As filed with the Securities and Exchange Commission on September 15, 2017August 10, 2023

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

MOLECULAR TEMPLATES, INC.

(Exact name of registrant as specified in its charter)

9301 Amberglen Blvd

Suite 100

Austin, TexasTX 78729

(512)869-1555

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Eric E. Poma, Ph.D.

Chief Executive Officer and Chief Scientific Officer

Molecular Templates, Inc.

9301 Amberglen Blvd, Suite 100

Austin, Texas 78729

(512)869-1555

(Name, address, including zip code, and telephone number, including, area code, of agent for service)

CopyWith copies to:

William C. Hicks, Esq.

Matthew J. Gardella, Esq.

Mintz, Levin, Cohn, Ferris, Glovsky &and Popeo, P.C.

One Financial Center

Boston, Massachusetts 02111

(617)542-6000

Approximate date of commencement of proposed sale to the public: public:

From time to time after the effective date of this Registration Statement.registration statement.

If the only securities being registered on this formForm are being offered pursuant to dividend or interest reinvestment plans, please check the following box.box:  ☐

If any of the securities being registered on this formForm are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.box:  ☒

If this formForm is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this formForm is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this formForm is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  ☐

If this formForm is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, or a smaller reporting company, or an emerging growth company. See definitionthe definitions of “large accelerated filer,” “accelerated filer” andfiler,” “smaller reporting company” and “emerging growth company” in Rule12b-2 of the Exchange Act. (Check one):

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)7(a)(2)(B) of the ExchangeSecurities Act.  ☐

CALCULATIONTHE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION FEE

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said SectionSTATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a), may determine.MAY DETERMINE.

The information in this prospectus is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission.changed without notice. The selling stockholders may not sell these securities until the registration statement filed with the Securities and Exchange Commission declares the registration statementis effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED SEPTEMBER 15, 2017AUGUST 10, 2023

PROSPECTUS

11,612,582

42,592,191 Shares of

Common Stock

Offered by the Selling Stockholders

The selling stockholders of Molecular Templates, Inc. (“Molecular,” “we,” “us” or the “Company”) listed beginning on page 9 ofidentified in this prospectus, including their pledgees, donees, transferees, assigns or other successors in interest (“selling stockholders”), may, from time to time, offer and resell under this prospectus (i) up to 8,716,05642,592,191 shares (“Shares”) of common stock, par value $0.001 per share, of the Company (the “Common Stock”), which consist of (i) 24,260,644 shares of our common stock and (ii) up to 2,896,526 shares of our common stock issuable upon exercise of warrants acquiredCommon Stock held by certain of the selling stockholders under the Financing Securities Purchase Agreement (defined below) (the “Warrants”). The selling stockholders acquired theand (ii) 18,331,547 shares of common stock andCommon Stock issuable upon the Warrants from us either:

We are registering the resale of thepurchase shares of common stock coveredCommon Stock held by this prospectus as required by the Registration Rights Agreement we entered into with the Investors on August 1, 2017. Thecertain selling stockholders will receive all of the proceeds from any sales of the shares offered hereby.stockholders. We will not receive any proceeds from the sale of the proceeds, but we will incur expenses in connection with the offering. To the extent the Warrants are exercised for cash, if at all, we will receiveShares offered by this prospectus, except the exercise price of $0.001 per share of the Warrants.Pre-Funded Warrants exercised for cash.

Our registration of the Shares covered by this prospectus does not mean that the selling stockholders will offer or sell any of the Shares. The selling stockholders may sell any, all or none of the Shares offered by this prospectus and we do not know when or in what amount the selling stockholders may sell their Shares hereunder following the effective date of this registration statement. The timing and amount of any sale are within the sole discretion of the selling stockholders.

The selling stockholders may sell these sharesthe Shares through public or private transactions at market prices prevailing at the time of sale or at negotiated prices. The timing and amount of any sale are within the sole discretion of the selling stockholders. Our registration of the shares of common stock covered by this prospectus does not mean that the selling stockholders will offer or sell any of the shares. For further information regarding the possible methods by which the sharesShares may be distributed, see “Plan of Distribution” beginning on page 13 of15 in this prospectus.

Our common stockCommon Stock is listed on The NASDAQNasdaq Capital Market under the symbol “MTEM.” The“MTEM”. On August 4, 2023, the last reported sale price offor our common stock on September 14, 2017Common Stock was $6.74$0.58 per share.

Investing in our common stock is highly speculative andCommon Stock involves a significanthigh degree of risk. Please consider carefully the specific factors set forthrisks described in this prospectus under “Risk Factors” beginning on page 36 of this prospectus and in our filings with the Securities and Exchange Commission.Commission.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracydetermined if this prospectus is truthful or adequacy of the disclosures in this prospectus.complete. Any representation to the contrary is a criminal offense.

The date of thisThis prospectus is dated                 , 20172023

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we have filed with the Securities and Exchange Commission (the “SEC”) pursuant to which the selling stockholders named herein may, from time to time, offer and sell or otherwise dispose of the shares of our common stockShares covered by this prospectus. You should not assume that the information contained in this prospectus is accurate on any date subsequent to the date set forth on the front cover of this prospectus or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus is delivered or shares of common stockShares are sold or otherwise disposed of on a later date.

This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the Shares, you should refer to the registration statement including the exhibits. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find More Information.” We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference in the accompanying prospectus were made solely for the benefit of the parties to such agreement, including in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs. It is important for you to read and consider all information contained in this prospectus, including the documents incorporated by reference therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you under “Where You Can Find AdditionalMore Information” and “Information Incorporated“Incorporation of Certain Documents by Reference” in this prospectus.

We and the selling stockholders have not authorized anyone to give any information or to make any representation to you other than those contained or incorporated by reference in this prospectus. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus. This prospectus does not constitute an offer to sell or the solicitation of an offer to buy any of our shares of common stockCommon Stock other than the shares of our common stockShares covered hereby, nor does this prospectus constitute an offer to sell or the solicitation of an offer to buy any securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. Persons who come into possession of this prospectus in jurisdictions outside the United States are required to inform themselves about, and to observe, any restrictions as to the offering and the distribution of this prospectus applicable to those jurisdictions.

Unless we have indicated otherwise, orThis prospectus, including the context otherwise requires, referencesdocuments incorporated by reference herein, include statements that are based on various assumptions and estimates that are subject to numerous known and unknown risks and uncertainties. Some of these risks and uncertainties are described in the section entitled “Risk Factors” beginning on page 6 of this prospectus and as described in Part II, Item 1A (Risk Factors) of our most recent Quarterly Report on Form 10-Q for the quarter ended June 30, 2023 filed with the SEC on August 10, 2023, as updated by our subsequent filings with the SEC under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These and other important factors could cause our future results to be materially different from the results expected as a result of, or implied by, these assumptions and estimates. You should read the information contained in, or incorporated by reference into, this prospectus completely and with the understanding that future results may be materially different from and worse than what we expect. See the information included under the heading “Special Note Regarding Forward-Looking Statements.”

In this prospectus, references to “Molecular,” “Molecular Templates,” the “Company,” “we,” “us”“us,” and “our” refer to Molecular Templates, Inc.

1

2

3

4

5

RISK FACTORS

An investmentInvesting in our common stockCommon Stock involves a high degree of risk. Prior to making a decision about investing in our common stock, youYou should carefully consider the risks and uncertainties and assumptionsall other information, documents or reports included or incorporated by reference in this prospectus and, if applicable, any prospectus supplement or other offering materials, including the risks and uncertainties discussed underand described in Part II, Item 1A “Risk Factors,” in(Risk Factors) of our Annualmost recent Quarterly Report onForm 10-K10-Q for the fiscal yearquarter ended December 31, 2016June 30, 2023 filed with the SEC on March 27, 2017 (as amended by Amendment No. 1 on Form10-K/A filed on April 28, 2017),August 10, 2023, as updated by our subsequent filings with the SEC under the Securities Exchange Act, of 1934, as amended (the “Exchange Act”), which are incorporated herein by reference, together with the information in this prospectus, and any other informationupdates to those risk factors included from time to time in our periodic and current reports filed with the SEC and incorporated by reference intoin this prospectus. See “Where You Can Find Additional Information” and “Information Incorporated by Reference.” Additional risks and uncertainties not presently knownprospectus, before making any decision to us or that we currently deem immaterial may also affectinvest in shares of our Common Stock. If any of the events discussed in these risk factors occurs, our business, prospects, results of operations, financial condition or resultsand cash flows could be materially harmed. If that were to happen, the trading price of operations. The occurrence of any of these known or unknown risks might causeour Common Stock could decline, and you tocould lose all or part of your investment ininvestment. Additional risks not currently known to us or other factors not perceived by us to present significant risks to our common stock.

6

THE MERGER

On August 1, 2017, we completed our business combination with Molecular Templates OpCo in accordance with the terms of the Merger Agreement. Pursuant to the Merger Agreement, we formed a wholly owned subsidiary that merged with and into Molecular Templates OpCo, with Molecular Templates OpCo surviving the Merger and becoming our wholly owned subsidiary. In connection with and prior to the consummation of the Merger, we effectedan 11-for-1 reverse stock split (the “Reverse Stock Split”) of the shares of our common stock. The Merger and the Reverse Stock Split were both approved by our stockholders at the annual meeting of stockholders held on July 31, 2017. Upon the consummation of the Merger, we changed our name from “Threshold Pharmaceuticals, Inc.” to “Molecular Templates, Inc.”

Immediately prior to and in connection with the Merger, each outstanding share of Molecular Templates OpCo preferred stock was converted into one share of Molecular Templates OpCo common stock at ratios determined in accordance with Molecular Templates OpCo’s certificate of incorporation then in effect. Under the terms of the Merger Agreement, at the effective time of the Merger, we issued shares of our common stock to Molecular Templates OpCo stockholders at an exchange ratio of 7.7844 shares of our common stock, after taking into account the Reverse Stock Split, in exchange for each share of Molecular Templates OpCo common stock outstanding immediately prior to the Merger. The exchange ratio was determined through arms’-length negotiations between us and Molecular Templates OpCo. An aggregate of approximately 11,656,475 shares of our common stock were issued to the Molecular Templates OpCo stockholders in the Merger. We also assumed all of the stock options issued and outstanding under Molecular Templates OpCo’s 2009 Stock Plan, as amended, and issued and outstanding warrants of Molecular Templates OpCo, with such stock options and warrants henceforth representing the right to purchase a number of shares of our common stock equal to 7.7844 multiplied by the number of shares of Molecular Templates OpCo common stock previously represented by such stock options and warrants, as applicable, after taking into account the Reverse Stock Split.

The issuance of the shares of our common stock to the former stockholders of Molecular Templates OpCo was registered with the SEC on a Registration Statementon Form S-4 (Reg. No. 333-217993).

The foregoing description of the Merger and the Merger Agreement is not complete and is subject to and qualified in its entirety by reference to the Merger Agreement, a copy of which is filed as an exhibit hereto and is incorporated herein by reference. The representations, warranties and covenants made by us in the Merger Agreement were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties thereto, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were made as of an earlier date. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

THE PRIVATE PLACEMENT AND THE TAKEDA FINANCING

On August 1, 2017, we entered into the Financing Securities Purchase Agreement with Longitude Venture Partners III, L.P. and certain other accredited investors, pursuant to which we sold an aggregate of 5,793,063 units (the “Units”) having an aggregate purchase price of $40.0 million, each such Unit consisting of (i) one (1) share (the “Shares”) of our common stock and (ii) a Warrant to purchase 0.50 shares of our common stock (the “Private Placement”). The Private Placement was pursuant to Equity Commitment Letter agreements entered into by and between us and each of the PIPE Investors in March and June 2017. The purchase price per Unit was $6.9048. The Warrants will be exercisable for a period of seven years from the date of their issuance ata per-share exercise price of $6.8423 (which exercise price shall be payable in cash or through a cashless exercise mechanic), subject to certain adjustments as specified in the Warrants.

In connection with the execution on June 23, 2017 of a collaboration and license agreement between Molecular Templates OpCo and Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda, on June 23, 2017, we and Molecular Templates OpCo entered into the Takeda Stock Purchase Agreement with Takeda, pursuant to which Takeda agreed to purchase shares of our common stock to occur following the consummation of the Merger and the Private Placement. Pursuant to the Takeda Stock Purchase Agreement, on August 1, 2017, following the consummation of the Merger and the Private Placement, we sold 2,922,993 shares of our common stock to Takeda (the “Takeda Shares”) at a price per share of $6.8423 (the “Takeda Financing”).

In connection with the Private Placement and the subsequent consummation of the Takeda Financing, we entered into a Registration Rights Agreement (the “Registration Rights Agreement”) with each Investor, pursuant to which we are obligated, among other things, to file a registration statement with the SEC within 45 days following the closing of the Private Placement and the Takeda Financing for purposes of registering the Shares and Takeda Shares and the shares of our common stock issuable upon exercise of the Warrants for resale by the PIPE Investors, (ii) use our commercially reasonable efforts to have the registration statement declared effective as soon as practicable after filing, and in any event no later than 120 days after the closing of the Private Placement and the Takeda Financing, and (iii) maintain the registration until all registrable securities may be sold pursuant to Rule 144 under the Securities Act of 1933, as amended (the “Securities Act”), without restriction as to volume. If the registration statement (i) is not filed with the SEC by the filing deadline, (ii) is not declared effective by the effectiveness deadline, (iii) in certain circumstances, ceases to be effective or the Investors are not permitted to use the prospectus to resell their shares, in each case, for more than 30 consecutive trading days or 60 trading days during any 12 month period, or (iv) is not effective and we fail to satisfy the current public information requirement pursuant to Rule 144(c)(1), we must pay liquidated damages equal to 1% of the aggregate purchase price paid by the Investor and, for each 30 day period thereafter, pay an additional 1%, subject to a maximum amount of 6% in the aggregate.

The foregoing description of the Registration Rights Agreement is not complete and is subject to and qualified in its entirety by reference to the Registration Rights Agreement, a copy of which is filed as an exhibit hereto and is incorporated herein by reference.

CAUTIONARYSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents we have filed with the SEC that are incorporated by reference herein contain forward-looking statements“forward-looking statements” within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act.Act that involve substantial risks and uncertainties. In some cases, forward-looking statements are identified by the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “future,” “goals,” “intend,” “likely,” “may,” “might,” “ongoing,” “objective,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “strategy,” “will” and “would” or the negative of these terms, or other comparable terminology intended to identify statements about the future. These statements relateinvolve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these forward-looking statements.

Although we believe that we have a reasonable basis for each forward-looking statement contained in this prospectus and the documents that we have filed with the SEC that are incorporated by reference, such statements are based on a combination of facts and factors currently known by us and our expectations of the future, about which we cannot be certain. Forward-looking statements include statements about:

7

Any forward-looking statements in this prospectus reflect our current views with respect to future events or to our future financial performance and involve known and unknown risks, uncertainties and other factors whichthat may cause our actual results, performance or achievements to be materially different from any future results, performancesperformance or achievements expressed or implied by thethese forward-looking statements. Forward-looking statementsFactors that may cause actual results to differ materially from current expectations include, but are not limited to, statements about:

In some cases, you can identify forward-looking statements by terms suchoperate; and market conditions. You should refer to the section titled “Risk Factors” of this prospectus and as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “project,” “should,” “target,” “will,” “would” or other words that convey uncertaintydescribed in Part II, Item 1A (Risk Factors) of future events or outcomes to identify these forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. We discuss many of these risks in greater detail in our reports filed from time to time under the Securities Act and/or the Exchange Act, including the risks identified in our Annualmost recent Quarterly Report onForm 10-K10-Q for the fiscal yearquarter ended December 31, 2016June 30, 2023 filed with the SEC on March 27, 2017 (as amended by Amendment No. 1 on Form10-K/A filed on April 28, 2017),August 10, 2023, as updated by our subsequent filings with the SEC under the Exchange Act. We encourage youAct, as updated by our subsequent filings with the SEC under the Exchange Act for further discussion of the important factors that may cause our actual results to readdiffer materially from those expressed or implied by our forward-looking statements. As a result of these filings as theyfactors, we cannot assure that the forward-looking statements in this prospectus the documents we have filed with the SEC that are made. Also,incorporated by reference will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, representthese statements should not be regarded as representations or warranties by us or any other person that we will achieve our estimatesobjectives and assumptions onlyplans in any specified time frame, or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of the document containing the applicable statement.this prospectus, and while

8

we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements as predictions of future events.

You should read this prospectus, the documents that we have incorporated by reference herein and any prospectus supplement or free writing prospectus thatthe documents we have authorized for use in connection with this offeringfiled as exhibits to the registration statement, completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of theour forward-looking statements in the foregoing documents by these cautionary statements.

9

USE OF PROCEEDS

We will not receive anyare filing the registration statement of which this prospectus forms a part to permit the holders of the proceeds from the saleShares of the common stock by the selling stockholders named in this prospectus. The selling stockholders will receive all of the proceeds from this offering.

Pursuant to conditions set forthour Common Stock described in the Warrants, the Warrantssection entitled “Selling Stockholders” to resell such Shares. We are exercisablenot selling any securities under certain circumstances on a cashless basis,this prospectus, and should a selling stockholder elect to exercise on a cashless basis we will not receive any proceeds from the sale or other disposition of common stock issued uponshares of our Common Stock held by the cashlessselling stockholders, except with respect to amounts received by us due to the exercise of the Warrant. Pre-Funded Warrants.

The holdersselling stockholders will pay any underwriting discounts and commissions and expenses incurred by the selling stockholders for brokerage, accounting, tax or legal services or any other expenses incurred by the selling stockholders in disposing of these Shares. We will bear all other costs, fees and expenses incurred in effecting the registration of the Warrants are not obligated to exercise their Warrants,Shares covered by this prospectus, including, without limitation, all registration and we cannot predict whether holdersfiling fees, Nasdaq listing fees and fees and expenses of the Warrants will choose to exercise all or any of their Warrants or if they will do so for cash or on a cashless basis. However, if all of the Warrants were exercised for cash, we would receive gross proceeds of approximately $19.8 million. We currently intend to use such proceeds, if any, for working capitalour counsel and general corporate purposes.

10

SELLING STOCKHOLDERS

This prospectus relatescovers the resale from time to the sale or other dispositiontime of up to 11,612,582 sharesan aggregate of 42,592,191 Shares of our common stock and shares of common stock issuable to the selling stockholders upon exercise of the WarrantsCommon Stock by the selling stockholders, named below, and their donees, pledgees, transferees or othersuccessors-in-interest sellingwhich consist of (i) 24,260,644 shares of common stock or interests in shares of common stock received after the date of this prospectus from a selling stockholder as a gift, pledge, partnership distribution or other transfer. The shares of common stock covered hereby were issuedCommon Stock held by us in the Private Placement and the Takeda Financing. See “The Private Placement and the Takeda Financing” beginning on page 5 of this prospectus.

The table below sets forth information as of the date of this prospectus, to our knowledge, for the selling stockholders and other information regarding(ii) 18,331,547 shares of Common Stock issuable upon the beneficial ownership (as determined under Section 13(d)exercise of Pre-Funded Warrants to purchase shares of Common Stock held by certain selling stockholders. The Shares registered for resale herein are pursuant to the Exchange ActSecurities Purchase Agreement between us and the rulesselling stockholders and regulations thereunder) of therelate to shares of common stock held by the selling stockholders. stockholders not otherwise previously registered for resale.

The secondselling stockholders identified in the table below may from time to time offer and sell under this prospectus any or all of the Shares described under the column lists“Number of Shares of Common Stock Being Offered” in the table below. The table below has been prepared based upon information furnished to us by the selling stockholders as of July 31, 2023. The selling stockholders identified below may have sold, transferred or otherwise disposed of some or all of their shares since the date on which the information in the following table is presented in transactions exempt from or not subject to the registration requirements of the Securities Act. Information concerning the selling stockholders may change from time to time and, if necessary, we will amend or supplement this prospectus accordingly and as required.

The following table and footnote disclosure following the table sets forth the name of each selling stockholder, the nature of any position, office or other material relationship, if any, that the selling stockholders have had within the past three years with us or with any of our predecessors or affiliates, and the number of shares of common stockour Common Stock beneficially owned by the selling stockholders as of August 15, 2017.before this offering. The third column lists the maximum number of shares described under the column “Shares of common stock that may be sold or otherwise disposedCommon Stock Beneficially Owned Before this Offering” for each selling stockholder includes all shares of our Common Stock beneficially held by such selling stockholder as of July 31, 2023, which includes (i) all shares of our Common Stock purchased by such selling stockholder in the Private Placement and (ii) all of the shares of Common Stock issuable upon exercise of the Pre-Funded Warrants purchased by such selling stockholders pursuantstockholder in the Private Placement, subject to the registration statementBeneficial Ownership Limitation. The number of which this prospectus forms a part. The selling stockholders may sell or otherwise dispose of some, all or none of their shares. Pursuant to Rules13d-3 and13d-5shares reflected are those beneficially owned, as determined under applicable rules of the Exchange Act,SEC, and the information is not necessarily indicative of beneficial ownership for any other purpose. Under applicable SEC rules, beneficial ownership includes any shares of our common stockCommon Stock as to which a stockholderperson has sole or shared voting power or investment power and also any shares of our common stockCommon Stock which the stockholderperson has the right to acquire within 60 days after July 31, 2023 through the exercise of August 15, 2017. The percentageany option, warrant or right or through the conversion of beneficial ownership forany convertible security. Unless otherwise indicated in the footnotes to the table below and subject to community property laws where applicable, we believe, based on information furnished to us that each of the selling stockholders is based on 26,880,857named in this table has sole voting and investment power with respect to the shares indicated as beneficially owned.

11

We have assumed that all shares of our common stock outstandingCommon Stock reflected in the table as of August 15, 2017 andbeing offered in the offering covered by this prospectus will be sold from time to time in this offering. We cannot provide an estimate as to the number of shares of our common stock issuable upon exercise or conversion of convertible securitiesCommon Stock that are currently exercisable or convertible or are exercisable or convertible within 60 days of August 15, 2017 beneficially owned by the applicable selling stockholder. Except as described below, to our knowledge, none of the selling stockholders has been an officer or director of ours or of our affiliates within the past three years or has any material relationship with us or our affiliates within the past three years. Our knowledge is based on information providedwill be held by the selling stockholders in connection withupon termination of the filing ofoffering covered by this prospectus as well as information obtained from relevant Schedule 13D and 13G filings.

The shares of common stock being covered hereby may be sold or otherwise disposed of from time to time during the period the registration statement of which this prospectus is a part remains effective, by or for the account of the selling stockholders. After the date of effectiveness of such registration statement,because the selling stockholders may have soldoffer some, all or transferred, in transactions covered by this prospectus or in transactions exempt from the registration requirements of the Securities Act, some or allnone of their common stock.

shares of Common Stock being offered in the offering. Information about the selling stockholders may change over time. Any changed information will be set forth in an amendment to the registration statement or supplement to this prospectus, to the extent required by law.

		Shares of Common Stock Beneficially Owned Before this Offering								Number of Shares of Common Stock Being Offered				Shares of Common Stock To Be Beneficially Owned Upon Completion of this Offering
Selling Stockholder		Number				Percentage(1)								Number				Percentage
Perceptive Life Science Master Fund Ltd.			1,086,199	(2)			3.99	%			1,086,199				—				—
Biotechnology Value Fund, LP			505,525	(3)			1.87	%			505,525				—				—
Biotechnology Value Fund II, LP			325,609	(4)			1.21	%			325,609				—				—
Biotechnology Value Trading Fund OS, LP			90,571	(5)			0.34	%			90,571				—				—
Investment 10, LLC			57,979	(6)			0.22	%			57,979				—				—
MSI BVF SPV, LLC			106,512	(7)			0.40	%			106,512				—				—
AJU Growth and Healthcare Fund			232,384	(8)			0.86	%			72,412				159,972				0.59	%
Santé Health Ventures Annex Fund, L.P.			869,492	(9)			3.23	%			14,482				855,010				3.18	%
Santé Health Ventures I, L.P.			7,916,608	(10)			29.43	%			57,930				7,858,678				29.21	%
Excel Venture Fund II, L.P.			1,497,696	(11)			5.57	%			72,412				1,425,284				5.30	%
Longitude Venture Partners III, L.P.			4,344,802	(12)			15.34	%			4,344,802				—				—
Baker Bros. Advisors, LP			108,618	(13)			0.40	%			108,618				—				—
CDK Associates L.L.C.			1,520,680	(14)			5.55	%			1,520,680				—				—
Shrewsbury Capital Partners LLC			217,239	(15)			0.81	%			217,239				—				—
Franklin M. Berger			108,619	(16)			0.40	%			108,619				—				—
Millennium Pharmaceuticals, Inc.			2,922,993	(17)			10.87	%			2,922,993				—				—

		Shares of Common Stock Beneficially Owned Before this Offering								Number of Shares of Common Stock Being Offered(3)				Shares of Common Stock To Be Beneficially Owned Upon Completion of this Offering
		Number				Percentage(2)								Number(4)				Percentage(2)(4)
Selling Stockholder(1)
Lytton-Kambara Foundation(5)			3,723,404				4.62	%			3,723,404				—				—
Adage Capital Partners, L.P.(6)			4,391,489				5.45	%			3,191,489				1,200,000				1.49	%
Entities affiliated with SilverArc Capital Management, LLC(7)			5,319,148				6.60	%			5,319,148				—				—
Entities affiliated with Monashee Investment Management LLC(8)			2,127,659				2.64	%			2,127,659				—				—
Entities affiliated with Empery Asset Management, LP(9)			2,127,659				2.64	%			2,127,659				—				—
Biotech Target N.V.(10)			15,447,322				19.16	%			4,255,319				11,192,003				13.88	%
Allostery Investments LP(11)			531,914				0.66	%			531,914				—				—
Entities affiliated with BVF Partners L.P.(12)			8,061,261				9.99	%			21,315,599				5,246,565				6.49	%

(5)

Consists The shares reported under “Shares of (i) 60,381Common Stock Beneficially Owned Before this Offering” consist of 3,723,404 shares of common stock held byCommon Stock purchased in the selling stockholder and (ii) 30,190 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. BVF Partners OS Ltd. (“BVF OS”), as the general partner of Biotechnology Value Trading Fund OS, LP (the “selling stockholder”), may be deemed to beneficially own the 60,381 shares of common stock and 30,190 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by the selling stockholder. Partners, as the sole shareholder of BVF OS, may be deemed to beneficially own the 60,381 shares of common stock and 30,190 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by BVF OS. BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 60,381 shares of common stock and 30,190 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by Partners. Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 60,381 shares of common stock and 30,190 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by BVF Inc. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any common stock owned by another Reporting Person. Each of BVF OS, Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the common stock beneficially owned by the selling stockholder, and the foregoing shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities. The selling stockholder’s address is Ugland House, South Church Street, George Town, Grand Cayman, KYI-1104, Cayman Islands.

(6)

Consists of (i) 38,653 shares of common stock held by the selling stockholder and (ii) 19,326 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. Partners, as the investment manager of Investment 10, LLC (the “selling stockholder”), may be deemed to beneficially own the 38,653 shares of common stock and 19,326 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by the selling stockholder. BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 38,653 shares of common stock and 19,326 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by Partners. Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 38,653 shares of common stock and 19,326 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by BVF Inc. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any common stock owned by another Reporting Person. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the common stock beneficially owned by the selling stockholder, and the foregoing shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities. The selling stockholder’s address is 900 N. Michigan Avenue, Suite 1100, Chicago, Illinois 60611.

(7)

Consists of (i) 71,008 shares of common stock held by the selling stockholder and (ii) 35,504 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. Partners, as the investment manager of MSI BVF SPV LLC (the “selling stockholder”), may be deemed to beneficially own the 71,008 shares of common stock and 35,504 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by the selling stockholder. BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 71,008 shares of common stock and 35,504 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by Partners. Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 71,008 shares of common stock and 35,504 shares of common stock issuable upon exercise of Warrants held by the selling stockholder that are beneficially owned by BVF Inc. The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any common stock owned by another Reporting Person. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the common stock beneficially owned by the selling stockholder, and the foregoing shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities. The selling stockholder’s address is Maples Corporate Services Ltd., PO Box 309, Ugland House, Grand Cayman, KYI-1104, Cayman Islands.

(8)

Includes (i) 208,247 shares of common stock held by AJU Growth and Healthcare Fund (“AJU Healthcare”) and (ii) 24,137 shares of common stock issuable upon the exercise of Warrants held by the AJU Healthcare. This figure excludes 1,080,562 shares of common stock held by AJU Life Science Overseas Platform Fund, an affiliate of the AJU Healthcare. The shares held by AJU Healthcare may be deemed to be beneficially owned by AJU IB Investment, Co., Ltd., its General Partner (“AJU IB”). AJU IB may be deemed to sharePrivate Placement. Laurence Lytton has voting andand/or investment power over the shares held by AJU Healthcare and disclaims beneficial ownership of such shares except to the extent of its pecuniary interest therein. AJU Healthcare’s address is 800 Boylston St., Suite 2510, Boston, Massachusetts 02199.

(9)

Consists of (i) 864,665 shares of common stock held by the selling stockholder and (ii) 4,827 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. The securities held by Sante Health Ventures I Annex Fund, L.P. may be deemed to be beneficially owned by Kevin Lalande, a member of our board of directors, Joe Cunningham, M.D. and Douglas D. French, who are managing directors (the “SHV Directors”) of SHV Management Services, LLC (“SHV Management”). SHV Management is the general partner of SHV Annex Services, LP, which is the general partner of Sante Health Ventures I Annex Fund, L.P. Each of the SHV Directors, SHV Management and SHV Annex Services, LP disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein. The selling stockholder’s address is 300 W. 6th Street, Suite 2300, Austin, Texas 78701.

(10)

Consists of (i) 7,897,298 shares of common stock held by the selling stockholder and (ii) 19,310 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. The securities held by Sante Health Ventures I, L.P. may be deemed to be beneficially owned by Kevin Lalande, a member of our board of directors, Joe Cunningham, M.D. and Douglas D. French, who are managing directors of SHV Management. SHV Management is the general partner of SHV Management Services, LP, which is the general partner of Sante Health Ventures I, L.P. Each of the SHV Directors, SHV Management and SHV Management Services, LP disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein. The selling stockholder’s address is 300 W. 6th Street, Suite 2300, Austin, Texas 78701.

(11)

Consists of (i) 1,473,559 shares of common stock held by the selling stockholder and (ii) 24,137 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. The securities held by Excel Venture Fund II, L.P. may be deemed to be beneficially owned by Steven R. Gullans, Juan Enriquez, Caleb M. Winder and Frederick R. Blume who are managing directors (the “Excel Directors”) of Excel Ventures II GP, LLC (“Excel GP”). Excel GP is the general partner of Excel Venture Fund II, L.P. Each of the Excel Directors and Excel GP may be deemed to share voting and investment power over the shares held by Excel Venture Fund II and disclaims beneficial ownership of such shares except to the extent of its, his or her pecuniary interest therein. The selling stockholder’s address is 800 Boylston Street, Suite 2825, Boston, MA 02199.

(12)

Consists of (i) 2,896,535 shares of common stock held by the selling stockholder and (ii) 1,448,267 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. Such securities are held by Longitude Venture Partners III, L.P. (“Longitude Venture III”)Lytton-Kambara Foundation and may be deemed to be beneficially owned by Longitude Capital Partners III, LLC (“Longitude Capital III”), David Hirsch, a memberthe beneficial owner of our board of directors (“Dr. Hirsch”), Patrick G. Enright (“these shares. Mr. Enright”), and Juliet Tammenoms Bakker (“Ms. Bakker”). Longitude Capital III is the general partner of Longitude Venture III and may be deemed to share voting and investment power over our securities held by Longitude Venture III. Dr. Hirsch, Mr. Enright and Ms. Bakker are members of Longitude Capital III and Mr. Enright and Ms. Bakker are the managing members of Longitude Capital III, and all of them may be deemed to share voting and investment power over our securities held by Longitude Venture III. Each of Longitude Capital III, Dr. Hirsch, Mr. Enright and Ms. BakkerLytton disclaims beneficial ownership of such securities except to the extent of its, his or her pecuniary interest therein. The selling stockholder’s address is 2740 Sand Hill Road, 2nd Floor, Menlo Park, California 94025.

(13)

The shares of common stock reported to us as beneficially owned by Baker Bros. Advisors LP (“BBA”) are held by the following selling stockholders: (i) 667, L.P. (“667”) (7,322 shares of common stock and 3,661 shares of common stock issuable upon exercise of Warrants held by the selling stockholder) and (ii) Baker Brothers Life Sciences, L.P. (“BBLS”) (65,090 shares of common stock and 32,545 shares of common stock issuable upon exercise of Warrants held by the selling stockholder). BBA is the management company and investment adviser to 667 and BBLS and may be deemed to beneficially own all of our securities held by 667 and BBLS. Baker Bros. Advisors (GP) LLC (“BBA-GP”) is the sole general partner of BBA. Julian C. Baker and Felix J. Baker have voting and investment power over our securities held by each of 667 and BBLS, as principals of BBA-GP. Julian C. Baker, Felix J. Baker, BBA and BBA-GP disclaim beneficial ownership of our securities held by 667 and BBLS, except to the extent of their pecuniary interest therein. The selling stockholder’s address is 667 Madison Avenue, New York, New York 10065.

(14)

Consists of (i) 1,013,787 shares of common stock held by the selling stockholder and (ii) 506,893 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. These shares are held by CDK Associates, L.L.C. and may be deemed to be beneficially owned by (x) Scott Morenstein, a member of our board of directors and a Managing Director of Caxton Alternative Management LP, the investment manager of CDK Associates, L.L.C., (y) Caxton Corporation, the manager of CDK Associates, LLC and (z) Bruce Kovner, the chairman and sole shareholder of Caxton Corporation. Caxton Corporation, Bruce Kovner and CDK Associates, L.L.C. may be considered directors by deputization due to their affiliation with Scott Morenstein. Each of Scott Morenstein, Caxton Corporation and Bruce Kovner disclaims beneficial ownership of these shares except to the extent of its or his pecuniary interest, if any, therein, and the foregoing shall not be deemed to be an admission that any such person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. The selling stockholder’s address is 731 Alexander Road, Building 2, Suite 500, Princeton, New Jersey 08540.

(15)

Consists of (i) 144,826 shares of common stock held by the selling stockholder and (ii) 72,413 shares of common stock issuable upon exercise of Warrants held by the selling stockholder. The securities held by the selling stockholder may be deemed to be beneficially owned by Jonathan E. Gold, the Managing Member of the selling stockholder. Mr. Gold may be deemed to share voting and investment power over the shares held by the selling stockholder and disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein. The selling stockholder’s address is PO Box 3322,467 Central Park West, 17-A, New York, New York 10163.NY 10025.

(16)(6)

Consists The shares reported under “Shares of Common Stock Beneficially Owned Before this Offering” consist of (i) 72,4133,191,489 shares of common stockCommon Stock purchased in the Private Placement and (ii) 1,200,000 shares of Common Stock. Bob Atchinson and Phillip Gross are the managing members of Adage Capital Advisors, L.L.C., which is the managing member of Adage Capital Partners GP, L.L.C., which is the general partner of Adage Capital Partners, L.P., and each such person or entity, as the case may be, has shared voting and/or investment power over the securities held by Adage Capital Partners, L.P. and may be deemed the selling stockholderbeneficial

12

13

Relationship with Selling Stockholders

As discussed in greater detail above under the section titled “Prospectus Summary-July 2023 Private Placement,” in July 2023, we entered into the Securities Purchase Agreement with the selling stockholders, pursuant to which we sold and issued shares of our Common Stock and Pre-Funded Warrants to purchase our Common Stock. Pursuant to the Securities Purchase Agreement, we also agreed to file a registration statement with the SEC to cover the resale by the selling stockholders of the shares of our Common Stock, including the shares of Common Stock issuable upon exercise of the Pre-Funded Warrants, issued pursuant to the Securities Purchase Agreement.

None of the selling stockholders has had a material relationship with us or any of our predecessors or affiliates within the past three years, other than as a result of the ownership of our shares of Common Stock or other securities.

None of the selling stockholders has held any position or office with us or our affiliates within the last three years.

14

PLAN OF DISTRIBUTION

The selling stockholders, which as used herein includes donees, pledgees, transferees or othersuccessors-in-interest selling shares of common stockCommon Stock or interests in shares of common stockCommon Stock received after the date of this prospectus from a selling stockholder as a gift, pledge, partnership distribution or other transfer, may, from time to time, sell, transfer or otherwise dispose of any or all of their shares of common stockCommon Stock or interests in shares of common stockCommon Stock on any stock exchange, market or trading facility on which the shares are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.

The selling stockholders may use any one or more of the following methods when disposing of shares or interests therein:

The selling stockholders may, from time to time, pledge or grant a security interest in some or all of the shares of common stockCommon Stock or Pre-Funded Warrants owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell thesuch shares of common stock,Common Stock or Pre-Funded Warrants, from time to time, under this prospectus, or under an amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act amending the list of selling stockholders to include the pledgee, transferee or other successors-in-interestsuccessors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer the shares of common stockCommon Stock or Pre-Funded Warrants in other circumstances, in which case the transferees, pledgees or other successors-in-interestsuccessors in interest will be the selling beneficial owners for purposes of this prospectus.

In connection with the sale of our common stockCommon Stock or interests therein, the selling stockholders may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of the common stockCommon Stock in the course of hedging the positions they assume. The selling stockholders may also sell shares of our common stockCommon Stock short and deliver these securities to close out their short positions, or loan or pledge the common stockCommon Stock to broker-dealers that in turn may sell these securities. The selling stockholders may also enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or other financial institution of shares offered by this prospectus, which shares such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

15

The aggregate proceeds to the selling stockholders from the sale of the common stockCommon Stock offered by them will be the purchase price of the common stockCommon Stock less discounts or commissions, if any. Each of the selling stockholders reserves the right to accept and, together with their agents from time to time, to reject, in whole or in part, any proposed purchase of common stockCommon Stock to be made directly or through agents. We will not receive any of the proceeds from this offering. Upon any exercise of the Pre-FundedWarrants by payment of cash, however, we will receive the exercise price of thePre-Funded Warrants.

The selling stockholders also may resell all or a portion of the shares in open market transactions in reliance upon Rule 144 under the Securities Act of 1933, provided that they meet the criteria and conform to the requirements of that rule.

The selling stockholders and any underwriters, broker-dealers or agents that participate in the sale of the common stockCommon Stock or interests therein may be “underwriters” within the meaning of Section 2(11) of the Securities Act. Any discounts, commissions, concessions or profit they earn on any resale of the shares may be underwriting discounts and commissions under the Securities Act. Selling stockholders who are “underwriters” within the meaning of Section 2(11) of the Securities Act will be subject to the prospectus delivery requirements of the Securities Act.

To the extent required, the shares of our common stockCommon Stock to be sold, the names of the selling stockholders, the respective purchase prices and public offering prices, the names of any agents, dealer or underwriter, any applicable commissions or discounts with respect to a particular offer will be set forth in an accompanying prospectus supplement or, if appropriate, a post-effective amendment to the registration statement of whichthat includes this prospectus is a part.prospectus.

In order to comply with the securities laws of some states, if applicable, the common stockCommon Stock may be sold in these jurisdictions only through registered or licensed brokers or dealers. In addition, in some states the common stockCommon Stock may not be sold unless it has been registered or qualified for sale or an exemption from registration or qualification requirements is available and is complied with.

We have advised the selling stockholders that the anti-manipulation rules of Regulation M under the Exchange Act may apply to sales of shares in the market and to the activities of the selling stockholders and their affiliates. In addition, to the extent applicable we will make copies of this prospectus (as it may be supplemented or amended from time to time) available to the selling stockholders for the purpose of satisfying the prospectus delivery requirements of the Securities Act. The selling stockholders may indemnify any broker-dealer that participates in transactions involving the sale of the shares against certain liabilities, including liabilities arising under the Securities Act.

We will pay allcertain expenses of the registration of the shares of common stockCommon Stock pursuant to the Registration RightsSecurities Purchase Agreement, including, without limitation, SEC filing fees and expenses of compliance with state securities or “blue sky” laws; provided, however, that each selling stockholder will pay all underwriting discounts and selling commissions, if any and any related legal expenses incurred by it. We will indemnify the selling stockholders against certain liabilities, including some liabilities under the Securities Act, in accordance with the Registration Rights Agreement,securities purchase agreement, or the selling stockholders will be entitled to contribution. We may be indemnified by the selling stockholders against civil liabilities, including liabilities under the Securities Act, that may arise from any written information furnished to us by the selling stockholders specifically for use in this prospectus, in accordance with the Registration Rightsrelated Securities Purchase Agreement, or we may be entitled to contribution.

We have agreed with the selling stockholders to keep the registration statement of which this prospectus isconstitutes a part effective until the earlier of (i)(1) such time as all of the shares covered by this prospectus have been disposed of pursuant to and in accordance with the registration statement or (ii)(2) the date on which all of the shares may be sold without restriction pursuant to Rule 144 of the Securities Act.

16

LEGAL MATTERS

The validity of the shares of common stockCommon Stock being offered inby this prospectus has beenis being passed upon for us by Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts.

EXPERTS

The consolidated financial statements of Threshold Pharmaceuticals,Molecular Templates, Inc. appearing in Threshold Pharmaceuticals, Inc.’sits Annual Report (Form10-K) for the year ended December 31, 20162022 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon (which contains an explanatory paragraph describing conditions that raise substantial doubt about the Company’s ability to continue as a going concern as described in Note 1 to the consolidated financial statements), included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND ADDITIONALMORE INFORMATION

We are subject to the informationreporting requirements of the Exchange Act, and we therefore file periodicannual, quarterly and current reports, proxy statements and other information with the SEC relating to our business, financial statements and other matters. The reports, proxy statements and other information we file may be inspected and copied at prescribed rates at the SEC’s Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the SEC’s Public Reference Room by calling the SEC at1-800-SEC-0330.SEC. The SEC also maintains aan internet website at www.sec.gov that contains periodic and current reports, proxy and information statements, and other information regarding issuers like usregistrants that fileare filed electronically with the SEC. The addressYou can request copies of these documents by writing to the SEC’s website is http://www.sec.gov.SEC and paying a fee for the copying cost.

This prospectus constitutesis only part of a registration statement on Form S-3 that we have filed with the SEC under the Securities Act, with respect to the shares of common stock covered hereby. As permitted by the SEC’s rules, this prospectusand therefore omits some of thecertain information exhibits and undertakings includedcontained in the registration statement. You may readWe have also filed exhibits and copyschedules with the information omittedregistration statement that are excluded from this prospectus, but contained inand you should refer to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document. You may obtain a copy of the registration statement, as well asincluding the periodic reportsexhibits and other information we file withschedules, from the SEC,SEC’s website.

We also maintain a website at the public reference room and website of the SEC referred to above. You may alsohttp://www.mtem.com, through which you can access our SEC filings with the SEC on our website, which is located at http://www.mtem.com/.free of charge. The information containedset forth on our website is not part of this prospectus.

Statements contained in this prospectus as to the contents of any contract or other document are not necessarily complete, and in each instance we refer you to the copy of the contract or other document filed or incorporated by reference as an exhibit to the registration statement or as an exhibit to our Exchange Act filings, each such statement being qualified in all respects by such reference.

17

INFORMATION INCORPORATEDINCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

We are allowedThe SEC allows us to incorporate“incorporate by referencereference” information contained in documents that we file with the SEC. Thisinto this prospectus, which means that we can disclose important information to you by referring you to those documents and thatanother document filed separately with the information in this prospectus is not complete and you should read theSEC. The information incorporated by reference for more detail. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prioris deemed to the datebe part of this prospectus, whileand subsequent information that we file later with the SEC will automatically update and supersede this information. We filed a registration statement on Form S-3 under the information in this prospectus.

We incorporate by reference the documents listed below and any future filings we will makeSecurities Act with the SEC under Sectionwith respect to the securities we may offer pursuant to this prospectus. This prospectus omits certain information contained in the registration statement, as permitted by the SEC. You should refer to the registration statement, including the exhibits, for further information about us and the securities we may offer pursuant to this prospectus. Statements in this prospectus regarding the provisions of certain documents filed with, or incorporated by reference in, the registration statement are not necessarily complete and each statement is qualified in all respects by that reference. Copies of all or any part of the registration statement, including the documents incorporated by reference or the exhibits, may be obtained from the SEC’s website at http://www.sec.gov. The documents we are incorporating by reference are:

Any statement contained in this prospectus but prioror in a document incorporated or deemed to the termination of the offering of the securities coveredbe incorporated by reference into this prospectus (other than Current Reportswill be deemed to be modified or portions thereof furnished under Item 2.02 or 7.01 of Form8-K):

Wethis prospectus to the extent that a statement contained in this prospectus or any other subsequently filed document that is deemed to be incorporated by reference into this prospectus modifies or supersedes the statement. Any statement so modified or superseded will providenot be deemed, except as so modified or superseded, to each person, including any beneficial owner, to whomconstitute a prospectus is delivered,part of this prospectus.

You may request, orally or in writing, a copy of any or all of the information that isdocuments incorporated herein by reference in this prospectus but not delivered with this prospectus, including exhibits that are specifically incorporated by reference in such documents. You may request a copy of suchreference. These documents which will be provided to you at no cost, by writing or telephoning us at the following address or telephone number:contacting:

MOLECULAR TEMPLATES, INC.Molecular Templates, Inc.

9301 Amberglen Blvd

Suite 100

Austin, TexasTX 78729

Attention: Chief Executive Officer

Telephone: (512)869-1555

You should rely only on information contained in, or incorporated by reference into, this prospectus. We and the selling stockholders have not authorized anyone to provide you with information different from that contained in

18

this prospectus or incorporated by reference in this prospectus. We and the selling stockholders are not making offers to sell the securities in any jurisdiction in which such an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make such offer or solicitation.

19

11,612,58242,592,191 Shares

Common Stock

PROSPECTUS

                , 2023

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

The following table setsItem 14. Other Expenses of Issuance and Distribution.

Set forth below is an estimate (except for registration fees, which are actual) of the approximate amount of the types of fees and expenses incurred and to be incurredlisted below that were paid or are payable by us in connection with the registrationissuance and distribution of the securities beingshares of Common Stock to be registered hereby, allby this registration statement. None of which willthe expenses listed below are to be borne by us. Except forany of the SECselling stockholders named in the prospectus that forms a part of this registration fee, all amounts are estimates.statement.

Item 15. Indemnification of Directors and Officers.

Delaware Law

Section 102 of the General Corporation Law of the State of Delaware (the “Delaware General Corporation Law”) permits a corporation to eliminate the personal liability of directors of a corporation to the corporation or its stockholders for monetary damages for a breach of fiduciary duty as a director, except where the director breached his duty of loyalty, failed to act in good faith, engaged in intentional misconduct or knowingly violated a law, authorized the payment of a dividend or approved a stock repurchase in violation of Delaware corporate law or obtained an improper personal benefit.

Section 145 of the Delaware General Corporation Law authorizesDGCL provides that a court to award, or a corporation’s board of directors to grant, indemnity to directors and officers in terms sufficiently broad to permit such indemnification under certain circumstances for liabilities, including reimbursement for expenses incurred, arising undercorporation has the Securities Act.

Section 145 of the Delaware General Corporation Law states:

(a) A corporation shall have power to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that the person is or was a director, officer, employee, or agent of the corporation, or is or wasa person serving at the request of the corporation as a director, officer, employee or agent offor another corporation, partnership, joint venture, trust or other enterprise in related capacities against expenses, (includingincluding attorneys’ fees),fees, judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with suchan action, suit or proceeding to which he was or is a party or is threatened to be made a party to any action, suit or proceeding by reason of such position, if thesuch person acted in good faith and in a manner the personhe reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect toin any criminal action or proceeding, had no reasonable cause to believe the person’shis conduct was unlawful. The terminationunlawful, except that, in the case of any action, suit or proceeding by judgment, order, settlement, conviction, or upon a plea of nolo contendere or its equivalent, shall not, of itself, create a presumption that the person did not act in good faith and in a manner which the person reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had reasonable cause to believe that the person’s conduct was unlawful.

(b) A corporation shall have power to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suitactions brought by or in the right of the corporation, to procure a judgment in its favor by reason of the fact that the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against expenses (including attorneys’ fees)

II-1

actually and reasonably incurred by the person in connection with the defense or settlement of such action or suit if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation and except that no indemnification shall be made inwith respect ofto any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or theother adjudicating court in which such action or suit was brought shall determine upon applicationdetermines that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem proper.

(c) To the extentAmended and Restated Bylaws

Our amended and restated bylaws provide that we will indemnify each person who was or is a presentparty or former director or officer ofthreatened to be made a corporation has been successful on the merits or otherwise in defense ofparty to any action, suit or proceeding, whether civil, criminal, administrative or investigative by reason of the fact that he or she is or was, or is or was serving at our request, as a director, officer, partner, employee or trustee of, or in a similar capacity with, another corporation, partnership, joint venture, trust or other enterprise (all such persons being referred to in subsections (a) and (b) of this section,as an “Indemnitee”), or in defenseby reason of any claim, issueaction alleged to have been taken or matter therein,omitted in such person shall be indemnifiedcapacity, against expensesall expense, liability and loss (including attorneys’ fees) actuallyfees, judgments, fines, ERISA excise taxes or penalties and amounts paid in settlement) reasonably incurred by such person in connection therewith.

(d) Any indemnification under subsections (a) and (b) of this section (unless ordered by a court) shall be made by the corporation only as authorized in the specific case upon a determination that indemnification of the present or former director, officer, employee or agent is proper in the circumstances because the person has met the applicable standard of conduct set forth in subsections (a) and (b) of this section. Such determination shall be made, with respect to a person who is a director or officer of the corporation at the time of such determination:

(1) By a majority vote of the directors who are not parties to such action, suit or proceeding even though less thanand any appeal therefrom, to the fullest extent allowed under the DGCL. Our

II-1

amended and restated bylaws also provide that we shall advance to any person who was or is a quorum;party or

(2) By is threatened to be made a committee of such directors designated by majority vote of such directors, even though less than a quorum;party to any action, suit or

(3) If there are no such directors, or if such directors so direct, by independent legal counsel in a written opinion; or

(4) By the stockholders.

(e) Expenses (including attorneys’ fees) incurred by an officer or director of the corporation in defending any proceeding, whether civil, criminal, administrative or investigative, action, suit or proceeding may be paid by the corporation in advancereason of the final disposition of such action, suitfact that he or proceeding upon receipt of an undertaking byshe is or on behalf of suchwas a director or executive officer to repay such amount if it shall ultimately be determined that such person is not entitled to be indemnified by the corporation as authorized in this section. Such expenses (including attorneys’ fees) incurred by former directors and officers or other employees and agents of the corporationCompany, or by personsis or was serving at theour request of the corporation as directors, officers, employeesa director or agentsexecutive officer of another corporation, partnership, joint venture, trust or other enterprise, may be so paid uponprior to the final disposition of the proceeding, promptly following request therefor, all expenses incurred by any director or executive officer in connection with such terms and conditions,proceeding. However, if any, as the corporation deems appropriate.

(f) The indemnification andDGCL requires, an advancement of expenses providedincurred by or granted pursuant to, the other subsections of this section shall not be deemed exclusive of any other rights to which those seeking indemnification or advancement of expenses may be entitled under any bylaw, agreement, vote of stockholders or disinterested directors or otherwise, both as to action in such person’s official capacity and as to action in another capacity while holding such office. A right to indemnification or to advancement of expenses arising under a provision of the certificate of incorporation or a bylaw shall not be eliminated or impaired by an amendment to the certificate of incorporation or the bylaws after the occurrence of the act or omission that is the subject of the civil, criminal, administrative or investigative action, suit or proceeding for which indemnification or advancement of expenses is sought, unless the provision in effect at the time of such act or omission explicitly authorizes such elimination or impairment after such action or omission has occurred.

(g) A corporation shall have power to purchase and maintain insurance on behalf of any person who is or was a director or executive officer employeein his or agent of the corporation, or is or was serving at the request of the corporationher capacity as a director or executive officer employee(and not in any other capacity in which service was or agent of another corporation, partnership, joint venture, trust or other enterprise against any liability asserted against such person and incurredis rendered by such person in any such capacity, or arising out of such person’s status as such, whether or not the corporation would have the power to indemnify such person against such liability under this section.

II-2

(h) For purposes of this section, references to “the corporation” shall include, in addition to the resulting corporation, any constituent corporation (including any constituent of a constituent) absorbed in a consolidation or merger which, if its separate existence had continued, would have had power and authority to indemnify its directors, officers, and employees or agents, so that any person who is or was a director, officer, employee or agent of such constituent corporation, or is or was serving at the request of such constituent corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, shall stand in the same position under this section with respect to the resulting or surviving corporation as such person would have with respect to such constituent corporation if its separate existence had continued.

(i) For purposes of this section, references to “other enterprises” shall include employee benefit plans; references to “fines” shall include any excise taxes assessed on a person with respect to any employee benefit plan; and references to “serving at the request of the corporation” shall include anyindemnitee, including service as a director, officer, employee or agent of the corporation which imposes duties on, or involves services by, such director, officer, employee or agent with respect to an employee benefit plan, its participantsplan) shall be made only upon delivery to us of an undertaking by or beneficiaries; and a person who acted in good faith and in a manneron behalf of such person reasonably believedindemnitee, to repay all amounts so advanced if it shall ultimately be determined by final judicial decision from which there is no further right to appeal that such indemnitee is not entitled to be in the interest of the participants and beneficiaries of an employee benefit plan shall be deemed to have acted in a manner “not opposed to the best interests of the corporation” as referred to in this section.

(j) The indemnification and advancement ofindemnified for such expenses provided by, or granted pursuant to, this section shall, unless otherwise provided when authorized or ratified, continue as to a person who has ceased to be a director, officer, employee or agent and shall inure to the benefit of the heirs, executors and administrators of such a person.

(k) The Court of Chancery is hereby vested with exclusive jurisdiction to hear and determine all actions for advancement of expenses or indemnification brought under this section or under any bylaw, agreement, vote of stockholders or disinterested directors, or otherwise. The Court of Chancery may summarily determine a corporation’s obligation to advance expenses (including attorneys’ fees).

As permitted by Delaware law, our amended and restated certificate of incorporation limitsbylaws or eliminates the personal liability of our directors to the maximum extent permitted by Delaware law.otherwise.

Our amendedIndemnification Agreements and restated bylaws provide for indemnification of our directors and executive officers to the maximum extent permitted by the Delaware General Corporation Law.Insurance Matters

In addition, we have entered into indemnification agreements with each of our current directors and we intend to enter into new indemnification agreements with certain of our executive officers. These agreements will require us to indemnify these individuals to the fullest extent permitted under Delaware law against liabilities that may arise by reason of their service to us and to advance expenses incurred as a result of any proceeding against them as to which they could be indemnified. We also intend to enter into indemnification agreements with our future directors and executive officers.

We also maintain standard policies of insurance under which coverage is provided to our directors and officers against losses arising from claims made by reason of breach of duty or other wrongful act, and to us with respect to payments which may be made by us to such directors and officers pursuant to the above indemnification provisions or otherwise as a matter of lawlaw.

The above discussion of our amended and restated certificate of incorporation, as amended, our amended and restated bylaws, our indemnification agreements with our current directors and executive officers and Sections 102 and 145 of the Delaware General Corporation LawDGCL is not intended to be exhaustive and is respectively qualified in its entirety by such amended and restated certificate of incorporation, such amended and restated bylaws, such indemnification agreements and such statutes.

II-3

To the extent that our directors, officers and controlling persons are indemnified under the provisions contained in our amended and restated certificate of incorporation, as amended, Delaware law or contractual arrangements against liabilities arising under the Securities Act, we have been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

EXHIBIT INDEXItem 16. Exhibits and Financial Statements Schedules.

The exhibits to this registration statement are listed in the Exhibit Index immediately prior the signature page hereto, which Exhibit Index is hereby incorporated by reference into this Item 16.

Item 17. Undertakings.

(a) The undersigned registrant hereby undertakes:

(1)

II-4II-2

Providedprovided, however, that paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Sectionsection 13 or Sectionsection 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act to any purchaser:

(i) If the registrant is relying on Rule 430B:

(2)

That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(ii) If the registrant is subject to Rule 430C, each prospectus filed pursuant to Rule 424(b) as part of a registration statement relating to an offering, other than registration statements relying on Rule 430B or other than

II-3

II-4

EXHIBIT INDEX

II-5

prospectuses filed in reliance on Rule 430A, shall be deemed to be part of and included in the registration statement as of the date it is first used after effectiveness. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such first use, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such date of first use.

The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by a director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

II-6

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrantregistrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on FormS-3 and has duly caused this Registration Statementregistration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Austin, State of Texas, on September 15, 2017.August 10, 2023.

POWERSSIGNATURES AND POWER OF ATTORNEY

Each person whose signature appears belowWe, the undersigned officers and directors of Molecular Templates, Inc., hereby constitutesseverally constitute and appointsappoint Eric E. Poma, Ph.D. and Jason S. Kim and each of them as hissingly (with full power to each of them to act alone), our true and lawfulattorneys-in-fact and agents, with full power of substitution and resubstitution in each of them for him and in his name, place and stead, and in any and all capacities, to sign any and all amendments (including, without limitation, post-effective amendments andamendments) to this registration statements filedstatement (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462) to this registration statement,462(b) under the Securities Act of 1933), and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto each saidattorney-in-factattorneys-in-fact and agent,agents, and each of them, full power and authority to do and perform each and every act and thing requisite andor necessary to be done in connection therewith,and about the premises, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that each saidattorney-in-factattorneys-in-fact and agentagents or any of them or their or his substitutessubstitute or substitute,substitutes may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement onForm S-3 has been signed by the following persons in the capacities and on the dates indicated.