 and ~~2019,~~2020, net costs reimbursable from (to) ~~from~~ Incyte were ~~($0.1)~~$0.7 million and ~~$0.8~~($0.1) million, respectively. As of March 31, ~~2020,~~2021, the receivable due from Incyte was $1.0 million.

In October 2018, the Company entered into a clinical trial collaboration and supply agreement with Pfizer to evaluate Pfizer’s PARP inhibitor talazoparib (Talzenna) and CDK4/6 inhibitor palbociclib (Ibrance), each in combination with telaglenastat. Under the terms of the clinical collaboration, Pfizer provides reimbursement of certain development costs. Costs associated with development activities performed under the clinical collaboration are included in research and development expenses in the accompanying consolidated statements of operations, with any reimbursements of costs reflected as a reduction of such expenses. For the three months ended March 31, ~~2020~~2021 and ~~2019,~~2020, net costs reimbursed and reimbursable by Pfizer were not material to the condensed consolidated financial statements.

In December 2014, the Company entered into an exclusive license agreement with Mars, Inc., by and through its Mars Symbioscience division, or Symbioscience, under which the Company has been granted the exclusive, worldwide license to develop and commercialize Symbioscience’s portfolio of arginase inhibitors for use in human healthcare, or the Symbioscience License Agreement. There were no0 expenses related to its licensing arrangement with Mars Symbioscience recorded in the three months ended March 31, ~~2020~~2021 and ~~2019.~~2020.

The Company may make future payments of up to $23.6 million contingent upon attainment of various development and regulatory milestones and $95.0 million contingent upon attainment of various sales milestones. Additionally, the Company will pay royalties on sales of the licensed product, if such product sales are ever achieved. If the Company develops additional licensed products, after achieving regulatory approval of the first licensed product, the Company would owe additional regulatory milestone payments and additional royalty payments based on sales of such additional licensed products.

In ~~April~~October 2020, the Company ~~entered into an underwriting agreement with Citigroup Global Markets, Inc.,~~was awarded $2.4 million from the Cystic Fibrosis Foundation, or CFF, to support the ~~Underwriter, pursuant~~clinical development of CB-280 in cystic fibrosis. The award will be paid in installments upon the achievement of certain milestones. The Company recognizes the CFF milestones awards as a reduction to ~~which~~research and development expenses in the accompanying unaudited consolidated statements of operations in the period the milestone is achieved and expenses have been incurred. For the three months ended March 31, 2021, 0 amounts from the CFF were recognized as a reduction of research and development expenses.

The award contains provisions where the Company ~~issued and sold 5,750,000 shares of common stock, including 750,000 shares sold pursuant~~must repay up to two times the award if it ceases to use commercially reasonable efforts to develop CB-280. Upon commercialization, the Company will owe certain royalty payments to the ~~Underwriter’s exercise in full of their option~~CFF up to ~~purchase additional shares.~~a royalty cap. The ~~price~~Company may also be obligated to make a payment to CFF if the ~~public~~Company transfers, sells or licenses a product in the ~~offering was $6.25 per share, and the Underwriter purchased the shares from~~cystic fibrosis field, or if the Company atenters into a ~~price~~change of ~~$5.875 per share. The net proceeds to~~control transaction.

On January 4, 2021, the Company ~~from this public offering were~~announced a plan to reduce its workforce by approximately ~~$33.5~~35% to extend its cash runway and ensure long-term sustainability. The Company anticipates the one-time severance-related charge associated with the workforce reduction to be approximately $1.2 million, ~~after deducting underwriting discounts~~which will be substantially completed by the third quarter of 2021. During the three-month period ended March 31, 2021, the Company recognized $0.9 million and ~~commissions~~$0.2 million of severance-related charges to research and ~~other offering expenses.~~

development and general and administrative expenses, respectively, which is included in operating expenses in the unaudited condensed consolidated statements of operations.

A summary of activity in the accrued liability associated with the Company’s reduction in workforce for the three months ended March 31, 2021 was as follows (in thousands):

Item 2. MANAGEMENT’S ~~DISCUSSION~~DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our unaudited condensed consolidated financial statements and related notes included in Part I, Item 1 of this report.

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Forward-looking statements are identified by words such as “believe,” “will,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “expect,” “predict,” “could,” “potentially” or the negative of these terms or similar expressions. You should read these statements carefully because they discuss future expectations, contain projections of future results of operations or financial condition, or state other “forward-looking” information. These statements relate to our future plans, objectives, expectations, intentions and financial performance and the assumptions that underlie these statements. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those anticipated in the forward-looking statements. Factors that might cause such a difference include, but are not limited to, those discussed in this report in Part II, Item 1A — “Risk Factors,” and elsewhere in this report. Forward-looking statements are based on our management’s beliefs and assumptions and on information currently available to our management. These statements, like all statements in this report, speak only as of their date, and we undertake no obligation to update or revise these statements in light of future developments. We caution investors that our business and financial performance are subject to substantial risks and uncertainties. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based on information available to us as of the date of this Quarterly Report on Form 10-Q. While we believe that information provides a reasonable basis for these statements, that information may be limited or incomplete. Our statements should not be read to indicate that we have conducted an exhaustive inquiry into or review of, all relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely on these statements.

We are a clinical-stage bio-pharmaceutical company focused on fighting cancer and other life-threatening diseases by discovering and developing novel small molecule drugs that target cellular metabolism. Tumor metabolism and immuno-oncology have emerged as promising new fields for cancer drug discovery, and recent clinical successes with therapeutic agents in each field have created fundamentally new potential therapies for cancer patients. With our unique approach, we have established a broad pipeline of small molecule drug candidates that target enzymes controlling metabolically critical pathways in tumor cells and immune cells. We have multiple internally discovered clinical stage compounds that are all enzyme inhibitors. While we are primarily focused on oncology, we ~~may~~are opportunistically ~~develop~~developing therapeutics outside of oncology where we can leverage our existing expertise in immune cell metabolism to treat diseases with unmet need.

Through genetic mutations that alter fundamental metabolic pathways, cancer cells can acquire the ability to grow in an uncontrolled manner, but they also acquire nutrient dependencies that can differentiate them from normal cells. Targeting these nutrient dependencies by inhibiting specific metabolic pathways in cancer cells is a novel therapeutic approach to blocking the uncontrolled growth of tumors. Our lead product candidate, telaglenastat ~~(CB-839),~~or CB-839, takes advantage of the critical dependency many cancers have on the nutrient glutamine for growth and survival. We believe telaglenastat has the potential to be an important new therapeutic agent with a novel mechanism of action for the treatment of a broad range of cancers, and is the first selective allosteric glutaminase inhibitor to enter clinical trials. We retain all commercial rights to telaglenastat and have been granted a U.S. patent, which includes composition of matter coverage for telaglenastat through ~~2032.~~2037, as well as patents applied for/issued in other territories.

We are currently developing telaglenastat in combination with standard therapies in a select set of solid tumors. Our lead development pathway for telaglenastat is for the treatment of KEAP1 or NRF2 mutated non-small cell lung cancer, or NSCLC. According to third-party market research, U.S. incidence of NSCLC is approximately 200,000 with 20-25% of these patients harboring KEAP1 or NRF2 activating mutations. Recently presented clinical data evaluating front-line standard-of-care chemoimmunotherapy treatment for NSCLC patients with mutations in KEAP1/NRF2 demonstrated inferior clinical outcomes compared to patients without these mutations. Thus, NSCLC patients with KEAP1 or NRF2 mutations are a population with an unmet clinical need. Pre-clinical studies have shown that activation of the KEAP1/NRF2 pathway in lung tumors makes them dependent on glutaminase activity for growth and survival, and treatment with telaglenastat selectively blocks their growth. In September 2020, we treated the first patient in the KEAPSAKE study, which is a randomized Phase 2 clinical trial of the glutaminase inhibitor telaglenastat in combination with standard-of-care therapy. The KEAPSAKE study will evaluate the safety and anti-tumor activity of telaglenastat plus standard-of-care chemoimmunotherapy as front-line treatment for patients with stage IV non-squamous non-small cell lung cancer whose tumors have a KEAP1 or NRF2 mutation determined by next-generation sequencing. The double-blind telaglenastat trial will enroll approximately 120 patients with stage IV non-squamous NSCLC with the KEAP1 or NRF2 mutation. Patients will be randomized to receive telaglenastat or placebo, in combination with pembrolizumab, carboplatin and pemetrexed. The study will evaluate the safety and investigator assessed progression-free survival, or PFS, of telaglenastat plus this standard of care chemoimmunotherapy regimen. We anticipate sharing interim data from the KEAPSAKE trial in the fourth quarter of 2021.

We were previously developing telaglenastat for the treatment of renal cell carcinoma, or ~~RCC, where~~RCC. In January 2021, we ~~are evaluating telaglenastat in~~announced the results of the CANTATA trial, ~~(NCT03428217),~~ a 444 patient global, randomized, double-blind trial designed to evaluate the safety and efficacy of telaglenastat in combination with cabozantinib versus placebo with cabozantinib in patients with advanced clear cell RCC ~~patients~~ who ~~have been treated with one~~had progressed on immune checkpoint inhibitors or ~~two prior lines of systemic therapy.~~ anti-angiogenic therapies. The trial did not meet the primary endpoint isof progression-free survival, or ~~PFS,~~PFS. Based on this result, we evaluated our operational and workforce needs to extend our cash runway and ensure long-term sustainability. We reduced our workforce by blinded independent review, and a key secondary endpoint is overall survival. The trial is designed with registrational intent. Because of the recent progress in developing new therapies for the treatment of RCC patients today, the RCC market, accordingapproximately 35% to ~~third-party market research, is expected~~preserve cash resources. We currently have no plans to ~~grow significantly, from over $4 billion in 2020 to $7 billion in 2026. The U.S. Food and Drug Administration, or FDA, has granted Fast Track designation to~~further develop telaglenastat in combination with cabozantinib, for the treatment of patients with metastatic RCC who have received one or two prior lines of therapy. The CANTATA trial was fully enrolled in October 2019 and we advised at that time that we planned to report top-line efficacy and safety data from the trial in the second half of 2020, and more recently guided towards late third quarter or fourth quarter of 2020. In light of delays associated with COVID-19, we now expect top-line data in the fourth quarter of 2020. We have made accommodations to facilitate study conduct during the pandemic, including allowing patients to have scans performed at local clinical centers to facilitate compliance with the study schedule of assessments, and to receive a larger allocation of study drug in order to reduce the number of visits required to the clinical site, if necessary. While affirming that the

~~readout is expected by the end of 2020, the updated guidance allows for additional time for activities that require visits to clinical sites, including data monitoring.~~

In June 2019, we reported the results of the randomized, double blind, placebo-controlled ENTRATA study of telaglenastat, which met its primary endpoint. ENTRATA provides the first clinical proof of concept for telaglenastat in a randomized trial.

We also plan to develop telaglenastat for the treatment of NRF2/KEAP1 mutated non-small cell lung cancer (NSCLC). The NRF2/KEAP1 pathway is known to drive the development of certain cancers, including a significant proportion of NSCLC, through the regulation of reactive oxygen species (ROS) in a manner that makes cells highly dependent on glutaminase activity. The randomized Phase 2 trial of telaglenastat for the treatment of lung cancer continues to progress towards multiple site openings. We will be evaluating the combination of telaglenastat plus pembrolizumab and standard chemotherapy versus placebo with pembrolizumab and standard chemotherapy. However, given the challenges associated with opening new clinical studies during the current stage of the COVID-19 pandemic, we expect to delay enrollment of the first patient until the third quarter of 2020, pending further developments in the COVID-19 situation.RCC. We plan to present ~~interim data~~an analysis from ~~this~~the CANTATA trial at the American Society of Clinical Oncology Annual Meeting in June 2021.

~~In connection with~~As part of our Pfizer clinical collaboration, we ~~have begun trials~~initiated a trial with the CDK 4/6 inhibitor ~~IBRANCE®, and the dual-mechanism poly (ADP-ribose) polymerase (PARP) inhibitor TALZENNA®, each~~palbociclib, in combination with ~~telaglenastat. In March 2019, we initiated a~~telaglenastat in July 2019. The Phase 1/2 trial (NCT03965845) of the combination of telaglenastat plus ~~Talzenna in patients with renal cell carcinoma and triple negative breast cancer. In July 2019, we initiated a Phase 1/2 trial of the combination of telaglenastat plus Ibrance~~palbociclib is ongoing in patients with KRAS mutated colorectal cancer and KRAS mutated non-small cell lung cancer. ~~Dose escalation has been completed for both trials. Dose expansion cohorts have been temporarily paused due to~~Encouraging efficacy and safety of the ~~COVID-19 situation. We expect enrollment to resume~~combination was observed in PDAC patients treated in the ~~second quarter~~dose escalation phase of ~~2020.~~the trial. In November 2020, we announced the expansion of the study to include an additional cohort of patients with pancreatic ductal adenocarcinoma whose tumors harbor mutations in both KRAS and CDKN2A. Approximately 50% of PDAC patients harbor mutations in both KRAS and CDKN2A.

Our product candidate, ~~INCB001158~~CB-280, is an oral inhibitor of arginase, an enzyme that depletes the amino acid arginine. It is being developed for the treatment of cystic fibrosis, or CF. According to third-party market research, there are over 70,000 people living with CF, over 30,000 of those are in the US. By 2026, worldwide sales for CF drugs are expected to surpass $11 billion. Arginase depletes arginine, which is critical for the generation of NO, or nitric oxide. NO has critical anti-microbial effects in lung and also mediates bronchodilation. CB-280 is a ~~key metabolic nutrient~~novel oral arginase inhibitor which is solely owned by Calithera. We completed a Phase 1 Single Ascending Dose trial to evaluate the safety, tolerability and pharmacokinetic profile of oral CB-280 in healthy volunteers. In July 2020, we initiated a Phase 1b clinical trial in adult patients with cystic fibrosis that are on a stable regimen of CF therapies and have chronic airway infection. The randomized, double blind, placebo-controlled, dose escalation trial will evaluate multiple ascending doses of CB-280, dosed orally twice daily for ~~T-cells.~~14 days, compared to placebo in up to 32 adult CF patients to determine a safe dose range for CB-280. Enrollment in this study is ongoing and we expect to share interim data in the second half of 2021. In October 2020, we were awarded up to $2.4 million from the Cystic Fibrosis Foundation to support development of CB-280.

An additional arginase inhibitor, INCB001158, was discovered by Calithera and is being ~~co-developed with~~developed by Incyte Corporation, or Incyte, for oncology and hematology indications, and is currently being evaluated in Phase 1/2 trials as a monotherapy and in combination with other anti-cancer agents. ~~Arginase depletes arginine,~~In January 2017, we entered into a ~~nutrient that is critical for~~collaboration and license agreement, or the ~~activation and proliferation~~Incyte Collaboration Agreement, with Incyte. Under the terms of the ~~body’s cancer-fighting immune cells, such as cytotoxic T-cells~~Incyte Collaboration Agreement, we granted Incyte an exclusive, worldwide license to co-develop and natural killer (NK)-cells. In some physiological circumstances such as maternal-fetal immune tolerance, arginase-mediated depletion of arginine plays an important role in suppressing the immune system. But in many tumors, arginase-expressing myeloid cells accumulateco-commercialize our small molecule arginase inhibitors for hematology and maintain an immunosuppressive environment, blocking the ability of T-cells and NK-cells to kill cancer cells. We have demonstrated that arginase-expressing myeloid cells can accumulate in a number of cancers, including lung, gastrointestinal, bladder, renal, squamous cell head and neck and acute myeloid leukemia. We believe that inhibitors of arginase can promote an anti-tumor immune response by restoring arginine levels, thereby allowing activation of the body’s own immune cells, including cytotoxic T-cells and NK-cells.oncology indications. In April 2020, we filed a complaint against Incyte in the Superior Court of California, San Francisco County, asserting claims for breach of contract arising out of Incyte’s failure to pay two milestone payments we believe are due under the Incyte Collaboration ~~and License Agreement between us and Incyte, or~~Agreement. Effective September 30, 2020 we opted out of our co-development obligations as permitted under the terms of the Incyte Collaboration Agreement. ~~Clinical trials being conducted~~As a result of our decision to opt out, Incyte will pay all costs to develop INCB001158 or any other licensed products. Incyte will pay us tiered royalties ranging from the low double digits to mid-teens on net sales of licensed products and total remaining potential development, regulatory and commercialization milestones of $738.0 million.

Our research focus has remained on metabolic enzymes. We have two earlier stage immunotherapy programs which include our candidate CB-708, which targets CD73, and our candidate CB-668 which targets IL4I1; both of these enzymes are secreted by ~~us and Incyte evaluating INCB001158 are ongoing as planned.~~

~~Arginase inhibitors also have potential~~immune cells in the treatment of cystic fibrosis; accordingly, we have selected CB-280, a unique oral arginase inhibitor, for the treatment of cystic fibrosis, or CF, patients. It is a novel oral arginase inhibitor which is solely owned by Calithera. tumor microenvironment.

We have completed a Phase 1 Single Ascending Dose trial to evaluate the safety, tolerability and pharmacokinetic profile of oral CB-280 in healthy volunteers and a Phase 1b clinical study in people with cystic fibrosis is planned. Site openings are in progress. However, given the challenges associated with opening new clinical studies during the current stage of the COVID-19 pandemic, we expect to delay enrollment in the first patient until the third quarter of 2020, pending further developments in the COVID-19 situation.

We are a fully integrated biopharmaceutical company with expertise in biology and chemistry, and our ongoing research efforts are focused on discovering additional product candidates for the treatment of cancer and other life-threatening diseases. We have discovered and developed ~~the clinical candidate~~ CB-708, a highly potent, selective, ~~orally administered~~orally-bioavailable small molecule inhibitor of CD73. Preclinical data were presented at the 2019 American Association for Cancer Research annual meeting and the 2019 Society for Immunotherapy of Cancer meeting demonstrating that ~~inhibits CD73,~~CB-708 has immune-mediated, single agent activity in syngeneic mouse tumor models. In pre-clinical studies CB-708 was well-tolerated and shows enhanced anti-tumor activity when combined with either an ~~enzyme that converts adenosine monophosphate to generate the immunosuppressive agent adenosine.~~ anti-PD-L1 immunotherapy or with chemotherapeutic agents, such as oxaliplatin or doxorubicin.

We have also ~~developed~~identified CB-668, an investigational first-in-class, potent, orally administered IL4I1 inhibitor as a novel immuno-oncology approach to cancer. CB-668 is an inhibitor of the enzyme IL4I1, an enzyme that is expressed by tumor cells and antigen presenting cells, metabolizes phenylalanine, tyrosine and tryptophan to produce hydrogen peroxide, an inhibitor of T-cell function. In particular, IL4I1 can metabolize tryptophan to kynurenic acid and other metabolites that lead to immunosuppression in the tumor microenvironment. Preclinical data were presented at the 2020 Society for Immunotherapy of Cancer Annual Meeting. In syngeneic mouse models CB-668 exhibited immune mediated, single agent activity and augmented activity in combination with checkpoint inhibitors. IL4I1 expression has been correlated with poor clinical outcomes and expression is elevated in multiple tumor types including ovarian and B-cell tumors. We plan to continue preclinical studies on CB-668.

There have been no significant changes in our critical accounting policies and estimates disclosed in our Annual Report on Form 10-K for the year ended December 31, ~~2019,~~2020, as filed with the SEC.

Research and development expenses represent costs incurred to conduct research, such as the discovery and development of our product candidates. We recognize all research and development costs as they are incurred. Costs associated with co-development activities performed under our collaboration agreements with Incyte and Pfizer and activity performed under our award with the Cystic Fibrosis Foundation are included in research and development expenses, with any reimbursement of costs reflected as a reduction of such expenses.

The largest component of our total operating expenses has historically been our investment in research and development activities including the clinical development of our product candidates. We allocate to research and development expenses the salaries, benefits, stock-based compensation expense, and indirect costs of our clinical and preclinical programs on a program-specific basis, and we include these costs in the program-specific expenses.

The following table shows our research and development expenses for the three months ended March 31, ~~2020~~2021 and ~~2019:~~2020:

	Three Months Ended March 31,				Three Months Ended March 31,
	2020		2019		2021		2020
	(in thousands)				(in thousands)
Development:
Development candidate:
Telaglenastat (CB-839)	$	15,031	$	13,603	$	11,705	$	15,031
INCB001158		1,556		2,750		—		1,556
CB-280		1,491		1,000		1,779		1,491
Total development		18,078		17,353		13,484		18,078
Preclinical and research:
Preclinical and research		2,047		2,886		1,855		2,047
Total Research and Development	$	20,125	$	20,239
Total					$	15,339	$	20,125

We expect our research and development expenses will ~~increase during~~decrease over the next ~~few years as we advance our product candidates into and through clinical trials, and pursue regulatory approval~~year primarily due to the completion of our ~~product candidates,~~CANTATA trial and ~~as we begin~~ our ~~efforts~~workforce reduction announced in ~~the potential commercial launch of telaglenastat for RCC, which will also require a significant investment in contract manufacturing and inventory build-up related costs.~~January 2021.

The process of conducting clinical trials necessary to obtain regulatory approval is costly and time consuming. We may never succeed in achieving marketing approval for our product candidates. The probability of success of our product candidates may be affected by numerous factors, including clinical data, competition, manufacturing capability and commercial viability. As a result, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of any of our product candidates.

General and administrative expenses consist of personnel costs, allocated expenses and other expenses for outside professional services, including legal, audit and accounting ~~services.~~services, insurance, investor relations and other expenses associated with being a public company. Personnel costs consist of salaries, benefits and stock-based compensation. Allocated expenses consist of facilities and other

allocated expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation expense and other supplies. We ~~have incurred~~expect our general and ~~expect to continue to incur additional~~administrative expenses ~~as a result of operating as a public company, including costs to comply with~~will decrease over the rules and regulations applicable to companies listed on a national securities exchange and costs related to compliance and reporting obligations pursuant to the rules and regulations of the SEC. In April 2020, we filed a complaint against Incyte in the Superior Court of California, San Francisco County,

asserting claims for breach of contract arising out of Incyte’s failure to pay two milestone payments we believe are due under the Incyte Collaboration Agreement. We expect to incur higher legal expenses as this matter proceeds.next year.

	Three Months												Three Months
	Ended March 31,						Change						Ended March 31,						Change
	2020			2019			$			%			2021			2020			$			%
	(in thousands, except percentages)
Operating expenses:
Research and development	$	20,125		$	20,239		$	(114	)		-1	%	$	15,339		$	20,125		$	(4,786	)		-24	%
General and administrative		4,946			4,164			782			19	%		5,428			4,946			482			10	%
Total operating expenses		25,071			24,403			668			3	%		20,767			25,071			(4,304	)		-17	%
Loss from operations		(25,071	)		(24,403	)		(668	)		3	%		(20,767	)		(25,071	)		4,304			-17	%
Interest and other income, net		625			716			(91	)		-13	%		372			625			(253	)		-40	%
Net loss	$	(24,446	)	$	(23,687	)	$	(759	)		3	%	$	(20,395	)	$	(24,446	)	$	4,051			-17	%

Research and Development. Research and development expenses decreased ~~$0.1~~$4.8 million, or 1%24%, from ~~$20.2 million for the three months ended March 31, 2019 to~~ $20.1 million for the three months ended March 31, ~~2020.~~2020 to $15.3 million for the three months ended March 31, 2021. The decrease of ~~$0.1~~$4.8 million was due to a ~~$1.2~~$3.3 million decrease in expenses associated with the telaglenastat program, a $1.6 million decrease in the INCB001158 program and a ~~decrease of $0.8~~$0.2 million ~~for investment~~decrease in our early stage research programs, partially offset by ~~a $1.4 million increase in the telaglenastat program, including for our CANTATA trial where we completed enrollment in 2019 and expect top-line results in late fourth quarter of 2020 and~~ an increase of ~~$0.5~~$0.3 million in the CB-280 program.

General and Administrative.General and administrative expenses increased ~~$0.7~~$0.5 million, or ~~19%~~10%, from ~~$4.2 million for the three months ended March 31, 2019, to~~ $4.9 million for the three months ended March 31, 2020, ~~primarily related~~ to ~~$0.5 million higher professional services costs mainly for legal and consulting services, and $0.2 million in higher facility costs related to the expiration of our sublease in February 2020.~~

~~Interest and Other Income, net.~~ ~~Interest and other income, net decreased $0.1 million, or 13%, from $0.7~~$5.4 million for the three months ended March 31, ~~2019~~2021. The increase was primarily related to an $0.9 million increase in personnel-related costs, primarily from increases in salaries, stock-based compensation expense and severance, partially offset by a $0.4 million decrease in professional services costs.

Interest and Other Income, net. Interest and other income, net decreased $0.2 million, or 40%, from $0.6 million for the three months ended March 31, ~~2020.~~2020 to $0.4 million for the three months ended March 31, 2021. The decrease of ~~$0.1~~$0.2 million was due to $0.6 million in lower interest income generated from lower returns and lower balances on our ~~investments.~~investments, partially offset by a $0.4 million gain related to the remeasurement of our lease liability.

As of March 31, ~~2020,~~2021, we had cash, cash equivalents and short-term investments totaling ~~$138.1~~$102.9 million. Our operations have been financed by net proceeds from the sale of shares of our capital stock and payments from the Incyte Collaboration Agreement.

In August ~~2017,~~2020, we filed a shelf registration statement on Form S-3 with the Securities and Exchange Commission which permits the offering, issuance and sale by us of up to a maximum aggregate offering price of ~~$250.0~~$250 million of our common ~~stock~~.stock. As of March 31, ~~2020, $124.1~~2021, $240.3 million of our common stock remained available for sale, of which ~~$50~~$65.3 million may be issued and sold pursuant to an at-the-market offering program, or ATM program, for sales of our common stock under a sales agreement with Jefferies LLC, subject to certain conditions as specified in the sales agreement.

~~In April 2020,~~For the three months ended March 31, 2021, we sold ~~5,750,000~~3,197,166 shares of our common stock ~~pursuant to~~under our ATM program at an ~~underwriting agreement with~~ ~~Citigroup Global Markets, Inc.,~~ ~~at a public offering~~average price ~~of $6.25~~ per share of $3.04, for gross proceeds of ~~$33.8~~$9.7 million, resulting in net proceeds of ~~approximately $33.5~~$9.5 million after deducting underwriting fees and offering ~~expenses.~~expenses.

Our primary uses of cash are to fund operating expenses, primarily research and development expenditures. Cash used to fund operating expenses is impacted by the timing of when we pay these expenses, as reflected in the change in our outstanding accounts payable and accrued expenses.

We believe that our existing cash, cash equivalents and investments as of March 31, ~~2020~~2021 will be sufficient for us to meet our current operating plan for at least the twelve-month period following the filing of our March 31, ~~2020~~2021 Form 10-Q. However, our

forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially based on a number of factors including the extent and magnitude of the impact from the COVID-19 pandemic, in particular the challenges associated with opening new and enrolling existing clinical studies. In order to complete the process of obtaining regulatory approval for our product candidates and to

build the sales, marketing and distribution infrastructure that we believe will be necessary to commercialize our product candidates, if approved, we will require substantial additional funding.

We have based our projections of operating capital requirements on assumptions that may prove to be incorrect and we may use all of our available capital resources sooner than we expect. Because of the numerous risks and uncertainties associated with research, development and commercialization of pharmaceutical products, we are unable to estimate the exact amount of our operating capital requirements. Our future funding requirements will depend on many factors, including, but not limited to:

We plan to continue to fund our operations and capital funding needs ~~through reimbursement of expenses under our existing collaboration agreements and~~ through equity and/or debt financing. We may also consider further collaborations or selectively partnering for clinical development and commercialization. The sale of additional equity would result in additional dilution to our stockholders. The incurrence of debt financing would result in debt service obligations and the instruments governing such debt could provide for operating and financing covenants that would restrict our operations. If we are not able to secure adequate additional funding we may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. The continued spread of COVID-19 and uncertain market conditions may limit our ability to access capital. Any of these actions could harm our business, results of operations and future prospects.

	Three Months						Three Months
	Ended March 31,						Ended March 31,
	2020			2019			2021			2020
	(in thousands)						(in thousands)
Cash used in operating activities	$	(27,015	)	$	(20,624	)	$	(22,002	)	$	(27,015	)
Cash (used in) provided by investing activities	$	(614	)	$	8,996
Cash provided by (used in) investing activities							$	6,500		$	(614	)
Cash provided by financing activities	$	7,659		$	1,154		$	9,537		$	7,659

Cash used in ~~operations~~operating activities was ~~($27.0)~~$22.0 million for the three months ended March 31, ~~2020,~~2021, compared to ~~($20.6)~~$27.0 million for the three months ended March 31, ~~2019.~~2020. The ~~increase~~decrease of ~~$6.4~~$5.0 million in cash used in ~~operations~~operating activities mainly related to ~~increased clinical trial~~decreased research and development ~~activities,~~costs, primarily related to our ~~teleglenastat and CB-280 programs.~~telaglenstat program.

Cash provided by (used in) ~~provided by~~ investing activities was ~~($0.6)~~$6.5 million and ~~$9.0~~($0.6) million for the three months ended March 31, ~~2020~~2021 and ~~2019,~~2020, respectively, and for both periods primarily related to the purchase and the sale and maturity of investments.

Cash provided by financing activities was ~~$7.7~~$9.5 million and ~~$1.2~~$7.7 million for the three months ended March 31, 2021 and 2020, respectively. For the three months ended March 31, 2021, we received $9.5 million in net proceeds from the sale and ~~2019, respectively.~~issuance of common stock related to our at-the-market offering program. For the three months ended March 31, 2020, we received $7.4 million in net proceeds from the sale and issuance of common stock related to our at-the-market offering program and $0.3 million in net proceeds from the issuance of common stock upon the exercise of stock options from employee stock plan purchases. ~~For the three months ended March 31, 2019, we received $1.2 million in net proceeds from the sale and issuance of common stock related to our at-the-market offering program.~~

On March 8, 2021, we amended our facility lease to reduce our rentable area from approximately 54,000 square feet to approximately 34,000 square feet. The related reduction in rent was effective January 1, 2021. Please refer to Note 6 to our unaudited condensed consolidated financial statements appearing under Part I, Item 1 for a discussion of our amended lease.

There have been no other material changes to the contractual obligations during the three months ended March 31, ~~2020,~~2021, as compared to those disclosed in our Annual Report on Form 10-K for the year ended December 31, ~~2019.~~2020.

During ~~2019~~2020 and the three months ended March 31, ~~2020,~~2021, we did not have any off-balance sheet arrangements.

Please refer to Note 2 to our unaudited condensed consolidated financial statements appearing under Part I, Item 1 for a discussion of recent accounting pronouncements.

During the three months ended March 31, ~~2020,~~2021, there were no material changes to our market risk disclosures as set forth in Part II, Item 7A, “Quantitative and Qualitative Disclosures About Market Risk” in our Annual Report on Form 10-K for the year ended December 31, ~~2019.~~ 2020.

As of March 31, ~~2020,~~2021, management, with the participation of our ~~President and~~ Chief Executive Officer ~~(who serves as our principal executive officer~~ and ~~principal financial officer),~~Chief Financial Officer, performed an evaluation of the effectiveness of the design and operation of our disclosure controls and procedures as defined inRules 13a-15(e) and 15d-15(e) of the Exchange Act. Our disclosure controls and procedures are designed to ensure that information required to be disclosed in the reports we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission’s rules and forms, and that such information is accumulated and communicated to our management, including ~~our President~~the Chief Executive Officer and Chief ~~Executive~~Financial Officer, to allow timely decisions regarding required disclosures.

Any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objective and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on this evaluation, our ~~President~~Chief Executive Officer and our Chief ~~Executive~~Financial Officer concluded that, as of March 31, ~~2020,~~2021, the design and operation of our disclosure controls and procedures were effective at a reasonable assurance level.

There were no changes in our internal control over financial reporting during the three months ended March 31, ~~2020,~~2021, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

From time to time, we may become involved in legal proceedings relating to claims arising from the ordinary course of business. Our management believes that there are currently no claims or actions pending against us, the ultimate disposition of which could have a material adverse effect on our results of operations, financial condition or cash flows.

Our business involves significant risks, some of which are described below. You should carefully consider the following risk factors, in addition to the other information contained in this report on Form 10-Q, including our financial statements and related notes and the section of this report titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations”. The occurrence of any of the events or developments described in the following risk factors and the risks described elsewhere in this report could harm our business, financial condition, results of operations, cash flows, the trading price of our common stock and our growth prospects. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. This report on Form 10-Q also contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in the forward-looking statements as a result of factors that are described below and elsewhere in this report. The risks relating to our business set forth in our Annual Report on Form 10-K, filed with the SEC, are set forth below and are unchanged substantively as of March 31, ~~2020,~~2021, except for those risks designated by an asterisk (*).

Our business is subject to numerous risks and uncertainties, including those highlighted in the section titled “Risk Factors” immediately following this summary. These risks include, among others, the following:

We have incurred significant operating losses since our inception and anticipate that we will continue to incur substantial operating losses for the foreseeable future. We may never achieve or maintain profitability.*

Since our inception, we have incurred significant operating losses. Our net loss was ~~$89.9~~$90.1 million and ~~$24.4~~$20.4 million for the year ended December 31, ~~2019,~~2020, and the three months ended March 31, ~~2020,~~2021, respectively. As of March 31, ~~2020,~~2021, we had an accumulated deficit of ~~$310.5~~$396.6 million. To date, we have financed our operations through sales of our capital stock and payments from the Incyte Collaboration Agreement. We have devoted substantially all of our financial resources and efforts to research and development. We expect that it may be ~~a couple of~~many years, if ever, before we receive regulatory approval and have a product candidate ready for commercialization. We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. Our net losses may fluctuate significantly from quarter to quarter and year to year. We anticipate that our expenses will increase substantially if and as we:

We have never generated any revenue from product sales and may never be profitable. To become and remain profitable, we and/or our collaborators must develop and eventually commercialize one or more products with significant market potential. This will require us to be successful in a range of challenging activities, including completing preclinical studies and clinical trials of our product candidates, obtaining marketing approval for these product candidates, manufacturing, marketing and selling those product candidates for which we may obtain marketing approval, and satisfying any post-marketing requirements. We may never succeed in these activities and, even if we do, may never generate revenue that is significant or large enough to achieve profitability. Our failure to become and remain profitable would decrease the value of the company and could impair our ability to raise capital, maintain our research and development efforts, expand our business or continue our operations. A decline in the value of our company could also cause you to lose all or part of your investment.

We will need substantial additional funding. If we are unable to raise capital when needed, we would be forced to delay, reduce or eliminate our product development programs or commercialization efforts.

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the research and development of, continue and initiate clinical trials of, potentially prepare for commercial launch of, and seek marketing approval for our product candidates, specifically telaglenastat, ~~and INCB001158,~~ and as we become obligated to make milestone payments pursuant to our outstanding license agreement. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution of the approved product.

Identifying potential product candidates and conducting preclinical studies and clinical trials are time consuming, expensive and uncertain processes that take years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales for any of our current or future product candidates. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenue, if any, will be derived from sales of products that may not be commercially available for many years, if at all.

We do not have any material committed external source of funds or other support for our development efforts other than the Incyte Collaboration Agreement for the development and commercialization of small molecule arginase inhibitors in hematology and oncology indications, including INCB001158, which agreement is terminable by Incyte for convenience or following our uncured breach. If the Incyte Collaboration Agreement is terminated, we would need to obtain substantial additional sources of funding to develop INCB001158 as currently contemplated.If such additional funding is not available on favorable terms or at all, we may need to delay or reduce the scope of our INCB001158 development program or dedicate resources allocated to other programs to fund INCB001158. We may also need to grant rights in the United States, as well as outside the United States, to INCB001158 to one or more partners.

Accordingly, we will need substantial additional funding in connection with our continuing operations and to achieve our goals. We expect that our existing cash, cash equivalents, and investments will be sufficient to enable us to meet our current operating plan for at least the next 12 months. However, our existing cash, cash equivalents and investments may prove to be insufficient for these activities. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and development programs or future commercialization efforts. Adequate additional financing may not be available to us on acceptable terms, or at all. In addition, we may seek additional financing due to favorable market conditions or strategic considerations, even if we believe we have sufficient funds for our operating plans.

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through a combination of equity and debt financings, as well as entering into new collaborations, strategic alliances and licensing arrangements. We do not have any committed external source of funds, other than our collaborations, which are limited in scope and duration. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a common stockholder. Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, and may be secured by all or a portion of our assets. If we raise funds by entering into new collaborations, strategic alliances or licensing arrangements in the future with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product

candidates or to grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or through collaborations, strategic alliances or licensing arrangements when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Our short operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

We were founded in March 2010 and our operations to date have been limited to organizing and staffing our company, business planning, raising capital, developing our technology, identifying potential product candidates, undertaking preclinical studies and commencing Phase 1 and 2 clinical trials of our product candidates. CB-280 ~~INCB001158,~~ and telaglenastat are currently being evaluated in Phase 1 ~~Phase 1/2,~~ and Phase 2 clinical trials, respectively. All of our other programs are in research and preclinical development. We have not yet demonstrated our ability to successfully complete any clinical trials, including large-scale, pivotal clinical trials required for regulatory approval of our product candidates, obtain marketing approvals, manufacture a commercial scale product, or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful commercialization. Typically, it takes many years to develop one new product from the time it is discovered to when it is commercially available. Consequently, any predictions made about our future success or viability may not be as accurate as they could be if we had a longer operating history or if we had product candidates in advanced clinical trials.

In addition, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors that may alter or delay our plans. WeIf a product candidate is approved, we will need ~~to continue~~ to transition from a company with a research and development focus to ~~a company capable of supporting development activities and, if a product candidate is approved,~~ a company capable of supporting successful commercial activities. We may not be successful in any step in such a transition.

Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.*

Sections 382 and 383 place a limitation on the amount of taxable income which can be offset by carryforward tax attributes, such as net operating losses or tax credits, after a change in control. Generally, after a change in control, a loss corporation cannot deduct carryforward tax attributes in excess of the limitation prescribed by Section 382 and 383. Therefore, certain of the Company's carryforward tax attributes may be subject to an annual limitation regarding their utilization against taxable income in future periods. As a result of the Company's IPO in 2014, the Company triggered an "ownership change" as defined in Internal Revenue Code Section 382 and related provisions. Additionally, due to stock acquired by investors and reported under Section 13(g), the Company believes that an “ownership change” occurred during 2018, as well. Subsequent ownership changes since 2018 may subject the Company to annual limitations of its net operating loss and credit carryforwards. Such annual limitation could result in the expiration of the net operating loss and credit carryforwards before utilization.

Furthermore, our ability to use our net operating losses and other tax attributes to offset potential future taxable income and related income taxes that would otherwise be due is dependent upon our generation of future taxable income before the expiration dates of the net operating losses, and we cannot predict with certainty when, or whether, we will generate sufficient taxable income to use all of our net operating losses. Federal net operating losses generated prior to 2018 will continue to be governed by the net operating loss tax rules as they existed prior to the adoption of the ~~new~~ Tax Cuts and Jobs Act of 2017, or Tax Act, which means that generally they will expire 20 years after they were generated if not used prior thereto. Under the Tax Act, as modified by the Coronavirus Aid, Relief, and Economic Security Act, or CARES Act, signed into law on March 27, 2020, federal net operating losses incurred in 2018 and in future years may be carried forward indefinitely, but the deductibility of such federal net operating losses will be limited to 80% of current year taxable income ~~starting in 2021. Because we had no~~for taxable ~~income in prior~~ years ~~we do not anticipate carrying back any of our operating losses as permitted by the CARES Act.~~beginning after December 31, 2020.

Our effective tax rate may fluctuate, and tax authorities may disagree with our positions and conclusions regarding certain tax positions, resulting in unanticipated costs, taxes or non-realization of expected benefits.

Our effective tax rate may be different than experienced in the past due to numerous factors, including passage of the newly enacted federal income tax law, changes in the mix of our profitability between jurisdictions in which we are or may become subject to tax, the results of examinations and audits of our tax filings, our inability to secure or sustain acceptable agreements with tax authorities, changes in accounting for income taxes and changes in tax laws. Any of these factors could cause us to experience an effective tax rate significantly different from previous periods or our current expectations and may result in tax obligations in excess of amounts accrued in our financial statements.

A tax authority may disagree with tax positions that we have taken, which could result in increased tax liabilities. For example, a tax authority could assert that we are subject to tax in a jurisdiction where we believe we have not established a taxable nexus, often referred to as a “permanent establishment” under international tax treaties, and such an assertion, if successful, could increase our expected tax liability in one or more jurisdictions. A tax authority may take the position that material income tax liabilities, interest and penalties are payable by us, in which case, we expect that we might contest such assessment. Contesting such an assessment may

be lengthy and costly and if we were unsuccessful in disputing the assessment, the implications could increase our anticipated effective tax rate, where applicable.

Our business, operations and clinical development plans and timelines are currently adversely affected by and could be adversely affected in the future by the effects of health epidemics, including the recent COVID-19 pandemic, on the manufacturing, clinical trial and other business activities performed by us or by third parties with whom we conduct business, including our contract manufacturers, Clinical Research Organizations, or CROs, shippers and others. *

Our business could be adversely affected in the future by health epidemics wherever we have clinical trial sites or other business operations. In addition, health epidemics could cause significant disruption in the operations of third-party manufacturers, CROs and other third parties upon whom we rely. For example, in December 2019, a novel strain of coronavirus, SARS-CoV-2, causing a disease referred to as COVID-19, was reported to have surfaced in Wuhan, China. Since then, COVID-19 has spread to multiple countries worldwide, including the United States. In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic, and the U.S. government imposed travel restrictions on travel between the United States, Europe and certain other countries. Further, the President of the United States declared the COVID-19 pandemic a national emergency and invoked powers under the Stafford Act, the legislation that directs federal emergency disaster response, and under the Defense Production Act, the legislation that facilitates the production of goods and services necessary for national security and for other purposes. Similarly, the State of California declared a state of emergency related to the spread of COVID-19, and the Governor of California and other health officials in California have announced aggressive orders, health directives and recommendations to reduce the spread of the disease. On March 16, 2020, the Health Officer of San Mateo County, the county in which our headquarters is located, issued a “Shelter in Place” Order requiring, among other things, the closure of all non-essential businesses. Further, the Governor of California issued an executive order directing that all non-essential businesses close their physical operations and implement work-from-home schedules, effective as of March 19, 2020. We have implemented work-from-home policies for all employees. The effects of the executive order and our work-from-home policies may continue to negatively impact productivity, disrupt our business and delay our clinical programs and timelines, the magnitude of which will depend, in part, on the length and severity of the restrictions and other limitations on our ability to conduct our business in the ordinary course.For example, the CANTATA trial was fully enrolled in October 2019, and we previously advised that we planned to report top-line efficacy and safety data from the trial in the late third quarter or fourth quarter of 2020. In light of delays associated with COVID-19, top-line data was announced in early first quarter 2021. These and similar, and perhaps more severe, disruptions in our operations could negatively impact our business, operating results and financial condition.

We depend on a worldwide supply chain to manufacture products used in our preclinical studies and clinical trials. Quarantines, shelter-in-place and similar government orders, or the expectation that such orders, shutdowns or other restrictions could occur, whether related to COVID-19 or other infectious diseases, could impact personnel at third-party manufacturing facilities in the United States and other countries, or the availability or cost of materials, which could disrupt our supply chain.

If our relationships with our suppliers or other vendors are terminated or scaled back as a result of the COVID-19 pandemic or other health epidemics, we may not be able to enter into arrangements with alternative suppliers or vendors or do so on commercially reasonable terms or in a timely manner. Switching or adding additional suppliers or vendors involves substantial cost and requires management time and focus. In addition, there is a natural transition period when a new supplier or vendor commences work. As a result, delays may occur, which could adversely impact our ability to meet our desired clinical development and any future commercialization timelines. Although we carefully manage our relationships with our suppliers and vendors, there can be no assurance that we will not encounter challenges or delays in the future or that these delays or challenges will not harm our business.

In addition, our preclinical studies and clinical trials have been and may continue to be affected by the COVID-19 pandemic. Clinical site initiation, patient enrollment and activities that require visits to clinical sites, including data monitoring, have been and

may continue to be delayed due to prioritization of hospital resources toward the COVID-19 pandemic or concerns among patients about participating in clinical trials during a pandemic. Some patients may have difficulty following certain aspects of clinical trial protocols if quarantines impede patient movement or interrupt healthcare services. Similarly, if we are unable to successfully recruit and retain patients and principal investigators and site staff who, as healthcare providers, may have heightened exposure to COVID-19 or experience additional restrictions by their institutions, city, or state our clinical trial operations could be adversely impacted.

The spread of COVID-19, which has caused a broad impact globally, may materially affect us economically. While the potential economic impact brought by, and the duration of, COVID-19 may be difficult to assess or predict, a widespread pandemic could result in significant disruption of global financial markets, reducing our ability to access capital, which could in the future negatively affect our liquidity. In addition, a recession or market correction resulting from the spread of COVID-19 could materially affect our business and the value of our common stock.

The global pandemic of COVID-19 continues to evolve rapidly. The ultimate impact of the COVID-19 pandemic or a similar health epidemic is highly uncertain and subject to change. We do not yet know the full extent of potential delays or impacts on our business, our clinical trials, healthcare systems or the global economy as a whole. However, these effects could have a material impact on our operations, and we continue to monitor the COVID-19 situation closely.

Our approach to the discovery and development of product candidates that target tumor metabolism and tumor immunology is unproven and may never lead to marketable products.

Our scientific approach focuses on using our understanding of cellular metabolic pathways and the role of glutaminase in these pathways, as well as the role of arginase in the anti-tumor immune response, to identify molecules that are potentially promising as therapies for cancer indications. Any product candidates we develop may not effectively modulate metabolic or immunology pathways. The scientific evidence to support the feasibility of developing product candidates based on inhibiting tumor metabolism or impacting the anti-tumor immune response are both preliminary and limited. Although preclinical studies suggest that inhibiting glutaminase can suppress the growth of certain cancer cells, to date no company has translated this mechanism into a drug that has received marketing approval. Even if we are able to develop a product candidate in preclinical studies, we may not succeed in demonstrating the safety and efficacy of the product candidate in human clinical trials. Our expertise in cellular metabolic pathways, the role of glutaminase in these pathways, and the role of arginase in the anti-tumor immune response may not result in the discovery and development of commercially viable products to treat cancer.

Our drug discovery and development efforts might not generate successful product candidates.

We have invested a significant portion of our efforts and financial resources in the identification of our most advanced product candidates, telaglenastat, INCB001158 and CB-280, which are being evaluated in Phase 2, Phase 1/2 and Phase 1 clinical trials, respectively. Although we believe the Phase 2 CANTATA trial, if it meets its primary endpoint, may be sufficient to support approval of a New Drug Application by FDA, the FDA may disagree and we may be required to conduct additional trials to support the approval of telaglenastat in combination for the second or third line treatment of renal cell carcinoma. We have entered into the Incyte Collaboration Agreement for the development and commercialization of INCB001158. Pursuant to ~~our~~the agreement, we ~~collaborate~~and Incyte have collaborated on, and ~~co-fund~~co-funded the development of, ~~INCB001158~~the licensed products for hematology and oncology indications, including INCB001158, with Incyte bearing 70% and ~~unless~~Calithera bearing 30% of global development costs. Effective September 30, 2020, we ~~opt~~have opted out of our ~~co-funding obligation,~~co-development obligations and as a result, Incyte will ~~fund 70% of global development~~pay all costs ~~and we will be responsible for the remaining 30%.~~to develop INCB001158 or any other licensed products. All of our other programs are in research and preclinical development. Telaglenastat and INCB001158 will be developed for use in combination with other approved therapies, and as such, we will be dependent upon the continued marketing availability of the drugs that are used in combination with them. As a result, the timing and costs of the regulatory paths we will follow and marketing approvals remain uncertain. Our ability to generate product revenue, which may not occur for many years, if ever, will depend heavily on the successful development and eventual commercialization of telaglenastat and INCB001158. The success of telaglenastat, INCB001158 and any other product candidates we may develop will depend on many factors, including the following:

If we do not accomplish one or more of these goals in a timely manner, or at all, we could experience significant delays or an inability to successfully commercialize our product candidates, which would harm our business.

We may not be successful in our efforts to identify or discover potential product candidates for clinical development.

Our drug discovery efforts may not be successful in identifying compounds that are useful in treating cancer. Our research programs may initially show promise in identifying potential product candidates, yet fail to yield product candidates for clinical development for a number of reasons. In particular, our research methodology used may not be successful in identifying compounds with sufficient potency or bioavailability to be potential product candidates. In addition, our potential product candidates may, on further study, be shown to have harmful side effects or other negative characteristics.

Research programs to identify new product candidates require substantial technical, financial and human resources. We may choose to focus our efforts and resources on potential product candidates that ultimately prove to be unsuccessful. If we are unable to identify suitable compounds for preclinical and clinical development, we will not be able to generate product revenue, which would harm our financial position and adversely impact our stock price.

If clinical trials of our product candidates fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our product candidates.

Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must complete preclinical development and ~~in the case of INCB001158, together with Incyte,~~ then conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidates in humans. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is uncertain as to outcome. A failure of one or more clinical trials could occur at any stage of testing. The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a particular clinical trial do not necessarily predict final results of that trial. For example, our CANTATA trial of telaglenastat in RCC did not meet the primary endpoint of PFS despite earlier encouraging results in this indication in a Phase 1b trial.

Moreover, preclinical and clinical data are often susceptible to multiple interpretations and analyses. Many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their products.

We may experience numerous unforeseen events during, or as a result of, preclinical testing or clinical trials that could delay or prevent our ability to receive marketing approval or commercialize our product candidates, including that:

If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we may:

Product development costs will also increase if we experience delays in testing or in receiving marketing approvals. We do not know whether any clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates, could allow our competitors to bring products to market before we do, and could impair our ability to successfully commercialize our product candidates, any of which may harm our business and results of operations.

If we experience delays or difficulties in enrolling patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented.

We may not be able to initiate or continue clinical trials for our product candidates if we are unable to identify and enroll a sufficient number of eligible patients to participate in these trials as required by the U.S. Food and Drug Administration, or the FDA, or analogous regulatory authorities outside the United States. In addition, some of our competitors may have ongoing clinical trials for product candidates that would treat the same indications as our product candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ product candidates. Patient enrollment is also affected by other factors, including:

Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or may require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates, which would cause the value of our company to decline and limit our ability to obtain additional financing.

If serious adverse effects or unexpected characteristics of our product candidates are identified during development, we may need to abandon or limit our development of some or all of our product candidates.

We are currently evaluating CB-280, INCB001158, and telaglenastat in Phase 1, Phase 1/2, and Phase 2 clinical trials, respectively. All our other programs are in research and preclinical development and their risk of failure is high. It is impossible to predict when or if any of our product candidates will prove effective or safe in humans or will receive marketing approval. Adverse events or undesirable side effects caused by, or other unexpected properties of, our product candidates could cause us, any current or future collaborators, an institutional review board or regulatory authorities to interrupt, delay or halt clinical trials of one or more of our product candidates and could result in a more restrictive label, or the delay or denial of marketing approval by the FDA or comparable foreign regulatory authorities. If adverse effects were to arise in patients being treated with any of our product candidates, it could require us to halt, delay or interrupt clinical trials of such product candidate or adversely affect our ability to obtain requisite approvals to advance the development and commercialization of such product candidate. If our product candidates are associated with undesirable side effects or have characteristics that are unexpected, we may need to abandon their development or limit development to certain uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. Many agents that initially showed promise in early stage testing for treating cancer or other diseases have later been found to cause side effects that prevented further development of the agent.

We are in early clinical trials with telaglenastat and INCB001158 and we have seen several adverse events, or AEs, deemed possibly or probably related to study drug in each of those programs. For example, in our evaluation of telaglenastat with nivolumab, during the dose escalation of the combination therapy, there was one report of dose limiting Grade 3 ALT increase. We have treated an insufficient number of patients to fully assess the safety of telaglenastat and INCB001158 and, as these trials progress, we may experience frequent or severe adverse events. Our ongoing and planned trials for telaglenastat and our and Incyte’s ongoing and

planned trials for INCB001158 may fail due to safety issues, and we may need to abandon development of telaglenastat or INCB001158. Our other research programs may fail due to preclinical or clinical safety issues, causing us to abandon or delay the development of a product candidate from these programs.

Results of preclinical studies and early clinical trials may not be predictive of results of future clinical trials.

The outcome of preclinical studies and early clinical trials may not be predictive of the success of later clinical trials, and interim results of clinical trials do not necessarily predict success in future clinical trials. Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in earlier development, and we could face similar setbacks. The design of a clinical trial can determine whether its results will support approval of a product and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. We may experience delays in designing and executing clinical trials to support marketing approval. In addition, preclinical and clinical data are often susceptible to varying interpretations and analyses. Many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval for the product candidates. Even if we, or our current and future collaborators, believe that the results of clinical trials for our product candidates warrant marketing approval, the FDA or comparable foreign regulatory authorities may disagree and may not grant marketing approval of our product candidates.

In some instances, there can be significant variability in safety or efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial procedures set forth in protocols, differences in the size and type of the patient populations, changes in and adherence to the dosing regimen and other clinical trial protocols and the rate of dropout among clinical trial participants. If we fail to receive positive results in clinical trials of our product candidates, the development timeline and regulatory approval and commercialization prospects for our most advanced product candidates, and, correspondingly, our business and financial prospects would be negatively impacted.

We may expend our limited resources to pursue a particular product candidate or indication and fail to capitalize on product candidates or indications that may be more profitable or for which there is a greater likelihood of success.

We have limited financial and managerial resources. As a result, we may forego or delay pursuit of opportunities with other product candidates or for other indications that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable products. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements, including our agreement with Incyte, in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate. In addition, under our agreement with Incyte, Incyte has the right to commercialize INCB001158 in hematology and oncology indications. If Incyte does not successfully commercialize INCB001158, we may be unable to realize the full value from our collaboration with Incyte.

Even if any of our product candidates receives marketing approval, we or others may later discover that the product is less effective than previously believed or causes undesirable side effects that were not previously identified, which could compromise our ability, or that of any future collaborators, to market the product.

Clinical trials of our product candidates are conducted in carefully defined sets of patients who have agreed to enter into clinical trials. Consequently, it is possible that our clinical trials, or those of any future collaborator, may indicate an apparent positive effect of a product candidate that is greater than the actual positive effect, if any, or alternatively fail to identify undesirable side effects. If, following approval of a product candidate, we, or others, discover that the product is less effective than previously believed or causes undesirable side effects that were not previously identified, any of the following adverse events could occur:

Even if any of our product candidates receive marketing approval, they may fail to achieve the degree of market acceptance by health care professionals, patients, third party payors and others in the medical community necessary for commercial success.

If any of our product candidates receive marketing approval, they may nonetheless fail to gain sufficient market acceptance by health care professionals, patients, third party payors and others in the medical community for us to achieve commercial success. For example, current cancer treatments like chemotherapy and radiation therapy for certain diseases and conditions are well established in the medical community, and doctors may continue to rely on these treatments. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant product revenue to become profitable. The degree of market acceptance of our product candidates, if approved for commercial sale, will depend on a number of factors, including:

If, in the future, we are unable to establish adequate sales and marketing capabilities or to selectively enter into agreements with third parties to sell and market our product candidates, we may not be successful in commercializing our product candidates if and when they are approved.

We do not have a sales orand marketing infrastructure ~~and have no experience in the sale, marketing or distribution of pharmaceutical products.~~to support any future commercialization efforts. To achieve commercial success for any approved product for which we retain sales and marketing responsibilities, we must either develop a robust sales and marketing organization and/or outsource these functions to other third parties. For our small molecule arginase inhibitors in hematology and oncology indications, including INCB001158, ~~unless we establish our own sales and marketing capabilities,~~ we will be ~~significantly~~ dependent on Incyte’s sales and marketing infrastructure to effectively commercialize these products. In the future, we may choose to build a focused sales and marketing infrastructure to sell some of our product candidates, if and when they are ~~approved.~~approved, excluding INCB001158.

There are risks involved both with establishing our own sales and marketing capabilities and with entering into arrangements with third parties to perform these services. For example, recruiting and training a sales force is expensive and time consuming and could delay any product launch. If the commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

Factors that may inhibit our efforts to commercialize our product candidates on our own include:

If we enter into arrangements with third parties to perform sales, marketing and distribution services, our product revenue or the profitability of these product revenue to us may be lower than if we were to market and sell any products that we develop ourselves. In addition, we may not be successful in entering into arrangements with third parties to sell and market our product candidates or may be unable to do so on terms that are favorable to us. We may have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our products effectively. If we do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.

We face substantial competition, which may result in others discovering, developing or commercializing products before or more successfully than we do.

The development and commercialization of new drug products is highly competitive. Research and discoveries by others may result in breakthroughs which may render our products obsolete even before they generate any revenue. We face competition with respect to our current product candidates, and will face competition with respect to any product candidates that we may seek to develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide. There are a number of large pharmaceutical and biotechnology companies that currently market and sell products or are pursuing the development of products for the treatment of the cancer indications for which we are focusing our product development efforts. Some of these competitive products and therapies are based on scientific approaches that are the same as or similar to our approach and others are based on entirely different approaches. Potential competitors also include academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization.

We are developing our product candidates for the treatment of various cancers. There are a variety of available drug therapies marketed for cancer. In many cases, these drugs are administered in combination to enhance efficacy. Some of the currently approved drug therapies are branded and subject to patent protection, and others are available on a generic basis. Many of these approved drugs are well-established therapies and are widely accepted by health care professionals, patients and third-party payors. Insurers and other third-party payors may also encourage the use of generic products. We expect that if our product candidates are approved, they will be priced at a significant premium over competitive generic products. This may make it difficult for us to achieve our business strategy of using our product candidates in combination with existing therapies or replacing existing therapies with our product candidates.

There are also a number of product candidates in preclinical and clinical development by third parties to treat cancer by targeting cellular metabolism. Our principal competitors in the fields of tumor immunology, tumor metabolism, and/or other product candidates in development for advanced cancer treatment include Agios Pharmaceuticals, Inc., Arcus Biosciences, Inc., AstraZeneca plc, Boehringer Ingelheim GmbH, Bayer Pharma AG, Bristol-Myers Squibb Company, Celgene Corporation, Corvus Pharmaceuticals, Inc., Dracen Pharmaceuticals, Inc., Eisai Co., Ltd., Eli Lilly and Company, GlaxoSmithKline plc, ~~Immunomedics Inc.,~~ Incyte Corporation, ~~Ipsen,~~ iTeos Therapeutics SA, Merck & Co., Merck KGaA, Nektar Therapeutics, Novartis International AG, Pfizer Inc, Roche Holdings AG and its subsidiary Genentech, Inc., and Takeda Pharmaceutical Co., Ltd.~~, and Xynomic Pharmaceuticals, Inc.~~

Our primary competitors in the field of Cystic Fibrosis include AbbVie, Inc., ~~AIT Therapeutics,~~Beyond Air Inc., Corbus Pharmaceuticals Holdings, Inc., ~~Flatley Discovery Lab, LLC, Galapagos NV,~~ Novartis AG, Novoteris, LLC, Proteostatis Therapeutics, Inc., ~~ProQR Therapeutics NV,~~ Translate Bio, Inc., and Vertex Pharmaceuticals, Inc.

Our competitors may develop products that are more effective, safer, more convenient or less costly than any that we are developing or that would render our product candidates obsolete or non-competitive. In addition, our competitors may discover biomarkers that more efficiently measure metabolic pathways than our methods, which may give them a competitive advantage in developing potential products. Our competitors may also obtain marketing approval from the FDA or other regulatory authorities for their products sooner than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market. Many of our competitors have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller and other early stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These third parties may compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

Even if we are able to commercialize any product candidates, these products may become subject to unfavorable pricing regulations, third-party coverage and reimbursement practices or healthcare reform initiatives, which would harm our business.

The regulations that govern marketing approvals, pricing and reimbursement for new drugs vary widely from country to country. In the United States, new and future legislation may significantly change the approval requirements in ways that could involve additional costs and cause delays in obtaining approvals. Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period begins after marketing or product-licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control even after initial marketing approval is granted. As a result, we might obtain marketing approval for a drug in a particular country, but then be subject to price regulations that delay its commercial launch, possibly for lengthy time periods, and negatively impact the revenue we are able to generate from the sale of the drug in that country. Adverse pricing limitations may hinder our ability to commercialize and generate revenue from one or more product candidates, even if our product candidates obtain marketing approval.

Our ability to commercialize any product candidates successfully also will depend in part on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from government health programs, private health insurers and other organizations. Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels. A significant trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of payment for particular medications. Increasingly, third-party payors are requiring that drug companies provide them with predetermined discounts from list prices and are challenging the prices charged for medical products. ~~Reimbursement~~Coverage may not be available for any product that we commercialize and, if ~~reimbursement~~coverage is available, the level of reimbursement may not be sufficient. Reimbursement may impact the demand for, or the price of, any product candidate for which we obtain marketing approval. If reimbursement is not available or is available only to limited levels, we may not be able to successfully commercialize any product candidate for which we obtain marketing approval.

There may be significant delays in obtaining reimbursement for newly approved products, and coverage may be more limited than the purposes for which the product is approved by the FDA or similar regulatory authorities outside the United States. Moreover, eligibility for ~~reimbursement~~coverage does not imply that any product will be paid for in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new drugs, if applicable, may also not be sufficient to cover our costs and may not be made permanent. ~~Reimbursement~~Coverage and reimbursement rates may vary according to the use of the drug and the medical circumstances under which it is used, may be based on reimbursement levels already set for lower cost products or procedures or may be incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the United States. Third-party payors often rely upon Medicare coverage policies and payment limitations in setting their own reimbursement policies. Our inability to promptly obtain coverage and profitable payment rates from both government-funded programs and private payors for any approved products that we develop could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize our approved products and our overall financial condition.

In addition, there has been heightened governmental scrutiny of pharmaceutical pricing practices in light of the rising cost of prescription drugs and biologics. Such scrutiny has resulted in several recent congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. We expect additional healthcare reform initiatives to be adopted in the future, particularly in light of the new presidential administration. We continue to monitor and evaluate the potential impact of these legislative actions and their effect on our business and operations.

Product liability lawsuits against us could cause us to incur substantial liabilities and could limit the commercialization of any product candidates we may develop.

We face an inherent risk of product liability exposure related to the testing of our product candidates in human clinical trials and will face an even greater risk if we commercially sell any products that we may develop after approval. If we cannot successfully defend ourselves against claims that our product candidates caused injuries, we could incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

Although we maintain product liability insurance coverage in the amount of up to $10.0 million per claim and in the aggregate, it may not be adequate to cover all liabilities that we may incur. We anticipate that we will need to increase our insurance coverage as we continue clinical trials and if we successfully commercialize any products. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could harm our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological and radioactive materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees in our workplace, including those resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, chemical, hazardous or radioactive materials.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or production efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

We rely on third parties to conduct our clinical trials and some aspects of our research and preclinical testing and manufacture our product candidates, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials, research or testing.

We currently rely and expect to continue to rely on third parties, such as our collaborators, contract research organizations, clinical data management organizations, medical institutions and clinical investigators, to conduct our clinical trials and to conduct some aspects of our research and preclinical testing. Any of these third parties may terminate their engagements with us at any time. If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we will not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates. Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If we need to enter into alternative arrangements, it would delay our product development activities.

Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial, and that all clinical trial activities conducted by our contract research organizations follow applicable laws and regulations, and are conducted in an ethical and compliant manner. Moreover, the FDA requires us to comply with standards, commonly referred to as Good Clinical Practices, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. We also are required to register ongoing clinical trials and post the results of completed clinical trials on a government sponsored database, available at www.clinicaltrials.gov, within certain timeframes. Failure by us, or any of the third parties working on our behalf, to do the above can result in fines, adverse publicity and civil and criminal sanctions.

We do not have any manufacturing facilities. We currently rely, and expect to continue to rely, on third party manufacturers for the manufacture of our product candidates for preclinical studies and clinical trials and for commercial supply of any of these product candidates for which we obtain marketing approval. To date, we have obtained or plan to obtain materials for telaglenastat, INCB001158 and CB-280 for our current and planned clinical trials from third-party manufacturers. We have engaged third party manufacturers to obtain the active ingredient for telaglenastat, INCB001158 and CB-280 for pre-clinical testing and clinical trials. We do not have a long-term supply agreement with any third-party manufacturers, and we purchase our required drug supply on a purchase order basis.

We may be unable to establish agreements with third-party manufacturers or to do so on acceptable terms. Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks, including:

Third-party manufacturers may not be able to comply with current U.S. Good Manufacturing Practice requirements, or cGMPs, or similar legal and regulatory requirements outside the United States. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates, operating restrictions and criminal prosecutions, any of which could adversely affect supplies of our product candidates and harm our business and results of operations.

Any product that we may develop may compete with other product candidates and products for access to these manufacturing facilities. There are a limited number of manufacturers that operate under cGMPs and that might be capable of manufacturing for us.

Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval. We do not currently have arrangements in place for redundant supply for bulk drug substances. If any one of our current contract manufacturers cannot perform as agreed, we may be required to replace that manufacturer. Although we believe that there are several potential alternative manufacturers who could manufacture our product candidates, we may incur added costs and delays in identifying and qualifying any such replacement.

Our current and anticipated future dependence upon others for the manufacture of our product candidates or products may adversely affect our future profit margins and our ability to commercialize any product candidates that receive marketing approval on a timely and competitive basis.

We also currently rely, and expect to continue to rely, on third parties to store and distribute drug supplies for our clinical trials. Any performance failure on the part of these third parties could delay clinical development or marketing approval of our product candidates or commercialization of our drugs, producing additional losses and depriving us of potential revenue. Although we believe that there are several potential alternative third parties who could store and distribute drug supplies for our clinical trials, we may incur added costs and delays in identifying and qualifying any such replacement.

Our arginase inhibitors program in hematology and oncology indications, including INCB001158, is reliant in part on Incyte for the successful development and commercialization in a timely manner. If Incyte does not devote sufficient resources to INCB001158’s development, is unsuccessful in its efforts, or chooses to terminate its agreement with us, our business, operating results and financial condition will be harmed.*

~~We have~~In January 2017, we and Incyte Corporation entered into the Incyte Collaboration Agreement. Pursuant to the Incyte Collaboration Agreement, ~~under which~~ we ~~have~~ granted Incyte an exclusive, worldwide license to develop and commercialize small molecule arginase inhibitors, including INCB001158, for hematology and oncology indications. We retained rights to certain arginase inhibitors that are not part of the collaboration for specific orphan indications outside of hematology and oncology, including cystic fibrosis. Pursuant to the Incyte Collaboration Agreement, we and Incyte have collaborated on, and co-funded the development of, the licensed products for hematology and oncology indications, including INCB001158, ~~which is currently in Phase 1/2 clinical trials.~~

~~Under the agreement, we and Incyte will jointly conduct and co-fund development of INCB001158,~~ with Incyte ~~leading global development activities. Unless we opt out of our co-funding obligation, Incyte will fund~~bearing 70% and Calithera bearing 30% of global development costs and we will be responsible for the remaining 30%. Should we disagree with Incyte about the clinical development or commercialization strategy, we could escalate the disagreement to our representatives on the Joint Steering Committee for resolution. We and Incyte are obligated to use good faith efforts to resolve such disputes; however, in cases of deadlock, Incyte will have the deciding vote. If the agreement is terminated, other than as a result of our breach, with respect to one or more products or countries, all rights in the terminated products and countries revert to us. costs.

The Incyte collaboration may not be clinically or commercially successful due to a number of important factors, including the following:

In April 2020, we filed a complaint against Incyte in Superior Court of California, San Francisco County, asserting claims for breach of contract arising out of Incyte’s failure to pay two milestone payments we believe are due under the Incyte Collaboration Agreement. Effective September 30, 2020, we have opted out of our co-development obligations and as a result, Incyte will pay all costs to develop INCB001158 or any other licensed products. If we were to terminate our agreement with Incyte due to Incyte’s

breach, or if Incyte were to terminate the agreement without cause, there could be a delay in the return of our rights to INCB001158 and the development and commercialization of INCB001158 would be delayed, curtailed or terminated because we may not have sufficient financial resources or capabilities to continue development and commercialization on our own.

Incyte may enter into one or more transactions with third parties, including a merger, consolidation, reorganization, sale of substantial assets, sale of substantial stock or other change in control, which could divert the attention of its management and adversely affect Incyte’s ability to retain and motivate key personnel who are important to the continued development of the small molecule arginase inhibitor program. In addition, the third party to any such transaction could reprioritize Incyte’s development programs which could delay the development of our programs or cause Incyte to terminate the agreement.

We have in the past and may seek in the future to selectively establish collaborations, and, if we are unable to establish them on commercially reasonable terms, we may have to alter our development and commercialization plans.

Our drug development programs and the potential commercialization of our product candidates will require substantial additional cash to fund expenses. In addition to our collaboration with Incyte, for some of our product candidates, we may decide to collaborate with additional pharmaceutical and biotechnology companies for the development and potential commercialization of those product candidates.

We may also be restricted under existing license agreements from engaging in research and development activities or entering into future agreements on certain terms with potential collaborators. For example, pursuant to our license agreement with Symbioscience, we have agreed not to develop any other arginase inhibitors for use in human healthcare outside of the scope of that agreement. In addition, under our agreement with Incyte, we are not allowed to develop any retained arginase inhibitors (small molecule arginase inhibitors, other than INCB001158, retained by us for research and development in non-hematology/oncology indications) for any indication except specific orphan indications outside of hematology and oncology.

We face significant competition in seeking appropriate collaborators. Whether we reach a definitive agreement for a collaboration will depend, among other things, upon our assessment of the collaborator’s resources and expertise, the terms and conditions of the proposed collaboration and the proposed collaborator’s evaluation of a number of factors. Those factors may include the design or results of clinical trials, the likelihood of approval by the FDA or similar regulatory authorities outside the United States, the potential market for the subject product candidate, the costs and complexities of manufacturing and delivering such product candidate to patients, the potential of competing products, the existence of uncertainty with respect to our ownership of technology, which can exist if there is a challenge to such ownership without regard to the merits of the challenge and industry and market conditions generally. The collaborator may also consider alternative product candidates for similar indications that may be available to collaborate on and whether such a collaboration could be more attractive than the one with us for our product candidate.

Collaborations are complex and time-consuming to negotiate and document. In addition, there have been a significant number of recent business combinations among large pharmaceutical companies that have resulted in a reduced number of potential future collaborators.

If we decide to collaborate with any other third parties in connection with any of our development programs or product candidates, we may not be able to negotiate collaborations on a timely basis, on acceptable terms, or at all. If we are unable to do so, we may have to curtail the development program or the product candidate for which we are seeking to collaborate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or commercialization activities on our own, we may need to obtain additional capital, which may not be available to us on acceptable terms or at all. If we do not have sufficient funds, we may not be able to further develop our product candidates or bring them to market and generate product revenue.

To the extent we enter into any other collaborations, we may depend on such collaborations for the development and commercialization of our product candidates. If those collaborations are not successful, we may not be able to capitalize on the market potential of our product candidates.*

We may selectively seek additional third-party collaborators for the development and commercialization of our product candidates. Our current and any future collaborators for any collaboration arrangements include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies. Pursuant to these arrangements and any potential future arrangements, we will have limited control over the amount and timing of resources that our collaborators dedicate to the development or commercialization of our product candidates. Our ability to generate revenue from these arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements.

Collaborations involving our product candidates, including our collaboration with Incyte, pose many risks to us, including that:

We have in-licensed a portfolio of arginase inhibitors as part of our efforts to develop product candidates for the arginase program, and we are substantially dependent on this in-license for that program. To the extent this in-license is terminated, our business may be harmed.

Our internal computer systems, or those used by our Clinical Research Organizations or other contractors or consultants, may fail or suffer security breaches.

Despite the implementation of security measures, our internal computer systems, and those of our Clinical Research Organizations and other third parties on which we rely, are vulnerable to damage from computer viruses and unauthorized access, malware, natural disasters, fire, terrorism, war and telecommunication, electrical failures, cyber-attacks or cyber-intrusions over the Internet, attachments to emails, persons inside our organization, or persons with access to systems inside our organization. The risk of a security breach or disruption, particularly through cyber-attacks or cyber intrusion, including by computer hackers, foreign governments, and cyber terrorists, has generally increased as the number, intensity and sophistication of attempted attacks and intrusions from around the world have increased. While we have not experienced any such material system failure or security breach to our knowledge to date, if such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our development programs and our business operations. For example, the loss of clinical trial data from completed, ongoing or future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. Likewise, we rely on third parties for the manufacture of our product candidates and to conduct clinical trials, and similar events relating to their computer systems could also have a material adverse effect on our business. To the extent that any disruption or security breach were to result in a loss of, or damage to, our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur liability and the further development and commercialization of our future product candidates could be delayed.

Recent laws and rulings by U.S. courts make it difficult to predict how patents will be issued or enforced in our industry.

Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may have a significant impact on our ability to protect our technology and enforce our intellectual property rights. There have been numerous recent changes to the patent laws and to the rules of the United States Patent and Trademark Office, or the USPTO, which may have a significant impact on our ability to protect our technology and enforce our intellectual property rights. For example, the Leahy-Smith America Invents Act, which was signed into law in 2011, includes a transition from a “first-to-invent” system to a “first-to-file” system, and changes the way issued patents are challenged. Certain changes, such as the institution of inter partes review proceedings, came into effect on September 16, 2012. Substantive changes to patent law associated with the America Invents Act may affect our ability to obtain patents, and, if obtained, to enforce or defend them in litigation or post-grant proceedings, all of which could harm our business.

Furthermore, the patent positions of companies engaged in the development and commercialization of biologics and pharmaceuticals are particularly uncertain. Two cases involving diagnostic method claims and “gene patents” have recently been decided by the Supreme Court. On March 20, 2012, the Supreme Court issued a decision in Mayo Collaborative Services v. Prometheus Laboratories, Inc., or Prometheus, a case involving patent claims directed to measuring a metabolic product in a patient to optimize a drug dosage amount for the patient. According to the Supreme Court, the addition of well-understood, routine or conventional activity such as “administering” or “determining” steps was not enough to transform an otherwise patent ineligible natural phenomenon into patent eligible subject matter. On July 3, 2012, the USPTO issued guidance indicating that process claims directed to a law of nature, a natural phenomenon or an abstract idea that do not include additional elements or steps that integrate the natural principle into the claimed invention such that the natural principle is practically applied and the claim amounts to significantly more than the natural principle itself should be rejected as directed to non-statutory subject matter. On June 13, 2013, the Supreme Court issued its decision in Association for Molecular Pathology v. Myriad Genetics, Inc., or Myriad, a case involving patent claims held by Myriad Genetics, Inc. relating to the breast cancer susceptibility genes BRCA1 and BRCA2. Myriad held that isolated segments of naturally occurring DNA, such as the DNA constituting the BRCA1 and BRCA2 genes, is not patent eligible subject matter, but that complementary DNA, which is an artificial construct that may be created from RNA transcripts of genes, may be patent eligible.

We cannot assure you that our efforts to seek patent protection for our technology and products will not be negatively impacted by the decisions described above, rulings in other cases or changes in guidance or procedures issued by the USPTO. We cannot fully predict what impact the Supreme Court’s decisions in Prometheus and Myriad may have on the ability of life science companies to obtain or enforce patents relating to their products and technologies in the future.

Moreover, although the Supreme Court has held in Myriad that isolated segments of naturally occurring DNA are not patent-eligible subject matter, certain third parties could allege that activities that we may undertake infringe other gene-related patent claims, and we may deem it necessary to defend ourselves against these claims by asserting non-infringement and/or invalidity positions, or pay to obtain a license to these claims. In any of the foregoing or in other situations involving third-party intellectual property rights, if we are unsuccessful in defending against claims of patent infringement, we could be forced to pay damages or be subjected to an injunction that would prevent us from utilizing the patented subject matter. Such outcomes could harm our business.

If we are alleged to infringe intellectual property rights of third parties, our business could be harmed.

Our research, development and commercialization activities may be alleged to infringe patents, trademarks or other intellectual property rights owned by other parties. Certain of our competitors and other companies in the industry have substantial patent portfolios and may attempt to use patent litigation as a means to obtain a competitive advantage. We may be a target for such litigation. Even if our pending patent applications issue, they may relate to our competitors’ activities and may therefore not deter litigation against us. The risks of being involved in such litigation may also increase as we become more visible as a public company and move into new markets and applications for our product candidates. There may also be patents and patent applications that are relevant to our technologies or product candidates that are unknown to us. For example, certain relevant patent applications may have been filed but not published. If such patents exist, or if a patent issues on any of such patent applications, that patent could be asserted against us. Third parties could bring claims against us that would cause us to incur substantial expenses and, if the claims against us are successful, could cause us to pay substantial damages, including treble damages and attorneys’ fees for willful infringement. The defense of such a suit could also divert the attention of our management and technical personnel. Further, if an intellectual property infringement suit were brought against us, we could be forced to stop or delay research, development or sales of the product that is the subject of the suit.

As a result of infringement claims, or to avoid potential claims, we may choose or be compelled to seek intellectual property licenses from third parties. These licenses may not be available on acceptable terms, or at all. Even if we are able to obtain a license, the license would likely obligate us to pay license fees or royalties or both, and the rights granted to us likely would be nonexclusive, which would mean that our competitors also could obtain licenses to the same intellectual property. Ultimately, we could be prevented

from commercializing a product candidate and/or technology or be forced to cease some aspect of our business operations if, as a result of actual or threatened infringement claims, we are unable to enter into licenses of the relevant intellectual property on acceptable terms. Further, if we attempt to modify a product candidate and/or technology or to develop alternative methods or products in response to infringement claims or to avoid potential claims, we could incur substantial costs, encounter delays in product introductions or interruptions in sales.

We may become involved in other lawsuits to protect or enforce our patents or other intellectual property, which could be expensive and time-consuming, and an unfavorable outcome could harm our business.

In addition to the possibility of litigation relating to infringement claims asserted against us, we may become a party to other patent litigation and other proceedings, including inter partes review proceedings, post-grant review proceedings, derivation proceedings declared by the USPTO and similar proceedings in foreign countries, regarding intellectual property rights with respect to our current or future technologies or product candidates or products. The cost to us of any patent litigation or other proceeding, even if resolved in our favor, could be substantial. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their substantially greater financial resources. Patent litigation and other proceedings may also absorb significant management time. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could impair our ability to compete in the marketplace.

Competitors may infringe or otherwise violate our intellectual property, including patents that may issue to or be licensed by us. As a result, we may be required to file claims in an effort to stop third-party infringement or unauthorized use. Any such claims could provoke these parties to assert counterclaims against us, including claims alleging that we infringe their patents or other intellectual property rights. This can be expensive, particularly for a company of our size, and time-consuming, and even if we are successful, any award of monetary damages or other remedy we may receive may not be commercially valuable. In addition, in an infringement proceeding, a court may decide that our asserted intellectual property is not valid or is unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that our intellectual property does not cover its technology. An adverse determination in any litigation or defense proceedings could put our intellectual property at risk of being invalidated or interpreted narrowly and could put our patent applications at risk of not issuing.

If the breadth or strength of our patent or other intellectual property rights is compromised or threatened, it could allow third parties to commercialize our technology or products or result in our inability to commercialize our technology and products without infringing third-party intellectual property rights. Further, third parties may be dissuaded from collaborating with us.

Interference or derivation proceedings brought by the USPTO or its foreign counterparts may be necessary to determine the priority of inventions with respect to our patent applications, and we may also become involved in other proceedings, such as re-examination proceedings, before the USPTO or its foreign counterparts. Due to the substantial competition in the pharmaceutical space, the number of such proceedings may increase. This could delay the prosecution of our pending patent applications or impact the validity and enforceability of any future patents that we may obtain. In addition, any such litigation, submission or proceeding may be resolved adversely to us and, even if successful, may result in substantial costs and distraction to our management.

Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. Moreover, intellectual property law relating to the fields in which we operate is still evolving and, consequently, patent and other intellectual property positions in our industry are subject to change and are often uncertain. We may not prevail in any of these suits or other efforts to protect our technology, and the damages or other remedies awarded, if any, may not be commercially valuable. During the course of this type of litigation, there could be public announcements of the results of hearings, motions or other interim proceedings or developments. If securities analysts or investors perceive these results to be negative, the market price for our common stock could be significantly harmed.

We may not be able to protect, or fully exploit, our intellectual property rights throughout the world, which could impair our competitive position.

Filing, prosecuting, defending and enforcing patents on all of our technologies, product candidates and products throughout the world would be prohibitively expensive. As a result, we seek to protect our proprietary position by filing patent applications in the United States and in select foreign jurisdictions and cannot guarantee that we will obtain the patent protection necessary to protect our competitive position in all major markets. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export infringing products to territories where we may obtain patent protection but where enforcement is not as strong as that in the United States. These products may compete with our current and future products in jurisdictions where we do not have any issued patents, and our patent claims or other intellectual property rights may not be effective or sufficient to prevent them from so competing.

Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents and other intellectual property protection, which could make it difficult for us to stop the infringement of our patents or the marketing of competing products in violation of our proprietary rights generally. The legal systems of certain countries make it difficult or

impossible to obtain patent protection for pharmaceutical products and services. Proceedings to enforce our patent rights in foreign jurisdictions could result in substantial costs and could divert our efforts and attention from other aspects of our business.

Even if we do secure patents in foreign jurisdictions, the legal systems in certain of those countries might require us, as examples, to do business through an entity that is partially owned by a local investor, or to grant license rights to local partners in a manner not required by the jurisdictions in which we currently operate. Requirements such as the foregoing could limit our ability to fully exploit and in the future monetize our product candidates and patents, as well as placing potential additional difficulties on our enforcement efforts in those jurisdictions.

If we are unable to protect the confidentiality of our trade secrets, our business and competitive position could be harmed.

In addition to seeking patents for some of our technologies and product candidates, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. We seek to protect these trade secrets, in part, by entering into non-disclosure and confidentiality agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, contract manufacturers, consultants, advisors and other third parties. We also enter into confidentiality and invention assignment agreements with our employees and consultants that obligate them to assign to us any inventions developed in the course of their work for us. However, we cannot guarantee that we have executed these agreements with each party that may have or have had access to our trade secrets or that the agreements we have executed will provide adequate protection. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. As a result, we may be forced to bring claims against third parties, or defend claims that they bring against us, to determine ownership of what we regard as our intellectual property. Monitoring unauthorized disclosure is difficult and we do not know whether the procedures we have followed to prevent such disclosure ~~are,~~have been or will be adequate. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States may be less willing or unwilling to protect trade secrets. If any of the technology or information that we protect as trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to, or independently developed by, a competitor, our competitive position would be harmed.

If our trademarks and trade names are not adequately protected, we may not be able to build name recognition in our markets of interest, and our business may be harmed.

Our trademarks or trade names may be challenged, infringed, circumvented, declared generic or determined to be infringing on other marks. As a means to enforce our trademark rights and prevent infringement, we may be required to file trademark claims against third parties or initiate trademark opposition proceedings. This can be expensive and time-consuming, particularly for a company of our size. In addition, in an infringement proceeding, a court may decide that a trademark of ours is not valid or is unenforceable, or may refuse to stop the other party from using the trademark at issue. We may not be able to protect our rights to these and other trademarks and trade names which we need to build name recognition by potential partners or customers in our markets of interest. We do not currently have any registered trademarks in the United States. Any trademark applications in the United States and in other foreign jurisdictions where we may file may not be allowed or may subsequently be opposed. In addition, other companies in the biopharmaceutical space may be using trademarks that are similar to ours and may in the future allege that our use of the trademark infringes or otherwise violates their trademarks. Over the long term, if we are unable to establish name recognition based on our trademarks and trade names, then we may not be able to compete effectively and our business may be harmed.

Third parties may assert ownership or commercial rights to inventions we develop.

Third parties may in the future make claims challenging the inventorship or ownership of our intellectual property. We have written agreements with collaborators that provide for the ownership of intellectual property arising from our collaborations. In some instances, there may not be adequate written provisions to address clearly the resolution of intellectual property rights that may arise from a collaboration. If we cannot successfully negotiate sufficient ownership and commercial rights to the inventions that result from our collaborations, or if disputes otherwise arise with respect to the intellectual property developed in the course of a collaboration, we may be limited in our ability to capitalize on the market potential of these inventions.

In addition, we may face claims by third parties that our agreements with employees, contractors or consultants obligating them to assign intellectual property to us are ineffective or are in conflict with prior or competing contractual obligations of assignment, which could result in ownership disputes regarding intellectual property we have developed or will develop and interfere with our ability to capture the commercial value of such inventions. Litigation may be necessary to resolve an ownership dispute, and if we are not successful, we may be precluded from using certain intellectual property, or may lose our exclusive rights in that intellectual property. Either outcome could have an adverse impact on our business.

Risks Related to Regulatory Approval of Our Product Candidates and Other Legal Compliance Matters

Even if we complete the necessary preclinical studies and clinical trials, the marketing approval process is expensive, time-consuming and uncertain and may prevent us from obtaining approvals for the commercialization of some or all of our product candidates. If we or our collaborators are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we

will not be able to commercialize, or will be delayed in commercializing, our product candidates, and our ability to generate revenue will be impaired.

Our product candidates and the activities associated with their development and commercialization, including their design, testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale and distribution, are subject to comprehensive regulation by the FDA and other regulatory agencies in the United States and by comparable authorities in other countries. Failure to obtain marketing approval for a product candidate will prevent us from commercializing the product candidate. We have not received approval to market any of our product candidates from regulatory authorities in any jurisdiction. We have only limited experience in filing and supporting the applications necessary to gain marketing approvals and expect to rely on third-party contract research organizations to assist us in this process. Securing regulatory approval requires the submission of extensive preclinical and clinical data and supporting information to the various regulatory authorities for each therapeutic indication to establish the product candidate’s safety and efficacy. Securing regulatory approval also requires the submission of information about the product manufacturing process to, and inspection of manufacturing facilities by, the relevant regulatory authority. Our product candidates may not be effective, may be only moderately effective or may prove to have undesirable or unintended side effects, toxicities or other characteristics that may preclude our obtaining marketing approval or prevent or limit commercial use.

The process of obtaining marketing approvals, both in the United States and elsewhere, is expensive, may take many years and can vary substantially based upon a variety of factors, including the type, complexity and novelty of the product candidates involved. We cannot assure you that we will ever obtain any marketing approvals in any jurisdiction. Changes in marketing approval policies during the development period, changes in or the enactment of additional statutes or regulations or changes in regulatory review for each submitted product application may cause delays in the approval or rejection of an application. The FDA and comparable authorities in other countries have substantial discretion in the approval process and may refuse to accept any application or may decide that our data is insufficient for approval and require additional preclinical or other studies, and clinical trials. In addition, varying interpretations of the data obtained from preclinical testing and clinical trials could delay, limit or prevent marketing approval of a product candidate. Additionally, any marketing approval we ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved product not commercially viable.

Any product candidate for which we obtain marketing approval could be subject to marketing restrictions or withdrawal from the market, and we may be subject to penalties if we fail to comply with regulatory requirements or if we experience unanticipated problems with our products.

Any product candidate for which we obtain marketing approval, along with the manufacturing processes, post-approval clinical data, labeling, advertising and promotional activities for such product, will be subject to continual requirements of and review by the FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, registration and listing requirements, cGMP requirements, quality assurance and corresponding maintenance of records and documents and requirements regarding the distribution of samples to health care professionals and recordkeeping. Even if marketing approval of a product candidate is granted, the approval may be subject to limitations on the indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for costly post-marketing testing and surveillance to monitor the safety or efficacy of the medicine. The FDA closely regulates the post approval marketing and promotion of drugs to ensure that they are marketed only for the approved indications and in accordance with the provisions of the approved labeling. The FDA imposes stringent restrictions on manufacturers’ communications regarding off-label use and if we do not market our products for their approved indications, we may be subject to enforcement action for off-label marketing. Physicians, on the other hand, may prescribe products for off-label uses. Although the FDA and other regulatory agencies do not regulate a physician’s choice of drug treatment made in the physician’s independent medical judgment, they do restrict promotional communications from companies or their sales force with respect to off-label uses of products for which marketing clearance has not been issued. Companies may only share truthful and not misleading information that is otherwise consistent with a product’s FDA approved labeling.

In addition, later discovery of previously unknown problems with our products, manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may result in, among other things:

Our relationships with healthcare providers, customers and third-party payors will be subject to applicable anti-kickback, fraud and abuse and other healthcare laws and regulations, which could expose us to criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, ~~physicians~~customers and third-party payors play a primary role in the recommendation and prescription of any product candidates for which we obtain marketing approval. Our current and future arrangements with third-party payors and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which we research, as well as market, sell and distribute our medicines for which we obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include the following:

Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, possible exclusion from government funded healthcare programs, such as Medicare and Medicaid, disgorgement, imprisonment, integrity oversight and reporting obligations to resolve allegations of non-compliance with these laws, and the curtailment or restructuring of our operations. If any of the health care professionals or other providers or entities with whom we expect to do business are found to be not in compliance with applicable laws, they may be subject to significant criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs.

Recently enacted and future legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our product candidates and affect the prices we may obtain.*

In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict or regulate post-approval activities and affect our ability to profitably sell any product candidates for which we obtain marketing approval.

The Medicare Prescription Drug, Improvement, and Modernization Act of 2003, or the Medicare Modernization Act, changed the way Medicare covers and pays for pharmaceutical products. The legislation expanded Medicare coverage for drug purchases by the elderly and introduced a new reimbursement methodology based on average sales prices for physician-administered drugs. In addition, this legislation provided authority for limiting the number of drugs that will be covered in any therapeutic class. Cost reduction initiatives and other provisions of this legislation could decrease the coverage and price that we receive for any approved products. While the Medicare Modernization Act applies only to drug benefits for Medicare beneficiaries, private payors often follow Medicare coverage policy and payment limitations in setting their own reimbursement rates. Therefore, any reduction in reimbursement that results from the Medicare Modernization Act may result in a similar reduction in payments from private payors.

Additionally, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, or collectively the PPACA, enacted in 2010, made a number of substantial changes in the way healthcare is financed by both governmental and private insurers. There continue to be significant developments in ~~and continued legislative activity around,~~ attempts to repeal ~~or repeal and replace~~ the PPACA. Due to these efforts, there is significant uncertainty regarding the future of the PPACA.

~~Since January 2017, President Trump has signed Executive Orders designed~~There have been executive, judicial, and Congressional challenges to ~~delay the implementation of any~~ certain ~~provisions~~aspects of the ~~PPACA or otherwise circumvent some of the requirements for health insurance mandated by the ACA.~~PPACA. For example, the 2020 federal spending package permanently eliminated, effective January 1, 2020, the PPACA-mandated “Cadillac” tax on high-cost employer-sponsored health coverage and medical device tax and, effective January 1, 2021, also ~~eliminates~~eliminated the health insurer tax. In addition, the Centers for Medicare & Medicaid Services issued a final rule, effective for plan year 2020 that gives states greater flexibility in setting benchmarks for insurers in the individual and small group marketplaces, which may have the effect of relaxing the essential health benefits required under the PPACA for plans sold through such marketplaces. The Trump administration has also announced that it will discontinue the payment of cost-sharing reduction, or CSR, payments to insurance companies until Congress approves the appropriation of funds for the CSR payments. The loss of the CSR payments is expected to increase premiums on certain policies issued by qualified health plans under the PPACA. A bipartisan bill to appropriate funds for CSR payments has been introduced in the Senate, but the future of that bill is uncertain. Further, each chamber of Congress has put forth multiple bills designed to repeal or repeal and replace portions of the PPACA. While Congress has not passed comprehensive repeal legislation, several bills affecting the implementation of certain taxes under PPACA have been signed into law. The Tax Act included a provision which repealed, effective January 1, 2019, the tax-based shared responsibility payment imposed by PPACA on certain individuals who fail to maintain qualifying health coverage for all or part of a year that is commonly referred to as the “individual mandate”. On December 14, 2018, a Texas U.S. District Court Judge ruled that the PPACA is unconstitutional in its entirety because the “individual mandate” was repealed by Congress as part of the Tax Act. Additionally, on December 18, 2019, the U.S. Court of Appeals for the 5th Circuit upheld the District Court ruling that the individual mandate was unconstitutional and remanded the case back to the District Court to determine whether the remaining provisions of the PPACA are invalid as well. ~~On March 2, 2020, the United States~~The U.S. Supreme Court ~~granted~~is currently reviewing the ~~petitions~~case, although it is unknown when a decision will be made. On February 10, 2021, the Biden administration withdrew the federal government’s support for ~~writs~~overturning the PPACA. Further, although the U.S. Supreme Court has not yet ruled on the constitutionality of ~~certiorari~~the PPACA, on January 28, 2021, President Biden issued an executive order to initiate a special enrollment period for purposes of obtaining health insurance coverage through the PPACA marketplace, which began on February 15, 2021 and will remain open through August 15, 2021. The executive order also instructs certain governmental agencies to review ~~this case,~~ and ~~has allotted one hour for oral arguments, which are expected~~reconsider their existing policies and rules that limit access to ~~occur in~~healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the ~~fall.~~PPACA. It is unclear how the Supreme Court ruling, other such litigation, and ~~other efforts to repeal and replace~~ the ~~PPACA~~healthcare reform measures of the Biden administration will impact the PPACA. We continue to evaluate the potential impact of PPACA and its possible repeal or replacement on our business.

Policy changes, including potential modification or repeal of all or parts of the PPACA or the implementation of new health care legislation could result in significant changes to the health care system, which may prevent us from being able to generate revenue, attain profitability or commercialize our drugs. We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand or lower pricing for our product candidates, or additional pricing pressures.

Further, there has been heightened governmental scrutiny of pharmaceutical pricing practices in light of the rising cost of prescription drugs and biologics. Such scrutiny has resulted in several recent congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. At the federal level, the Trump administration used several means to propose or implement drug pricing reform, including through federal budget proposals, executive orders and policy initiatives. For example, ~~the Trump administration’s budget proposal for fiscal year 2021 includes a $135 billion allowance to support legislative proposals seeking to reduce drug prices, increase competition, lower out-of-pocket drug costs for patients,~~on July 24, 2020 and ~~increase patient access to lower-cost generic and biosimilar drugs.~~ ~~On March 10,~~September 13, 2020, the Trump administration ~~sent “principles” for~~announced several executive orders related to prescription drug pricing that seek to ~~Congress, calling~~implement several of the administration’s proposals. As a result, the FDA released a final rule on September 24, 2020, effective November 30, 2020, providing guidance for ~~legislation that would, among other things, cap~~states to build and submit importation plans for drugs from Canada. Further, on November 20, 2020, HHS finalized a regulation removing safe harbor protection for price reductions from pharmaceutical manufacturers to plan sponsors under Medicare Part D, ~~beneficiary out-of-pocket~~either directly or through pharmacy ~~expenses, provide~~benefit managers, unless the price reduction is required by law. The implementation of the rule has been delayed by the Biden administration from January 1, 2022 to January 1, 2023 in response to ongoing litigation. The rule also creates a new safe harbor for price reductions reflected at the point-of-sale, as well as a new safe harbor for certain fixed fee arrangements between pharmacy benefit managers and manufacturers, the implementation of which have also been delayed until January 1, 2023. On November 20, 2020, CMS issued an ~~option to cap~~interim final rule implementing the Trump administration’s Most Favored Nation executive order, which would tie Medicare Part ~~D beneficiary monthly out-of-pocket expenses, and place limits on pharmaceutical~~B payments for certain physician-administered drugs to the lowest price ~~increases. Further,~~paid in other economically advanced countries, effective January 1, 2021. On December 28, 2020, the ~~Trump~~U.S. District Court in Northern California issued a nationwide preliminary injunction against implementation of the interim final rule. It is unclear whether the Biden administration ~~previously released a “Blueprint”~~will work to lower drug prices and reduce out of pocket costs of drugs that contains additional proposals to increase drug manufacturer competition, increase the negotiating power of certain federal healthcare programs, incentivize manufacturers to lower the list price of their products, and reduce the out of pocket costs of drug products paid by consumers. The Department of Health and Human Services has solicited feedback on some ofreverse these measures ~~and has implemented others under its existing authority. Congress and the Trump administration have each indicated that it will continue to seek new legislative and/~~or ~~administrative measures to control drug costs.~~pursue similar policy initiatives. In addition, there have been and continue to be similar initiatives at the state level to reduce drug costs.

In addition, other legislative changes have been proposed and ~~Economic Security~~adopted since the PPACA was enacted. On August 2, 2011, the Budget Control Act ~~or CARES Act, which~~of 2011 was signed into law, which includes reductions to Medicare payments to providers of 2% per fiscal year, which went into effect on April 1, 2013 and, due to subsequent legislative amendments to the statute will remain in ~~March 2020 and~~effect through 2030 unless additional Congressional action is ~~designed to provide financial support and resources to individuals and businesses affected by the~~taken. However, COVID-19 ~~pandemic,~~relief legislation suspended the 2% Medicare ~~payment reduction~~ sequester from May 1, 2020 through December 31, ~~2020, and extended the sequester by one year, through 2030.~~2021. It is possible that additional governmental action will be taken in response to ~~address~~ the COVID-19 pandemic. We expect that healthcare reform measures ~~that~~ may be adopted in the future, particularly in light of the new presidential administration, which could have a material adverse effect on our industry generally and on our ability to maintain or increase sales of any of our product candidates that we successfully commercialize.

Legislative and regulatory proposals have been made to expand post-approval requirements and restrict sales and promotional activities for pharmaceutical products. We cannot be sure whether additional legislative changes will be enacted, or whether the FDA regulations, guidance or interpretations will be changed, or what the impact of such changes on the marketing approvals of our product candidates, if any, may be. In addition, increased scrutiny by the U.S. Congress of the FDA’s approval process may significantly delay or prevent marketing approval, as well as subject us to more stringent product labeling and post-marketing testing and other requirements.

Our future success depends on our ability to retain our senior management team and to attract, retain and motivate qualified personnel.

We are highly dependent upon our senior management team, as well as the other principal members of our research and development teams. All of our executive officers are employed “at will,” meaning we or they may terminate the employment relationship at any time. We do not maintain “key person” insurance for any of our executives or other employees. The loss of the services of any of these persons could impede the achievement of our research, development and commercialization objectives.

Recruiting and retaining qualified scientific, clinical, manufacturing and sales and marketing personnel will also be critical to our success. We may not be able to attract and retain these personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us.

We ~~expect~~may need to expand our operations, and may encounter difficulties in managing our growth, which could disrupt our business.

~~We expect~~In the future, we may need to expand the scope of our operations, particularly in the areas of drug development, regulatory affairs and sales and marketing. To manage our ~~anticipated~~ future growth, we ~~must continue~~may need to implement and improve our managerial, operational and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. We may not be able to effectively manage ~~the expected~~an expansion of our operations or recruit and train additional qualified personnel. Moreover, ~~the expected~~an expansion of our operations may lead to significant costs and may divert our management and business development resources. For example, our facilities expenses may increase, or decrease which will vary depending on the time and terms of any facility lease or sublease we may enter into from time to time. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

We may engage in acquisitions that could disrupt our business, cause dilution to our stockholders or reduce our financial resources.

In the future, we may enter into transactions to acquire other businesses, products or technologies. Because we have not made any acquisitions to date, our ability to do so successfully is unproven. If we do identify suitable candidates, we may not be able to make such acquisitions on favorable terms, or at all. Any acquisitions we make may fail to strengthen our competitive position, and these transactions may be viewed negatively by customers or investors. We may decide to incur debt in connection with an acquisition or issue our common stock or other equity securities to the stockholders of the acquired company, which would reduce the percentage ownership of our existing stockholders. We could incur losses resulting from undiscovered liabilities of the acquired business that are not covered by the indemnification we may obtain from the seller. In addition, we may not be able to successfully integrate the acquired personnel, technologies and operations into our existing business in an effective, timely and non-disruptive manner. Acquisitions may also divert management attention from day-to-day responsibilities, increase our expenses and reduce our cash available for operations and other uses. We cannot predict the number, timing or size of future acquisitions or the effect that any such transactions might have on our operating results.

International expansion of our business exposes us to business, regulatory, political, operational, financial and economic risks associated with doing business in various jurisdictions globally.

Our business strategy incorporates international expansion, including establishing and maintaining relationships with service providers, distributors and manufacturers globally. Doing business internationally involves a number of risks, including:

The UK’s withdrawal from the EU, commonly referred to as Brexit, may have a negative effect on global economic conditions, financial markets and our business.

Following the result of a referendum in 2016, the United Kingdom left the European Union on January 31, 2020, commonly referred to as Brexit. Pursuant to the formal withdrawal arrangements agreed between the United Kingdom and the European Union, the United Kingdom will be subject to the Transition Period until December 31, 2020 during which European Union rules will continue to apply. Negotiations between the United Kingdom and the European Union are expected to continue in relation to the customs and trading relationship between the United Kingdom and the European Union following the expiry of the Transition Period.

The lack of clarity over which EU laws and regulations will continue to be implemented in the United Kingdom after the Transition Period (including financial laws and regulations, tax and free trade agreements, intellectual property rights, data protection laws, supply chain logistics, environmental, health and safety laws and regulations, immigration laws and employment laws) may negatively impact foreign direct investment in the United Kingdom, increase costs, depress economic activity and restrict access to capital. The uncertainty concerning the United Kingdom’s legal, political and economic relationship with the European Union after the Transition Period may be a source of instability in the international markets, create significant currency fluctuations, and/or otherwise adversely affect trading agreements or similar cross-border co-operation arrangements (whether economic, tax, fiscal, legal, regulatory or otherwise).

These developments, or the perception that any of them could occur, have had, and may continue to have, a significant adverse effect on global economic conditions and the stability of global financial markets, and could significantly reduce global market liquidity and limit the ability of key market participants to operate in certain financial markets. In particular, it could also lead to a period of considerable uncertainty in relation to the United Kingdom’s financial and banking markets, as well as on the regulatory process in Europe. Asset valuations, currency exchange rates and credit ratings may also be subject to increased market volatility.

If the United Kingdom and the European Union are unable to negotiate acceptable withdrawal terms or if other EU Member States pursue withdrawal, barrier-free access between the United Kingdom and other EU Member States or among the European Economic Area, or EEA, overall could be diminished or eliminated. The long-term effects of Brexit will depend on any agreements ~~(or~~

(or lack thereof) between the United Kingdom and the European Union and, in particular, any arrangements for the United Kingdom to retain access to EU markets after the Transition Period.

Such a withdrawal from the European Union is unprecedented, and it is unclear how the United Kingdom’s access to the European single market for goods, capital, services and labor within the European Union, or single market, and the wider commercial, legal and regulatory environment, will impact us.

The trading price of our common stock is likely to be volatile, and purchasers of our common stock could incur substantial losses.*

Our stock price has fluctuated in the past and is likely to be volatile in the future. The stock market in general and the market for biotechnology companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, investors may experience losses on their investment in our common stock. The market price for our common stock may be influenced by many factors, including:

In addition, in the past, stockholders have initiated class action lawsuits against companies following periods of volatility in the market prices of these companies’ stock. Such litigation, if instituted against us, could cause us to incur substantial costs and divert management’s attention and resources.

Concentration of ownership of our common stock among our existing executive officers, directors and principal stockholders may prevent new investors from influencing significant corporate decisions.

Our executive officers, directors and current beneficial owners of 5% or more of our common stock, in the aggregate, beneficially own a significant percentage of our outstanding common stock. These persons, acting together, will be able to significantly influence all matters requiring stockholder approval, including the election and removal of directors and any merger or

other significant corporate transactions. The interests of this group of stockholders may not coincide with the interests of other stockholders.

If securities or industry analysts do not publish research, or publish unfavorable research, about our business, our stock price and trading volume could decline.

The trading market for our common stock will depend in part on the research and reports that securities or industry analysts publish about us or our business, our market and our competitors. We do not have any control over these analysts. If one or more of the analysts who cover us downgrade our shares or change their opinion of our shares, our share price would likely decline. If one or more of these analysts cease coverage of our company or fail to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.

We have and will incur costs and demands upon management as a result of complying with the laws and regulations affecting public companies in the United States, which may harm our operating results.

As a public company listed in the United States, we have and will continue to incur significant additional legal, accounting and other expenses. In addition, changing laws, regulations and standards relating to corporate governance and public disclosure, including regulations implemented by the Securities and Exchange Commission, or SEC, and the Nasdaq Global Select Market, may increase legal and financial compliance costs and make some activities more time-consuming. These laws, regulations and standards are subject to varying interpretations, and as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. We intend to invest resources to comply with evolving laws, regulations and standards, and this investment may result in increased general and administrative expenses and a diversion of management’s time and attention from revenue-generating activities to compliance activities. If, notwithstanding our efforts to comply with new laws, regulations and standards, we fail to comply, regulatory authorities may initiate legal proceedings against us, and our business may be harmed.

Further, failure to comply with these laws, regulations and standards might also make it more difficult for us to obtain certain types of insurance, including director and officer liability insurance, and we might be forced to accept reduced policy limits and coverage or incur substantially higher costs to obtain the same or similar coverage. The impact of these events could also make it more difficult for us to attract and retain qualified persons to serve on our Board of Directors, on committees of our Board of Directors or as members of senior management.

We do not anticipate paying any cash dividends on our common stock so any returns will be limited to changes in the value of our common stock.

We have never declared or paid cash dividends on our common stock. We currently intend to retain our future earnings, if any, to fund the development and growth of our business. In addition, the terms of any existing or future credit facility may restrict our ability to pay dividends. Any return to stockholders will therefore be limited to the increase, if any, of our stock price.

If we are unable to maintain proper and effective internal controls over financial reporting, the accuracy and timeliness of our financial reporting and the market price of our common stock may be adversely affected.

Effective internal controls are necessary for us to provide reliable financial reports and to protect from fraudulent, illegal or unauthorized transactions. If we cannot provide effective controls and reliable financial reports, our business and operating results could be harmed. We have in the past discovered, and may in the future discover, areas of our internal controls that need improvement. We are required, pursuant to Section 404 of the Sarbanes-Oxley Act, to furnish a report by management on the effectiveness of our internal control over financial reporting. ~~Our~~In the future, our independent registered public accounting firm may also ~~needs~~need to attest to the effectiveness of our internal control over financial reporting.

If material weaknesses or control deficiencies occur in the future, we are unable to comply with the requirements of Section 404 in a timely manner, we are unable to assert that our internal control over financial reporting is effective, or if our independent registered public accounting firm is unable to express an opinion as to the effectiveness of our internal control over financial reporting, we may be unable to report our financial results accurately on a timely basis, which could cause our reported financial results to be materially misstated and result in the loss of investor confidence and cause the market price of our common stock to decline.

Provisions in our corporate charter documents and under Delaware law may prevent or frustrate attempts by our stockholders to change our management or hinder efforts to acquire a controlling interest in us, and the market price of our common stock may be lower as a result.

There are provisions in our certificate of incorporation and bylaws that may make it difficult for a third party to acquire, or attempt to acquire, control of our company, even if a change in control was considered favorable by our stockholders.

Our charter documents also contain other provisions that could have an anti-takeover effect, such as:

Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law, which prohibit a person who owns 15% or more of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner. Any provision in our certificate of incorporation or our bylaws or Delaware law that has the effect of delaying or deterring a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our common stock, and could also affect the price that some investors are willing to pay for our common stock.

Our amended and restated certificate of incorporation ~~provides that~~designates the Court of Chancery of the State of Delaware isand our amended and restated bylaws designate the federal district courts of the United States of America as the exclusive ~~forum~~forums for substantially all disputes between us and our stockholders, which ~~could limit~~will restrict our ~~stockholders’~~stockholders' ability to ~~obtain a favorable~~choose the judicial forum for disputes with us or our directors, officers, or employees.

Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware is the exclusive forum for any derivative action or proceeding brought on our behalf; any action asserting a breach of fiduciary duty; any action asserting a claim against us arising pursuant to the Delaware General Corporation Law, our amended and restated certificate of incorporation or our bylaws; or any action asserting a claim against us that is governed by the internal affairs ~~doctrine.~~ doctrine.

The provisions would not apply to suits brought to enforce a duty or liability created by the Exchange Act or any other claim for which the U.S. federal courts have exclusive jurisdiction. Furthermore, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all such Securities Act actions. Accordingly, both state and federal courts have jurisdiction to entertain such claims. Our stockholders cannot waive compliance with the federal securities laws and the rules and regulations thereunder. To prevent having to litigate claims in multiple jurisdictions and the threat of inconsistent or contrary rulings by different courts, among other considerations, our amended and restated bylaws provide that, unless we consent in writing to the selection of an alternative forum, the federal district courts of the United States of America will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act. While the Delaware courts have determined that such choice of forum ~~provision~~provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions. In such instance, we would expect to vigorously assert the validity and enforceability of the exclusive forum provisions of our amended and restated certificate of incorporation. This may require significant additional costs associated with resolving such action in other jurisdictions and there can be no assurance that the provisions will be enforced by a court in those other jurisdictions.

These exclusive choice of forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees, which may discourage ~~such~~ lawsuits against us and our directors, officers, and other employees. Some companies that adopted a similar federal district court forum selection provision are currently subject to a suit in the Chancery Court of Delaware by stockholders who assert that the provision is not enforceable.If a court were to find ~~the choice of forum provision contained in our amended and restated certificate of incorporation~~such exclusive-forum provisions to be inapplicable or unenforceable in an action, we may incur further significant additional costs associated with resolving ~~such action~~the dispute in other jurisdictions, all of which could harm our ~~business and financial condition.~~business.

Incorporation By Reference
Exhibit
Number

Exhibit Description

Form

SEC File No.

Exhibit

Filing Date

    3.1

Amended and Restated Certificate of Incorporation of Calithera Biosciences, Inc.

8-K

001-36644

3.1

10/07/2014

    3.2

Amended and Restated Bylaws of Calithera Biosciences, Inc.

S-1

333-198355

3.4

9/19/2014

    4.1

Reference is made to Exhibits 3.1 through 3.2.








    4.2

Form of common stock certificate.

S-1

333-198355

4.1

9/25/2014

  31.1

Certification of Principal Executive and Financial Officer pursuant to Rule 13a-14(a).


  32.1*

Certification of Principal Executive and Financial Officer pursuant to Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended, and 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.








101.INS

XBRL Instance Document.








101.SCH**

XBRL Taxonomy Extension Schema Document.








101.CAL**

XBRL Taxonomy Extension Calculation Linkbase Document.

101.DEF**

XBRL Taxonomy Extension Definition Linkbase Document.








101.LAB**

XBRL Taxonomy Extension Label Linkbase Document.








101.PRE**

XBRL Taxonomy Extension Presentation Linkbase Document.

		Incorporation By Reference
Exhibit Number	Exhibit Description	Form	SEC File No.	Exhibit	Filing Date

3.1	Amended and Restated Certificate of Incorporation of Calithera Biosciences, Inc.	8-K	001-36644	3.1	10/7/2014

3.2	Amended and Restated Bylaws of Calithera Biosciences, Inc.	10-Q	001-36644	3.2	8/10/2020

4.1	Reference is made to Exhibits 3.1 through 3.2.

4.2	Form of common stock certificate.	S-1	333-198355	4.1	9/25/2014

10.1	Fourth Amendment to Lease Agreement between Are-Technology Center SSF, LLC and the Registrant, dated March 8, 2021.

31.1	Certification of Principal Executive Officer pursuant to Rule 13a-14(a).

31.2	Certification of Principal Financial and Accounting Officer pursuant to Rule 13a-14(a).

32.1*	Certification of Principal Executive Officer pursuant to Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended, and 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

32.2*	Certification of Principal Financial and Accounting Officer pursuant to Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended, and 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS**	Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCH**	Inline XBRL Taxonomy Extension Schema Document.

101.CAL**	Inline XBRL Taxonomy Extension Calculation Linkbase Document.

101.DEF**	Inline XBRL Taxonomy Extension Definition Linkbase Document.

101.LAB**	Inline XBRL Taxonomy Extension Label Linkbase Document.

101.PRE**	Inline XBRL Taxonomy Extension Presentation Linkbase Document.

104	The cover page from the Company’s Quarterly Report on Form 10-Q for the three months ended March 31, 2021, has been formatted in Inline XBRL.

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		Page
PART I. FINANCIAL INFORMATION		3

Item 1.	Financial Statements (Unaudited)	3

	Condensed Consolidated Balance Sheets at March 31, ~~2020,~~2021, and December 31, ~~2019~~2020	3
	Condensed Consolidated Statements of Operations for the Three Months Ended March 31, 2021 and 2020 ~~and 2019~~	4
	Condensed Consolidated Statements of Comprehensive Loss for the Three Months Ended March 31, ~~2020~~2021 and ~~2019~~2020	5
	Condensed Consolidated Statements of Stockholders’ Equity for the Three Months Ended March 31, ~~2020~~2021 and ~~2019~~2020	6
	Condensed Consolidated Statements of Cash Flows for the Three Months Ended March 31, ~~2020~~2021 and ~~2019~~2020	7
	Notes to Condensed Consolidated Financial Statements	8

Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	1819

Item 3.	Quantitative and Qualitative Disclosures About Market Risk	2324

Item 4.	Controls and Procedures	2324

PART II. OTHER INFORMATION		2425

Item 1.	Legal Proceedings	2425

Item 1A.	Risk Factors	2425

Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	5052

Item 3.	Defaults Upon Senior Securities	5052

Item 4.	Mine Safety Disclosures	5052

Item 5.	Other Information	5052

Item 6.	Exhibits	5153

SIGNATURES		5254

	Severance Costs Related to Reduction in Workforce
Accrued balance as of January 1, 2021	$	—
Charges		1,142
Cash payments		(936	)
Accrued balance as of March 31, 2021	$	206

	Calithera Biosciences, Inc.

Date: May ~~7, 2020~~6, 2021	By:	/s/ Susan M. Molineaux
		Susan M. Molineaux, Ph.D.
		President and Chief Executive Officer
		(Principal Executive ~~and Principal Financial~~ Officer)

Date: May ~~7, 2020~~6, 2021	By:	/s/ Stephanie Wong
		Stephanie Wong
		~~Senior Vice President, Finance~~Chief Financial Officer and Secretary
		(Principal Financial and Accounting Officer)

	Stock Awards (PSUs and RSUs)
	Shares			Weighted- Average Grant-Date Fair Value		Weighted- Average Remaining Contractual Term (Years)		Aggregate Value Intrinsic
Outstanding — December 31, 2020		—		$	—
PSUs and RSUs — Awarded		2,123			2.98
PSUs and RSUs — Cancelled		(75	)		—
Outstanding — March 31, 2021		2,048		$	2.98		1.02	$	4,957

Large accelerated filer

Accelerated filer

Non-accelerated filer

Smaller reporting company

Emerging ~~Growth Company~~growth company