You are cordially invited to attend the 20162023 Annual Meeting of Stockholders of CytomX Therapeutics, Inc., a Delaware corporation.corporation (the “Company” or “CytomX”). The 20162023 Annual Meeting of Stockholders will be held on June 10, 2016,14, 2023, at 31:30 p.m., Pacific Time, atTime. The 2023 Annual Meeting of Stockholders will be convened and held entirely online to support and facilitate stockholder participation. You will be able to attend and participate online in the San Francisco Airport Marriott Waterfront, 1800 Old Bayshore Highway, Burlingame, CA 94010, for2023 Annual Meeting of Stockholders by visiting www.virtualshareholdermeeting.com/CTMX2023, where you will be able to listen to the meeting live, submit questions, and vote.

These items of business are more fully described in the proxy statementProxy Statement accompanying this Notice of Annual Meeting of Stockholders. The record date for the 20162023 Annual Meeting of Stockholders is April 12, 2016.17, 2023. Only stockholders of record at the close of business on that date are entitled to notice of, and to vote at, the 20162023 Annual Meeting of Stockholders or any adjournment thereof.

Your vote is very important. Whether or not you attend the 20162023 Annual Meeting of Stockholders in person,(by logging into www.virtualshareholdermeeting.com/CTMX2023), it is important that your shares be represented. You may voteWe encourage you to read the accompanying Proxy Statement and our Annual Report on Form 10-K for the year ended December 31, 2022, and submit your proxy on the Internet, by phone or by mail in accordance with the instructions in the Notice of Internet Availability of Proxy Materials. Please review the instructions on the proxy card or the information forwarded by your bank, broker or other holder of record regarding each of these voting options. If you receive more than one set of proxy materials or notice of internet availability because your shares are registered in different names or addresses, each proxy should be signed and submitted to ensure that all of your shares will be

We sent you a Notice of Internet Availability of Proxy Materials because the board of directors of CytomX Therapeutics, Inc. (the “Board”) is soliciting your proxy to vote at our 20162023 Annual Meeting of Stockholders to be held on June 10, 201614, 2023 at 31:30 p.m., Pacific Time,Time. The meeting will be held virtually, via a live webcast at www.virtualshareholdermeeting.com/CTMX2023. To attend the San Francisco Airport Marriott Waterfront, 1800 Old Bayshore Highway, Burlingame, CA 94010. live webcast, you will need your unique 16-digit control number provided on the Notice of Internet Availability of Proxy Materials.

We invite you to attend the annual meeting to vote on the proposals described in this proxy statement.Proxy Statement. However, you do not need to attend the meeting to vote your shares. Instead, you may vote by proxy over the Internet or by phone by following the instructions provided in the notice or, if you request printed copies of the proxy materials by mail, you may vote by mail.

The notice is being sent or made available

Pursuant to the rules adopted by the Securities and Exchange Commission (the “SEC”), we have elected to provide access to our Annual Meeting materials, which include this Proxy Statement and our Annual Report on Form 10-K for the year ended December 31, 2022 (the “Form 10-K”), over the internet in lieu of mailing printed copies. We will begin mailing the Notice of Internet Availability to our stockholders of record as of April 17, 2023 (the “Record Date”) for the first time on or about April 28, 201627, 2023. The Notice of Internet Availability will contain instructions on how to all stockholdersaccess and review the 2023 Annual Meeting materials, how to access the live webcast of the 2023 Annual Meeting of Stockholders, and will also contain instructions on how to request a printed copy of the 2023 Annual Meeting materials. In addition, we have provided brokers, dealers, banks, voting trustees and their nominees, at our expense, with additional copies of our proxy materials and the Form 10-K so that our record entitledholders can supply these materials to votethe beneficial owners of shares of our common stock as of the Record Date. The Form 10-K is also available in the “Financial & Filings” section of our website at the annual meeting.

http://ir.cytomx.com/financial-information/annual-reports.

As used in this proxy statement,Proxy Statement, “CytomX,” the “Company,” “we” or “us” refer to CytomX Therapeutics, Inc., a Delaware corporation.

Only stockholders of record at the close of business on April 12, 201617, 2023 will be entitled to vote at the annual meeting. On this record date,Record Date, there were 36,085,80966,338,938 shares of common stock outstanding and entitled to vote.

If, on April 12, 2016,17, 2023, your shares were registered directly in your name with our transfer agent, Computershare Trust Company, N.A., then you are a stockholder of record. The notice will be sent to you by mail and via the Internet directly by us. As a stockholder of record, you may vote in persononline during the live webcast of the meeting at the annual meetingwww.virtualshareholdermeeting.com/CTMX2023, or vote by proxy. Whether or not you plan to attend the annual meeting online, we urge you to vote on the Internet or by phone as instructed in the notice or by proxy by mail by requesting a paper copy of the proxy materials as instructed in the notice to ensure your vote is counted.

If, on April 12, 2016,18, 2023, your shares were held in an account at a brokerage firm, bank or other agent, then you are the beneficial owner of shares held in “street name” and the notice is being forwarded to you by that organization.

If you are a beneficial owner of shares registered in the name of your broker, bank or other agent, you should have received a notice and voting instructions from that organization rather than from us. Simply follow the instructions to ensure that your vote is counted. To vote in persononline at the annual meeting, you must obtain a valid proxy from your broker, bank or other agent. Follow the instructions from your broker, bank or other agent included with the notice, or contact your broker, bank or other agent.

agent to request a proxy form.

We provide Internet proxy voting to allow you to vote your shares online, with procedures designed to ensure the authenticity and correctness of your proxy vote instructions. However, please be aware that you must bear any costs associated with your Internet access, such as usage charges from Internet access providers and telephone companies.

A quorum of stockholders is necessary to take any action at the meeting, other than to adjourn the meeting. The presence, in persononline or by proxy duly authorized, of the holders of a majority of the outstanding shares of stock entitled to vote will constitute a quorum. On April 12, 2016,17, 2023, there were 36,085,80966,338,938 shares of common stock outstanding and entitled to vote.

Your shares will be counted towardstoward the quorum only if you submit a valid proxy or vote in persononline at the annual meeting. Abstentions and broker non-votes will be counted towardstoward the quorum requirement. If there is no quorum, the chairman of the annual meeting or a majority of the votes present at the annual meeting may adjourn the annual meeting to another date.

If you are a stockholder of record and you return a proxy card without marking any voting selections, your shares will be voted:

If any other matter is properly presented at the meeting, your proxy (one of the individuals named on your proxy card) will vote your shares using histheir best judgment.

Proposal 1 (the election of directors) and Proposal 3 and 4(non-binding advisory vote to approve the compensation of our named executive officers) are matters considered non-routine under the applicable rules. If you do not give yourA broker specificor other nominee cannot vote without instructions theon non-routine matters, and therefore there may be broker may not vote your sharesnon-votes on Proposals 1 3 and 4 and your shares will constitute broker non-votes which will be counted for purposes of determining whether a quorum exists but will not affect the outcome of these proposals.3. Proposal 2 involves a matter we believe to be(the ratification of the appointment of Ernst & Young LLP, as our independent registered public accounting firm for the year ending December 31, 2023) is considered routine and thus if you do not give instructions to yourunder applicable rules. A broker the brokeror other nominee may generally vote your shares in its discretion on Proposal 2routine matters, and therefore no broker non-votes are expected to exist in connection with Proposal 2.

We will pay for the entire cost of soliciting proxies. In addition to the notice and the proxy materials, our directors and employees may also solicit proxies in person,online, by telephone or by other means of communication. We will not pay our directors and employees any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding the notice and any other proxy materials to beneficial owners.

If you receive more than one notice, your shares are registered in more than one name or are registered in different accounts. Please vote by proxy according to each notice to ensure that all of your shares are voted.

Yes, you can revoke your proxy at any time before the final vote at the annual meeting. If you are a stockholder of record, you may revoke your proxy in any one of three ways:

If you are a beneficial owner, you may revoke your proxy by submitting new instructions to your broker, bank or other agent, or if you have received a proxy from your broker, bank or other agent giving you the right to vote your shares at the annual meeting, by attending our virtual annual meeting by visiting www.virtualshareholdermeeting.com/CTMX2023 with your 16-digit control number (available in your notice and proxy card) and following the instructions to vote online.

Pursuant to Rule 14a-8 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), some stockholder proposals may be eligible for inclusion in our 2017 proxy statement.statement for our 2024 Annual Meeting of Stockholders. Any such proposal must be submitted in writing by December 29, 2016,30, 2023, to our Secretary, care of

We have adopted a procedure approved by the SEC called “householding.” Under this procedure, stockholders who have the same address may receive only one copy of the notice,our annual report, proxy statement or Notice of Internet Availability of Proxy Materials, unless one or more of these stockholders notifies us that they wish to receive individual copies of the notice and, if requested, other proxy materials.such documents. This process potentially means extra convenience for stockholders and cost savings for companies.

Our board of directorsBoard currently consists of seven directors and is divided into three classes, designated as Class I, Class II and Class III. Under our amendedAmended and restated certificateRestated Certificate of incorporation,Incorporation, our board of directorsBoard is authorized to assign its members in office to each class. Each class has a term of three years. There are currently two directors in Class I, Sean A. McCarthy, D. Phil.II, Matthew P. Young and Elaine V. Jones, Ph.D., whose termterms of office expires upon the election of directorsare scheduled to expire at the 20162023 Annual Meeting of Stockholders. Each of Mr. Matthew P. Young and Dr. McCarthy, one of the current directors in Class I, hasElaine V. Jones have been nominated for election at the 20162023 Annual Meeting of Stockholders. Dr. Jones will not stand for re-election at the 2016 Annual Meeting of Stockholders. Dr. Jones has decided not to stand for re-election in order to focus on her other business interests.

Any vacancies on our board of directorsBoard resulting from death, resignation, disqualification, removal or other causes, and any newly created directorships resulting from any increase in the number of directors, shall be filled by the affirmative vote of a majority of the directors then in office, even though less than a quorum of the board of directors.Board. Any director elected to fill a vacancy shall hold office for the remainder of the unexpired term in which the vacancy occurred or newly created directorship was created and until such director’s successor shall have been elected and qualified.

Directors are elected by a majority of the votes cast at the annual meeting and entitled to vote on the election of directors. A majority of votes cast shall mean that the number of shares voted “For” a director’s election exceeds fifty percent50% of the number of votes cast with respect to that director’s election, with votes cast including votes “Against” in each case and excluding abstentions and broker non-votes with respect to that director’s election. Shares represented by executed proxies will be voted for the election of the two nominees named below, unless the “Against” or “Abstain” voting selection has been marked on the proxy card.

If any of Mr. Matthew P. Young or Dr. McCarthy becomesElaine V. Jones become unavailable for election as a result of an unexpected occurrence, shares that would otherwise be voted for himsuch director will be voted for the election of a substitute nominee proposed by the nominatingNominating and corporate governance committeeCorporate Governance Committee and nominated by the board of directors.Board. Mr. Matthew P. Young and Dr. McCarthy hasElaine V. Jones have agreed to serve if elected. Our management has no reason to believe that either of Mr. Matthew P. Young or Dr. McCarthyElaine V. Jones will be unable to serve. If elected at the annual meeting, each of Mr. Matthew P. Young and Dr. McCarthyElaine V. Jones will serve until the earliest of the 20192026 Annual Meeting of Stockholders, hisor their respective successor is elected and qualified, or hisuntil their respective death, resignation or removal.

The following is aare brief biographybiographies of Mr. Matthew P. Young and Dr. McCarthy,Elaine V. Jones, the nomineenominees for director, and a discussion of histheir specific experience, qualifications, attributes or skills that led the nominatingNominating and corporate governance committeeCorporate Governance Committee of the board of directorsBoard to recommend thateach of Mr. Young and Dr. McCarthy as a nomineeJones for director, as of the date of this proxy statement.

Mr. Matthew P. Young has served as a member of our boardBoard since September 2015. Mr. Young currently serves as a managing director at Longitude Capital, a position he has held since August 2022. Before that, Mr. Young was serving as chief operating officer and chief financial officer of directors and ourGRAIL from October 2019 to December 2021. Prior to joining GRAIL, Mr. Young had served as executive vice president and chief executivefinancial officer of Jazz Pharmaceuticals (“Jazz”), a role he held since August 2011. Previously, Dr. McCarthyFebruary 2015. He previously had served as oursenior vice president and chief businessfinancial officer from December 2010of Jazz since March 2014 and as senior vice president, corporate development of Jazz since April 2013. Prior to August 2011.joining Jazz, Mr. Young worked in investment banking for approximately 20 years. From February 2009 to April 2006 to December 2010,2013, he wasserved as a transactional partner at Pappas Ventures, a venture capitalmanaging director in global healthcare of Barclays Capital Inc., an investment banking firm, where he helped drive investments in therapeutic, medical device and molecular diagnostic companies. Priorhis role included acting as the co-head of life sciences at Barclays Capital. From 2007 to Pappas Ventures, Dr. McCarthy was the vice president2008, Mr. Young served as a managing director of business development at SGX Pharmaceuticals,Citigroup Global Markets Inc., where he spearheadedan investment banking firm, and, from 2003 to 2007, as a wide range of strategic collaborations with major pharmaceutical companies, and served on the management team that led to the initial public offering of the company in 2006, before the Company’s ultimate acquisition by Eli Lilly and Company. Prior to SGX Pharmaceuticals, Inc.,

Dr. McCarthy was associatemanaging director of program management at Millennium Pharmaceuticals,Lehman Brothers Inc., wherean investment banking firm. In 2015, he managed therapeutic protein programs and a research team that invented novel genomic techniques for the identification of therapeutic proteins. Dr. McCarthy is an author on multiple peer reviewed scientific publications and patent applications. Dr. McCarthy received his B.Sc. in biochemistry and pharmacology at King’s College, University of London, his D. Phil. in cancer biology from St. John’s College, University of Oxford and his M.B.A. from the Rady School at the University of California, San Diego. Dr. McCarthy currently serves onjoined the board of directors of PRA Health Sciences Inc., a contract research company. Mr. Young received a B.S. in economics and a M.B.A. from the California Life Sciences Association. The nominating and corporate governance committee believesWharton School of the University of Pennsylvania. We believe that Dr. McCarthy’sMr. Young is qualified to serve on our Board due to his extensive management experience, serving as our chief executive officer, combined with hissignificant experience in the biopharmaceuticallife sciences industry and the venture capital industries, provide him with the qualifications and skills to servefinancial expertise.

Dr. Elaine V. Jones has served as a member of our Board since May 2019. Dr. Jones retired in April 2019 from her role as vice president, worldwide business development and senior partner at Pfizer Ventures, the venture capital arm of Pfizer Inc. After joining Pfizer Ventures as executive director in 2008, Dr. Jones was responsible for making and managing venture investments for Pfizer as well as serving in Board roles for several therapeutic companies.

The audit committeeAudit Committee of our board of directorsBoard has selected PricewaterhouseCoopersErnst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 20162023 and has further directed that management submit the selection of our independent registered public accounting firm for ratification by the stockholders at the annual meeting. PricewaterhouseCoopersErnst & Young LLP has audited our financial statements for each of our fiscal years since the fiscal yearsyear ended December 31, 2015 and 2014.2017. Representatives of PricewaterhouseCoopersErnst & Young LLP are expected to be present at the virtual annual meeting. TheyDuring the webcast, they will have an opportunity to make a statement if they so desire and will be available to respond to appropriate questions.

questions submitted online.

Neither our bylaws nor other governing documents or law require stockholder ratification of the selection of PricewaterhouseCoopersErnst & Young LLP as our independent registered public accounting firm. However, the audit committeeAudit Committee is submitting the selection of PricewaterhouseCoopersErnst & Young LLP to the stockholders for ratification as a matter of good corporate practice. If the stockholders fail to ratify the selection, the audit committeeAudit Committee will reconsider whether or not to retain PricewaterhouseCoopersErnst & Young LLP. Even if the selection is ratified, the audit committee,Audit Committee, in its discretion, may direct the appointment of a different independent registered public accounting firm at any time during the year if the committeeAudit Committee determines that such a change would be in our best interests and our stockholders’ best interest.

The affirmative vote of the holders of a majority of the shares of our common stock present in persononline or represented by proxy at the annual meeting and entitled to cast votes on this proposal will be required to ratify the selection of PricewaterhouseCoopersErnst & Young LLP for our fiscal year ending December 31, 2016.2023. Abstentions will not be counted as votes cast on this proposal. No broker non-votes are expected to exist in connection with this proposal.

The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”) enables our stockholders will be askedto vote to approve, the CytomX Therapeutics, Inc. Annual Incentive Plan (the “Bonus Plan”) under which officers and other employees of the Company would be eligible to receive incentive payments based on the achievement of objective performance goals for performance periods commencing after June 10, 2016. The Bonus Plan was approved by the board of directors on April 15, 2016, subject to stockholder approval. If the Bonus Plan is approved by our stockholders at the annual meeting, it is intended that the Bonus Plan will qualify for exemption under Section 162(m) of the Internal Revenue Code of 1986, as amended (the “Code”), which would generally allow awards granted under the Bonus Plan to be tax deductible by us, assuming other applicable regulatory requirements are satisfied.

The Bonus Plan will allow the Compensation Committee to utilize specified financial or individual measures (as more fully described below) when determining awards under the Bonus Plan. Section 162(m) limits the deduction for federal income tax purposes of compensation for the chief executive officer and certain other most highly compensated executive officers as of the last day of a company’s taxable year (collectively, the “162(m) covered employees”) to $1 million per year, unless such compensation qualifies as “performance-based compensation” under Section 162(m). Various requirements must be satisfied in order for compensation paid to the 162(m) covered employees to qualify as performance-based compensation within the meaning of Section 162(m). One such requirement is thatan advisory, non-binding basis, the compensation must be paid based upon the attainment of performance measures established by a committee of board members, or a subcommittee thereof, meeting the definition of “outside director” as defined in Section 162(m). In addition, the measures established by such a committee must be based upon performance measures, the material terms of which are approved by the stockholders.

We are accordingly requesting the stockholders to approve the Bonus Plan in accordance with Section 162(m). If stockholders do not approve the Bonus Plan in accordance with Section 162(m), then the compensation committee will re-evaluate the compensation program in order to continue to provide compensation to attract, retain and motivate its executive officers.

The following is a description of the Bonus Plan. This description is qualified in its entirety by reference to the Bonus Plan, a copy of which has been included as Appendix A to this proxy statement.

Description of the Bonus Plan

The purpose of the Bonus Plan is to retain and motivate officers and other employees of the Company who are designated by the compensation committee to participate in the Bonus Plan for a specified performance period commencing after June 10, 2016 (a “Performance Period”) by providing such designated officers and employees with the opportunity to earn incentive payments based upon the extent to which specified performance goals have been achieved or exceeded for that Performance Period. The Bonus Plan will be administered by the compensation committee, which is comprised solely of independent directors.

All officers and other employees of the Company and its subsidiaries are eligible to be designated as participants in the Bonus Plan. The compensation committee, in its discretion, will designate the eligible employees who will participate in the Bonus Plan for a specified Performance Period, and will do so not later than 90 days after the beginning of the Performance Period or, if earlier, not later than the date on which 25% of the Performance Period has been completed (the “Applicable Period”). As of April 12, 2016, approximately 65 officers and other employees would have been eligible to participate in the Bonus Plan; however, it is anticipated that only our executive officers (currently, five individuals) will be eligible to receive awards under the Bonus Plan.

Under the Bonus Plan, payment of awards to participating employees is subject to the attainment of specific performance goals and other terms and conditions established by the compensation committee during the Applicable Period for each Performance Period. A participant may receive an award under the Bonus Plan based upon achievement of a performance goal or goals using one or more objective corporate-wide or subsidiary, division, operating unit or individual measures. With respect to bonuses payable to persons who are, or are expected to be, employed as the chief executive officer or certain of the other most highly compensated executive officers of the Company as of the last day of the Company’s taxable year (“162(m) Covered Employees”) and to the extent necessary for an award to be qualified performance-based compensation under Section 162(m) of the Code, the applicable performance goals shall be based exclusively on one or more of the following objective corporate-wide or subsidiary, division, operating unit or individual measures: the attainment by a share of a specified fair market value for a specified period of time; earnings per share; return to stockholders (including dividends); return on assets; return on equity; earnings of the Company before or after taxes and/or interest; revenues; expenses; market share; cash flow or cost reduction goals; interest expense; return on investment; return on investment capital; return on operating costs; economic value created; operating margin; gross margin; the achievement of annual operating profit plans; net income; earnings before interest, depreciation and/or amortization; operating earnings after interest expense and before incentives, and/or extraordinary or special items; operating earnings; net cash provided by operations; and strategic business criteria, consisting of one or more objectives based on meeting specified market penetration, geographic business expansion goals, cost targets, days sales outstanding goals, customer satisfaction, reductions in errors and omissions, reductions in lost business, management of employment practices and employee benefits, supervision of litigation and information technology, quality and quality audit scores, productivity, efficiency, and goals relating to acquisitions or divestitures, or any combination of the foregoing. Each such goal may be expressed on an absolute or relative basis and may include comparisons based on current internal targets, the past performance of the Company (including the performance of one or more subsidiaries, divisions, or operating units) or the past or current performance of other companies (or a combination of such past and current performance). In the case of earnings-based measures, in addition to the ratios specifically enumerated above, performance goals may include comparisons relating to capital (including, but not limited to, the cost of capital), stockholders’ equity, shares outstanding, assets or net assets, or any combination thereof. The applicable performance measures may be applied on a pre- or post-tax basis and may be adjusted in accordance with Section 162(m) of the Code to include or exclude objectively determinable components of any performance measure, including, without limitation, special charges such as restructuring or impairment charges, debt refinancing costs, extraordinary or noncash items, unusual, nonrecurring or one-time events affecting the Company or its financial statements or changes in law or accounting principles. With respect to participants who are not “covered employees” within the meaning of Section 162(m) of the Code and who, in the Committee’s judgment, are not likely to be covered employees at any time during the applicable Performance Period, the performance goals established for the Performance Period may consist of any objective or subjective corporate-wide or subsidiary, division, operating unit or individual measures, whether or not listed herein.

If the relevant performance goals are attained during the Performance Period, a participant will be eligible to receive a cash award. Performance goal targets are expressed in terms of an objective formula or standard which may be based on an employee’s base salary, or a multiple thereof, at the time or immediately before the performance goals for such Performance Period were established. In all cases, the compensation committee has the sole and absolute discretion to reduce the amount of any payment under the Bonus Plan that would otherwise be made to any participant or to decide that no payment shall be made. No participant will receive a payment under the Bonus Plan with respect to any Performance Period having a value in excess of $3,000,000, which maximum amount will be proportionally adjusted with respect to Performance Periods that are less than or more than one year in durations.

Determination of the performance compensation awarded to each participant is to be made at a time determined by the compensation committee after the last day of each Performance Period following a certification by the compensation committee that the applicable performance goals were satisfied. During the Applicable Period, the compensation committee will establish terms regarding the timing of payment of awards.

The compensation committee may delegate its responsibilities under the Bonus Plan to our chief executive officer or such other executive officer of the Company as it deems appropriate, except that the compensation committee may not delegate its responsibilities with respect to bonuses payable to 162(m) Covered Employees. No compensation will be paid under the Bonus Plan to 162(m) Covered Employees if the Bonus Plan is not approved by stockholders. If approved, the Bonus Plan will be effective for Performance Periods commencing June 10, 2016. The board of directors may terminate the Bonus Plan at any time.

New Plan Benefits

The value of the performance-based awards granted under the Bonus Plan is subject to performance objectives established by the compensation committee and is, therefore, not determinable. Please see the “2015 Summary Compensation Table” for the value of payouts received under the Company’s annual bonus plan by each of our named executive officers for performanceas disclosed in 2015.

The affirmativethis Proxy Statement in accordance with the SEC’s rules, commonly known as a “Say-on-Pay” vote. Accordingly, we are seeking a non-binding, advisory vote of the holders of a majority of the shares of our common stock present in person or represented by proxy at the annual meeting and cast on this proposal will be required to approve the compensation of our named executive officers as described in the “Executive Compensation Summary” section of this Proxy Statement and the compensation tables and accompanying narrative disclosures that follow.

While the vote on this proposal.

resolution is advisory and not binding on us, the Compensation Committee, or our Board, the Compensation Committee and our Board values thoughtful input from stockholders and will consider the outcome of the vote on this resolution when considering future executive compensation decisions. Our Board has adopted a policy of providing for annual advisory votes from stockholders on executive compensation. Unless our Board modifies its policy on the frequency of future Say-on-Pay advisory votes, the next Say-on-Pay advisory vote will be held at the 2024 annual meeting of stockholders.

The following table sets forth certain information regarding the ownership of our common stock as of March 31, 2016,April 17, 2023, by: (i) each director;of our directors; (ii) each of our named executive officers; (iii) all of our executive officers and directors as a group; and (iv) all those known by us to be beneficial owners of more than five percent5% of our common stock.

		Beneficial Ownership**
Beneficial Owner		Number of Shares				Percent of Total
Third Rock Ventures, L.P.(1)			8,670,348				24.03	%
FMR LLC(2)			5,403,643				14.97	%
Canaan IX L.P.(3)			4,884,755				13.54	%
Pfizer Inc.(4)			2,017,604				5.59	%
CytomX Therapeutics Holdings, LLC(5)			2,252,976				6.24	%
Roche Finance Ltd(6)			1,903,579				5.28	%
Sean A. McCarthy, D. Phil.(7)			869,324				2.36	%
Neil Exter			—				—
Frederick W. Gluck(8)			249,115				*	%
Hoyoung Huh, M.D., Ph.D.(9)			359,993				0.99	%
Elaine V. Jones, Ph.D.			—				—
Timothy M. Shannon, M.D.			—				—
Matthew P. Young(10)			26,895				*	%
Robert C. Goeltz II(11)			86,560				*	%
Rachel W. Humphrey, M.D.(12)			54,624				*	%
W. Michael Kavanaugh, M.D.(13)			104,603				*	%
All executive officers and directors as a group (11 persons)(14)			1,762,998				4.70	%

On April 17, 2023, there were 66,338,938 shares of common stock outstanding and entitled to vote. Unless otherwise indicated below, the address for each beneficial owner listed is c/o CytomX Therapeutics, Inc., at 151 Oyster Point Boulevard, Suite 400, South San Francisco, California.

Section 16(a) of the Exchange Act requires our directors and executive officers, and persons who beneficially own more than ten percent10% of a registered class of our equity securities, to file with the SEC initial reports of ownership and reports of changes in ownership of our common stock and other equity securities. Officers, directors and greater than ten percent10% beneficial owners are required by SEC regulations to furnish us with copies of all Section 16(a) forms they file.

To our knowledge, based solely on our review of Forms 3, 4 and 5, and any amendments thereto, furnished to us or written representations, that no Form 5 was required, we believe that during the fiscal year ended December 31, 2015,2022, all filing requirements applicable to our executive officers and directors under the Exchange Act were met in a timely mannermanner.

We have adopted a written related party transactions policy, which sets forth the policies and procedures for the review and approval or ratification of related party transactions. The policy covers, with certain exceptions set forth in Item 404 of Regulation S-K promulgated under the Exchange Act, any transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships, in which we were or are to be a participant, where the amount involved exceeds $120,000 and a related party had, has or will have a direct or indirect material interest, including indebtedness, guarantees of indebtedness and employment by us of a related party.

A related party transaction reviewed under the policy will be considered approved or ratified if it is authorized by the audit committeeAudit Committee of our board of directorsBoard or the chairperson of the audit committeeAudit Committee in accordance with the standards set forth in the policy after full disclosure of the related party’s interests in the transaction. As appropriate for the circumstances, the audit committeeAudit Committee or the chairperson of the audit committee,Audit Committee, as applicable, shall review and consider:

We describe below transactions and series of similar transactions since January 1, 2015,2021, to which we were a party or will be a party, in which (i) the amounts involved exceeded or will exceed $120,000 and (ii) any of our directors, executive officers, holders of more than five percent5% of our capital stock or any member of their immediate family had or will have a direct or indirect material interest, other than compensation arrangements with directors and executive officers, which are described where required in the sections titled “Director Compensation” and “Executive Compensation,” respectively, in this proxy statement.

Participation in the initial public offering

Certain holders of more than five percent of our capital stock and their affiliated entities and one of our directors purchased shares of our common stock in the initial public offering of our common stock, which closed on October 14, 2015 (the “IPO”), from the underwriters for payment in excess of $120,000 as summarized in the following table. The underwriters received the same underwriting discount from the sale of the shares of our common stock to these holders as they did from other shares of our common stock sold to the public in the IPO.

Participants		Number of Shares of Common Stock Purchased				Aggregate Purchase Price ($)
Entities affiliated with Fidelity Management & Research Company			2,777,500				33,330,000
Pfizer Inc.			416,666				4,999,992
Frederick W. Gluck(1)			15,000				180,000

(1)	Consists of (a) 10,000 shares of our common stock purchased by Frederick W. Gluck and (b) 5,000 shares of our common stock purchased by Richlin Partners, LLC, an entity owned by the spouse of Frederick W. Gluck.

Issuance of preferred stock in 2015

In February 2015 and May 2015, we issued and sold an aggregate of 941,842 shares of our Series C preferred stock at a purchase price of $5.309387 per share for an aggregate purchase price of approximately $5.0 million in cash, including (i) 659,209 shares issued to Canaan IX L.P. for an aggregate purchase price of approximately $3.5 million and (iii) 282,633 shares issued to CytomX Therapeutics Holdings, LLC for an aggregate purchase price of approximately $1.5 million.

In June 2015, we issued and sold an aggregate of 7,490,540 shares of our Series D preferred stock at a purchase price of $9.345101 per share for an aggregate purchase price of approximately $70.0 million in cash, including 2,461,177 shares issued to entities affiliated with Fidelity Management & Research Company for an aggregate purchase price of approximately $23.0 million.

Name		Number of Shares of Series C Preferred Stock				Number of Shares of Series D Preferred Stock
Entities affiliated with Fidelity Management & Research Company(1)			—				2,461,177
Canaan IX L.P.(2)			659,209				—
CytomX Therapeutics Holdings, LLC			282,633				—

(1)

Consists of (a) 287,485 shares purchased by Fidelity Select Portfolios: Biotechnology Portfolio, (b) 64,961 shares purchased by Fidelity Advisory Series VII: Fidelity Advisor Biotechnology Fund, (c) 189,110 purchased by Fidelity Growth Company Commingled Pool, (d) 207,739 shares purchased by Fidelity Mt. Vernon Street Trust: Fidelity Series Growth Company Fund, (e) 794,033 shares purchased by Fidelity Mt. Vernon Street Trust: Fidelity Growth Company Fund, (f) 105,499 shares purchased by Fidelity Securities Fund: Fidelity Series Small Cap Opportunities Fund—Healthcare Sub, (g) 27,627 shares purchased by Fidelity Capital Trust: Fidelity Stock Selector Small Cap Fund—Health Care Sub, (h) 2,584 shares purchased by Fidelity Blue Chip Growth Commingled Pool, (i) 137,854 shares purchased by Fidelity Securities Fund: Fidelity Series Blue Chip Growth Fund, (j) 378,621 shares purchased by Fidelity Securities Fund: Fidelity Blue Chip Growth Fund, (k) 4,032 shares purchased by Fidelity OTC Commingled Pool, (l) 244,269 shares purchased by Fidelity Securities Fund: Fidelity OTC Portfolio and (m) 17,363 shares purchased by Pyramis Lifecycle Blue Chip Growth Commingled Pool.

(2)

Consists of 659,209 shares of Series C preferred stock purchased by Canaan IX L.P. Timothy M. Shannon, M.D., a member of our board of directors, is a non-managing member of Canaan Partners IX LLC, the general partner of Canaan IX L.P. Dr. Shannon does not have voting or investment power over any of the shares directly held by Canaan IX L.P.

Investors’ Rights Agreement

We are party to an amended and restated investors’ rights agreement, dated as of June 12, 2015, pursuant to which certain of our stockholders, including certain holders of five percent or more of our capital stock and entities affiliated with certain of our directors, have the right to demand that we file a registration statement for their shares of our common stock or request that their shares of our common stock be covered by a registration statement that we are otherwise filing, including, in each case, shares of our common stock that were issued upon conversion of convertible preferred stock.

Demand Registration Rights

At any time after 180 days following the completion of the IPO on October 14, 2015, the holders of at least a majority of the registrable securities have the right to demand that we file, on no more than two occasions, a registration statement on Form S-1 to register all or a portion of their registrable securities, provided that the anticipated aggregate offering price of the registrable securities to be sold under the registration statement on Form S-1 exceeds $30 million, net of underwriting discounts and commissions.

Form S-3 Registration Rights

After the closing of this offering, the holders of at least ten percent of the registrable securities have the right to demand that we file an unlimited number of registration statements on Form S-3 provided that the anticipated aggregate offering price of the registrable securities to be sold under the registration statement on Form S-3 exceeds $5 million, net of underwriting discounts and commissions.

Piggyback Registration Rights

If we propose to register any of our securities under the Securities Act of 1933, as amended (the “Securities Act”), for sale to the public, other than with respect to (i) any employee benefit plan, (ii) with respect to any corporate reorganization or transaction under Rule 145 of the Securities Act, any registration statements related to the issuance or resale of securities issued in such a transaction, (iii) a registration on any form that does not include substantially the same information as would be required to be included in a registration statement covering the sale of registrable securities, or (iv) a registration related to stock issued upon conversion of debt securities, the holders of registrable securities are entitled to receive notice of such registration and to request that we include their registrable securities for resale in the registration statement. The underwriters of the offering will have the right to limit the number of shares to be included in such registration.

Expenses of Registration; Indemnification

We are generally required to bear all registration expenses incurred in connection with any offerings pursuant to the demand, Form S-3 and piggyback registration rights described above, other than underwriting commissions and discounts. The amended and restated investors’ rights agreement contains customary indemnification provisions with respect to registration rights.

Termination of Registration Rights

The demand, Form S-3 and piggyback registration rights described above will terminate five years after the closing of the IPO. In addition, the registration rights of a holder of registrable securities will expire if all of the holder’s registrable securities may be sold without limitation (and without the requirement for us to be in compliance with the current public information requirement) under Rule 144 of the Securities Act.

Collaboration Agreement

Pfizer is one of our stockholders that owns more than five percent of our capital stock. In May 2013, we entered into a research collaboration, option and license agreement with it, pursuant to which we granted Pfizer the option to collaborate with us on preclinical research of PDCs and certain other rights in exchange for certain fees and royalties on potential future sales. Since January 1, 2015, a total of approximately $641,000 in research funding has been paid or become payable by Pfizer to us under the research collaboration, option and license agreement. In addition, upon the selection of certain targets pursuant to the collaboration agreement, it will be required to pay us additional amounts. Pfizer also has obligations to pay us certain licensing and royalty amounts.

Proxy Statement.

We have entered employment-related agreements with our executive officers. See section titled “Executive Compensation Summary,” respectively, in this proxy statementProxy Statement for more information regarding each of these agreements and compensation of our directors and executive officers.

Note Receivable

In December 2010, we accepted a full-recourse promissory note in the amount of $180,000 from Sean A. McCarthy, D.Phil. as consideration for the exercise price for options to purchase an aggregate of 158,737 shares of our common stock. The note accrued an interest at a rate of 1.53% per annum. Dr. McCarthy has paid all amounts owed under the note, and the note has been cancelled.

We have entered into indemnification agreements with each of our directors and executive officers. These agreements, among other things, require us or will require us to indemnify each director (and in certain cases their affiliated venture capital funds) and executive officer to the fullest extent permitted by Delaware law, including indemnification of expenses such as attorneys’ fees, judgments, fines and settlement amounts incurred by the director or executive officer in any action or proceeding, including any action or proceeding by or in right of us, arising out of the person’s services as a director or executive officer.

The following are brief biographybiographies of eachour current director, including the one nominee for election at the 2016 Annual Meeting of Stockholders to a new term of office, the director whose term of office will expire at the 2016 Annual Meeting of Stockholders and each directordirectors whose current term of office continues through the 20162023 Annual Meeting of Stockholders.

Class I Director Nominated for Election Biographies of our two current directors who are being nominated to a new term of office at the 20162023 Annual Meeting of Stockholders

are included above under “Proposal No. 1 Election of Directors.”

Dr. McCarthy has servedjoined CytomX in December 2010 as our Chief Business Officer and became a member of our boardBoard, President and Chief Executive Officer in August 2011. In January 2019, Dr. McCarthy became Chairman of our Board of directors and currently serves as Chief Executive Officer and Chairman of our president and chief executive officer since August 2011. Previously,Board. Dr. McCarthy servedhas more than twenty years of experience in the biotechnology industry encompassing roles in R&D, business development, financing and general management. Following completion of his post-doctoral training at the DNAX Research Institute (now Merck Palo Alto), Dr. McCarthy held research leadership and program management roles at Millennium Pharmaceuticals where he managed biologics discovery programs. After Millennium, Dr. McCarthy joined SGX Pharmaceuticals, where he spearheaded a wide range of large pharma partnerships as our chiefvice president business officerdevelopment and helped drive a strategic reorientation of the company from December 2010a platform business model to August 2011. From April 2006product-focused oncology company, leading to December 2010, hecompletion of an initial public offering in 2006. Immediately prior to joining CytomX, Dr. McCarthy was a transactional partner at Pappas Ventures a venture capital firm,from April 2006 to December 2010, where he helped drivewas responsible for investments in therapeutic, medical device and molecular diagnostic companies. Prior to Pappas Ventures, Dr. McCarthy was the vice president of business development at SGX Pharmaceuticals, Inc., where he spearheaded a wide range of strategic collaborations with major pharmaceutical companies, and served on the management team that led to the initial public offering of the company in 2006, before the Company’s ultimate acquisition by Eli Lilly and Company. Prior to SGX Pharmaceuticals, Inc., Dr. McCarthy was associate director of program management at Millennium Pharmaceuticals, Inc., where he managed therapeutic protein programs and a research team that invented novel genomic techniques for the identification of therapeutic proteins. Dr. McCarthy is an author on multiple peer reviewed scientific publications, issued patents and filed patent applications. Dr. McCarthyHe received hisa B.Sc. in biochemistry and pharmacology at King’s College, University of London, his D. Phil.London; an MBA from the Rady School of Management at the University of California San Diego; and a D.Phil. in cancer biology from St. John’s College, University of Oxford and his M.B.A. from the Rady School at the University of California, San Diego.Oxford. Dr. McCarthy currently serves onas a member of the board of directors of the California Life Sciences Association.

Class I Director with TermAssociation and OncoResponse. We believe Dr. McCarthy is qualified to Expireserve on our Board based on his management experience in the life sciences sector, including at CytomX, his deep knowledge of the 2016 Annual Meeting of Stockholders

Elaine V. Jones,industry, and his strategic and business development expertise.

Dr. JonesMohindru has served as a member of our board of directorsBoard since December 2014. Since December 2008, Dr. Jones has served as Executive Director, Venture Capital of Pfizer Venture Investments, the venture capital arm of Pfizer Inc., a global pharmaceutical company. From 2003 to November 2008, Dr. Jones served as a general partner of Euclid SR Partners, a venture capital firm. From 1999 to 2003, Dr. Jones held various positions at S.R. One, the venture fund of GlaxoSmithKline plc, a global pharmaceuticals company. Dr. Jones holds a B.S. in Biology from Juniata College and a Ph.D. in Microbiology from the University of Pittsburgh. Dr. Jones will not stand for re-election at the 2016 Annual Meeting of Stockholders. Dr. Jones has decided not to stand for re-election in order to focus on her other business interests.

Class II Directors Continuing in Office until the 2017 Annual Meeting of Stockholders

Neil Exter

Mr. Exter has served as a member of our board of directors since September 2010. Mr. Exter has been a partner at Third Rock Ventures, a venture capital firm, since November 2007. Prior to joining Third Rock Ventures, Mr. Exter was the chief business officer of Alantos Pharmaceuticals Holding, Inc., leading the sale of the company to Amgen, Inc., and vice president of Millennium Pharmaceuticals, Inc., directing in-licensing and M&A. Earlier in his career, he held various executive management roles within the high technology industry. Mr. Exter2020. She currently serves onas chief executive officer and member of the board of directors at Novasenta, a privately-held drug discovery company that focuses on immunotherapy treatment for novel cancer targets, a position she has held since April 2021. Previously, she served as the CEO of Cibiem,CereXis, Inc., Element Science,a biotech company focused on rare tumor indications, from December 2019 to October 2020. Prior to that, she served as chief financial officer and chief strategy officer at Cara Therapeutics, Inc., a publicly-traded biotechnology company, from August 2017 to December 2019. Between June 2013 and Rhythm Pharmaceuticals. Mr. Exter previously served on the boardAugust 2017 she held various roles at Curis, Inc., a publicly-traded biotechnology company, including vice president of directors of Lotus Tissue Repair (acquired by Shire plc), REVOLUTION Medicines, Inc.corporate strategy & investor strategy and Seventh Sense Biosystems, Inc. Mr. Exterchief strategy officer. Dr. Mohindru is a member of the board research committee at Children’s Hospital Boston and the treasurer andalso a member of the board of directors of the

New England Venture Capital Association. Additionally, Mr. Exter isCardiff Oncology, a member of the Innovation Research Fund at Partners Healthcare and the advisory council of the Electrical and Computer Engineering Department at Cornell University. Mr. Exter received his B.S. from Cornell University, M.S. from Stanford University and M.B.A. as a Baker Scholar from Harvard Business School.

Frederick W. Gluck

Mr. Gluck has served as a member of our board of directors since September 2010 and was a member of the board of directors of CytomX Therapeutics, LLC until September 2010. Mr. Gluckpublicly-traded clinical-stage oncology-focused biopharmaceutical company. She also previously served as a member of the board of directors of Amgen, Inc. from February 1998 to October 2011. He has served asSAb Biotherapeutics, a member and the founding chairmanpublicly-traded clinical-stage biopharmaceutical company advancing a new class of the board of directors of Cynvenio Biosystems, Inc. and TrueVision Systems Inc. since March 2006. Mr. Gluck served as a consultant to McKinsey & Company, Inc., an international management consulting firm (“McKinsey”), from July 1998 to July 2003.immunotherapies. Prior to that, heher leadership roles in the biotechnology industry, Dr. Mohindru spent many years as an equity research analyst covering the biotechnology sector at UBS, Credit Suisse and ThinkEquity. She also cofounded a privately-held biotechnology company and was Vice Chairman

Mr. James R. Meyers has served as a member of our Board since December 2018. Currently, Mr. Meyers serves as the president and CEO of IntraBio, a privately-held biopharmaceutical company with a late-stage drug pipeline that develops treatments for genetic and neurodegenerative diseases, having been appointed to that position in November 2020. Mr. Meyers has served on the board of directorsSangamo Therapeutics, Inc, a publicly-traded biotechnology company, since December 20112019. Prior to that, Mr. Meyers has served as a senior advisor to Gilead Sciences from February 2018 to December 2021. Prior to his advisory role, Mr. Meyers most recently served as Gilead’s executive vice president of worldwide commercial operations where he was responsible for all commercial activities including pricing and market access in North America, Europe, Middle East, Australia and Japan. Over his 22-year career at Gilead, Mr. Meyers led some of the chairmanmost important and successful product launches in the history of our boardthe biopharmaceutical industry, most notably in the therapeutic areas of directors since February 2012. Dr. Huh has been a memberHCV and HIV. Prior to joining Gilead, Mr. Meyers held positions of increasing responsibility in sales, training, marketing and management with Zeneca Pharmaceuticals and Astra USA. Mr. Meyers currently serves on the board of directors of GeronArbutus Biopharma Corporation, since May 2010 and served as its chairman since September 2011. Dr. Huh also is a director of AntriaBio, Inc., apublicly-traded biopharmaceutical company focused on developing novel therapeutic productscommercializing a cure for patients suffering from chronic hepatitis B infection. Mr. Meyers holds a B.S. in Economics from Boston College. We believe that Mr. Meyers is qualified to serve on our Board due to his worldwide commercial leadership experience within the diabetes market. Dr. Huhbiotechnology industry.

Ms. Halley Gilbert has served as a directormember of Addex Pharmaceuticals,our Board since April 2020. Ms. Gilbert had previously served as the chief legal officer of NeoGenomics Laboratories, a pharmaceutical discovery and development company,position she held from May 2011August 2021 to May 2014.2022. Prior to her role at NeoGenomics Laboratories, Ms. Gilbert held the position of chief operating officer of Adagio Therapeutics, Inc., from June 2020 to August 2021. Until February 2020, Ms. Gilbert held the position of senior vice president, corporate development and chief administrative officer at Ironwood Pharmaceuticals, Inc. having joined the company in 2008 as vice president and general counsel. Prior to this, Ms. Gilbert served in several roles at Cubist Pharmaceuticals, Inc. (acquired by Merck), including as vice president, deputy general counsel, assistant secretary and assistant general counsel from 2002 to 2007. From February 20081999 to December 2011, Dr. Huh was2002, Ms. Gilbert held the chairmanposition of corporate counsel at Genzyme Corporation. Ms. Gilbert began her career at the law firm of Skadden, Arps, Slate, Meagher & Flom LLP, where, serving as a corporate associate from 1995 to 1998, she specialized in mergers and acquisitions and securities law. Ms. Gilbert has served on the board of directors of BiPar Sciences,Arcutis Biotherapeutics, Inc. (“BiPar”), a publicly-traded biopharmaceutical company, acquired insince April 2009 by Sanofi-Aventis,2020, and on the board of Vaxcyte, Inc., a global pharmaceutical company. Dr. Huh served as BiPar’s president and chief executive officer from February 2008 to December 2009. Dr. Huh alsopublicly-traded vaccine innovation company, since April 2020. Ms. Gilbert formerly served on the board of directors of Facet Biotech,Dermira, Inc. (acquired by Eli Lilly and Company) and Achaogen, Inc. Ms. Gilbert received a wholly-owned subsidiaryJ.D. from Northwestern University School of Abbott Laboratories,Law and a global, broad-based health care company,B.A. from September 2009Tufts University. We believe that Ms. Gilbert is qualified to April 2010. Dr. Huh was a memberserve on our Board due to her broad knowledge of the board of directors of Nektar Therapeutics (“Nektar”), a clinical-stage biopharmaceutical company, from February 2008 to May 2009,life sciences industry and Nektar’s chief operating

officersignificant experience in business development, corporate strategy, law and senior vice president of Business Development and Marketing from March 2005 to February 2008. Prior to Nektar, compliance.

Dr. Huh was a partner at McKinsey, a global management consulting firm, where he was in the biotechnology and biopharmaceutical sectors. Prior to McKinsey, he held positions as a physician and researcher at Cornell University Medical College and Sloan-Kettering Cancer Center. Dr. Huh holds an A.B. in biochemistry from Dartmouth College and an M.D. and Ph.D. in genetics and cell biology from Cornell University Medical College and Sloan-Kettering Institute.

Timothy M. Shannon, M.D.

Dr. ShannonAlan Ashworth has served as a member of our board of directorsBoard since July 2012. Dr. Shannon has been a Venture Partner at Canaan Partners, a venture capital firm, since November 2009 and a General Partner since January 2015. Dr. ShannonSeptember 2021. He currently serves as a memberthe president of the boardsHelen Diller Family Comprehensive Cancer Center at the University of Arvinas, Inc. (“Arvinas”)California, San Francisco (UCSF), Ideaya Biosciences, Inc., NextCure, Inc., Spyryx Biosciences, Inc. (“Spyryx”), VaxInnate Corporation, and Vivace Therapeutics, Inc. From July 2013 to December 2014, Dr. Shannon serveda position he has held since 2015. He also serves as the senior vice president for cancer services and a

The board of directorsBoard met eight times and acted by unanimous written consent four times during the fiscal year ended December 31, 2015.2022. The Audit Committee of the Board met four times, the Compensation Committee of the Board met nine times and the Nominating and Corporate Governance Committee of the Board met three times. Each member of the board of directors, including Rachel W. Humphrey, M.D., who resigned as a member of the board of directors in August 2015, and Matthew P. Young, who was elected as a member of the board of directors in September 2015,Board attended at least 75 percent75% of the aggregate number of meetings of our board of directorsBoard and of the committees on which he or shethey served, that were held during the period of the last fiscal year forand during which hethey served on the Board or she wassuch committees.

Our Board has a policy of encouraging director or committee member, respectively.

attendance at our annual meetings of stockholders, but attendance is not mandatory. Our Board and management team encourage all of our directors to attend the virtual 2023 Annual Meeting of Stockholders. All of our directors attended the virtual 2022 Annual Meeting of Stockholders.

The board of directorsBoard has documented our governance practices in our corporate governance guidelines to assure that the boardBoard will have the necessary authority and practices in place to review and evaluate our business operations as needed and to make decisions that are independent of our management. The guidelines are also intended to align the interests of directors and management with those of our stockholders. The corporate governance guidelines set forth certain practices the boardBoard will follow with respect to boardBoard composition, boardBoard committees, boardBoard nomination, director qualifications and evaluation of the boardBoard and committees. The corporate governance guidelines and the charter for each committee of the board of directorsBoard may be viewed atwww.cytomx.com.

www.cytomx.com.

Our bylaws and Corporate Governance Guidelines provide our Board with flexibility to combine or separate the positions of chairman of the Board and chief executive officer and/or the implementation of a lead director in accordance with its determination that utilizing one or the other structure would be in the best interests of the Company. The positionsposition of chief executive officer and chairman of the board of directors areBoard is currently held by Sean A. McCarthy, D. Phil. The Board also appointed Matthew P. Young to serve as Lead Independent Director of the Board. In that role, Mr. Young presides over the executive sessions of the Board in which Dr. McCarthy does not participate, serves as a liaison to Dr. McCarthy and Hoyoung Huh, M.D., Ph.D., respectively. The boardmanagement on behalf of directors believesthe Board and performs such other duties and exercises such other powers as may from time to time be assigned by the bylaws or the Board.

Our Board has concluded that our current leadership structure is appropriate at this time having a separate chairman provides a more effective channel fortime. However, our Board will continue to periodically review our leadership structure and may make such changes in the board of directors to express its views on management, by enhancing the board’s oversight of, and independence from, management, and allows the chief executive officer to focus more on the strategy and operations of the Company.

future as it deems appropriate.

The board of directorsBoard monitors and assesses key business risks directly through deliberations of the board of directorsBoard and also by way of delegation of certain risk oversight functions to be performed by committees of the board of directors.Board. The board of directorsBoard regularly reviews and assesses, among other matters, the following important areas that present both opportunities and risk to the Company’s business:

The discussion above of risk oversight matters reviewed by the board of directorsBoard is intended to be illustrative only and not a complete list of all important matters reviewed and considered by the board of directorsBoard in providing oversight and direction for the Company’s senior management and business.

The risk oversight function of the board of directorsBoard is also administered through various boardBoard committees. The audit committeeAudit Committee oversees the management of financial, accounting, internal controls, disclosure controls, and the engagement arrangement and regular oversight of the independent auditors.auditors and other financial compliance risks. The audit committeeAudit Committee also periodically reviews the Company’s investment policy for its cash reserves and fraud monitoring practices and procedures, including the maintenance and monitoring of a whistleblower hotline.

The compensation committeeCompensation Committee is responsible for the design and oversight of the Company’s compensation programs. The compensation committeeCompensation Committee also regularly reviews and reports to the board of directorsBoard on succession planning for the chief executive officer and certain other select senior management positions.

The nominatingNominating and corporate governance committeeCorporate Governance Committee periodically reviews the Company’s corporate governance practices, including certain risks that those practices are intended to address.address and certain corporate compliance risks. The nominatingNominating and corporate governance committeeCorporate Governance Committee periodically reviews the composition of the board of directorsBoard to help ensure that a diversity of skills and experiences is represented by the members of the board of directorsBoard taking into account the stage of growth of the Company and its strategic direction.

direction, as well as identifies, evaluates and nominates qualified candidates.

In carrying out their risk oversight functions, the board of directorsBoard and its committees routinely request and review management updates, reports from the independent auditors and legal and regulatory advice from outside experts, as appropriate, to assist in discerning and managing important risks that may be faced by the Company. The board of directorsBoard is committed to continuing to ensure and evolve its risk oversight practices as appropriate given the stage of the Company’s evolution as a drug development Company and the fast-paced changes in the biopharmaceutical industry.

Under the rules of The NASDAQNasdaq Stock Market LLC (“NASDAQ”Nasdaq”), independent directors must comprise a majority of a listed company’s board of directors within twelve months from the date of listing. In addition, NASDAQNasdaq rules require that, subject to specified exceptions, each member of a listed company’s audit, compensation and nominating and corporate governance committees be independent. Audit committee members must also satisfy additional independence criteria set forth in Rule 10A-3 under the Exchange Act, and in NASDAQ ruleNasdaq Rule 5605(c)(2)(A). Under NASDAQNasdaq rules, a director will only qualify as an “independent director” if, in the opinion of that company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director.

Our board of directorsBoard has undertaken a review of its composition, the composition of its committees and the independence of each director. Based upon information requested from and provided by each director concerning his or hertheir background, employment and affiliations, including family relationships, our board of directorsBoard determined that none of our directors, other than Dr. McCarthy, has a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and that each of these directors is “independent���“independent” as that term is defined under the NASDAQNasdaq rules. Dr. McCarthy is not considered independent because he is an employee of the Company. Our board of directorsBoard determined that Neil Exter and Frederick W. Gluck, members of our audit committee and compensation committee, Matthew P. Young, a member of our audit committee and nominating and corporate governance committee, Timothy M. Shannon, M.D.,Audit Committee, James R. Meyers, a member of our compensation committee, and Hoyoung Huh, M.D.,Compensation Committee, Elaine V. Jones, Ph.D., a member of our nominatingCompensation Committee and corporate governance committee,Nominating and Corporate Governance Committee, Halley Gilbert, a member of our Audit Committee and Nominating and Corporate Governance Committee, Mani Mohindru, Ph.D., a member of our Compensation Committee and Audit Committee, and Alan Ashworth, Ph.D., a member of our Nominating and Corporate Governance Committee, satisfy the independence standards for such committees established by applicable SEC and the NASDAQNasdaq rules, including, with respect to Mr. GluckMs. Gilbert, Dr. Mohindru and Mr. Young, the heightened independence criteria applicable to the audit committee,Audit Committee, as set forth in Rule 10A-3 and NASDAQNasdaq Rule 5605. Mr. Exter, a member of our audit committee, does not meet the heightened independence criteria set forth in Rule 10A-3 and NASDAQ Rule 5605 since Third Rock Ventures, L.P. continues to own more than ten percent of our capital stock as of March 31, 2016. We intend to satisfy the audit committee independence requirements of the listing standards of NASDAQ within the one-year transition period provided by Rule 10A-3 and the NASDAQ rules. In making these determinations, our board of directorsBoard considered the relationships that each non-employee director has with us and all other facts and circumstances our board of directorsBoard deemed relevant in determining their independence, including the beneficial ownership of our capital stock by each non-employee director.

Our Board has three regularly constituted committees: an audit committee,Audit Committee, a compensation committeeCompensation Committee and a nominatingNominating and corporate governance committee.Corporate Governance Committee. The following table provides current membership and meeting information as of December 31, 2015 for each of the boardBoard committees:

Name		Audit		Compensation		Nominating and Corporate Governance
Sean A. McCarthy, D. Phil.		—		—		—
Neil Exter		X		X		—
Frederick W. Gluck		X		X		—
Hoyoung Huh, M.D., Ph.D.		—		—		X(1)
Elaine V. Jones, Ph.D.(2)		—		—		—
Timothy M. Shannon, M.D.		—		X(1)		—
Matthew P. Young		X(1)		—		X
Rachel W. Humphrey, M.D.(3)		—		—		—
Total meetings in 2015		4		4		0

The audit committeeAudit Committee of the board of directorsBoard oversees our corporate accounting and financial reporting process. For this purpose, the audit committeeAudit Committee performs several functions. The responsibilities of the audit committeeAudit Committee include, among other things:

The audit committeeAudit Committee has the power to investigate any matter brought to its attention within the scope of its duties and will have the authority to retain counsel and advisors to fulfill its responsibilities and duties.

The audit committeeAudit Committee has the authority to retain special legal, accounting or other consultants to advise the committee as it deems necessary, at the Company’s expense, to carry out its duties and to determine the compensation of any such advisors.

The members of the audit committeeAudit Committee are Matthew P. Young, Neil ExterMani Mohindru, Ph.D. and Frederick W. Gluck.Halley Gilbert. Mr. Young serves as the chairperson of the committee. Our board of directorsBoard has determined that each of Mr. Young, Dr. Mohindru and Mr. GluckMs. Gilbert are “independent” for audit committeeAudit Committee purposes as that term is defined in the applicable rules of the SEC and The NASDAQNasdaq Global Select Market. Mr. Exter is a partner of Third Rock Ventures but does not have voting or investment power over any of the shares purchased by Third Rock Ventures, L.P. Since Third Rock Ventures, L.P. continues to own more than ten percent of our capital stock as of March 31, 2016, Mr. Exter does not meet the heightened independence criteria set forth in Rule 10A-3 and NASDAQ Rule 5605. We intend to satisfy the audit committee independence requirements of the listing standards of NASDAQ within the one-year transition period provided by Rule 10A-3 and the NASDAQ rules. Our board of directorsBoard has designated Mr. Young as an “audit committee financial expert” as defined under the applicable rules of the SEC.SEC and has determined that Mr. Young has the requisite financial sophistication as defined under the applicable rules and regulations of Nasdaq. The audit committeeAudit Committee has adopted a written audit committeeAudit Committee charter that satisfies the applicable standards of the SEC and Nasdaq, and which is available on our corporate website atwww.cytomx.com.

www.cytomx.com.

The compensation committeeCompensation Committee of the board of directorsBoard reviews the type and level of compensation for directors, officers, employees and compensation consultants of the Company, recommends compensation actions to the board of directorsBoard and administers the variable compensation programs to be adopted by the Company. The responsibilities of the compensation committeeCompensation Committee include, among other things:

The compensation committeeCompensation Committee has the power to investigate any matter brought to its attention within the scope of its duties and will have the authority to retain counsel and advisors to fulfill its responsibilities and duties.

The compensation committeeCompensation Committee has the sole authority to retain or replace, at the Company’s expense, any independent counsel, compensation and benefits consultants and other outside experts or advisors as the committee

The members of the compensation committeeCompensation Committee are Timothy M. Shannon, M.D., Neil ExterJames Meyers, Elaine V. Jones, Ph.D. and Frederick W. Gluck. Dr. ShannonMani Mohindru, Ph.D. Mr. Meyers serves as the chairperson of the committee. Our board of directorsBoard has determined that each member of the compensation committeeCompensation Committee is an independent director for compensation committeeCompensation Committee purposes as that term is defined in the applicable NASDAQNasdaq rules, and is a “non-employee director” within the meaning of Rule 16b-3(d)(3) promulgated under the Exchange Act and is an “outside director” within the meaning of Section 162(m) of the Internal Revenue Code of 1986, as amended.Act. The compensation committeeCompensation Committee has adopted a written audit committeeCompensation Committee charter that satisfies the applicable standards of the SEC and Nasdaq, and which is available on our corporate website atwww.cytomx.com.