You are cordially invited to attend the 20162024 Annual Meeting of Stockholders of CytomX Therapeutics, Inc., a Delaware corporation.corporation (the “Company” or “CytomX”). The 20162024 Annual Meeting of Stockholders will be held on June 10, 2016,May 15, 2024, at 31:00 p.m., Pacific Time, atTime. The 2024 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, for2024 Annual Meeting of Stockholders by visiting www.virtualshareholdermeeting.com/CTMX2024, 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 20162024 Annual Meeting of Stockholders is April 12, 2016.March 19, 2024. Only stockholders of record at the close of business on that date are entitled to notice of, and to vote at, the 20162024 Annual Meeting of Stockholders or any adjournment thereof.

Your vote is very important. Whether or not you attend the 20162024 Annual Meeting of Stockholders in person,(by logging into www.virtualshareholdermeeting.com/CTMX2024), 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, 2023, and submit your proxy on the Internet, by phone or by mail in accordance with the instructions

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 20162024 Annual Meeting of Stockholders to be held on June 10, 2016May 15, 2024 at 31:00 p.m., Pacific Time,Time. The meeting will be held virtually, via a live webcast at www.virtualshareholdermeeting.com/CTMX2024. 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, 2023 (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 March 19, 2024 (the “Record Date”) for the first time on or about April 28, 20164, 2024. The Notice of Internet Availability will contain instructions on how to all stockholdersaccess and review the 2024 Annual Meeting materials, how to access the live webcast of the 2024 Annual Meeting of Stockholders, and will also contain instructions on how to request a printed copy of the 2024 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, 2016March 19, 2024 will be entitled to vote at the annual meeting. On this record date,Record Date, there were 36,085,80967,731,764 shares of common stock outstanding and entitled to vote.

If, on April 12, 2016,March 19, 2024, 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/CTMX2024, 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,March 19, 2024, 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.

Under rules adopted by the Securities and Exchange Commission (“SEC”),SEC, we are sending the notice to our stockholders of record and beneficial owners as of April 12, 2016.March 19, 2024. Stockholders will have the ability to access the proxy materials, including this proxy statementProxy Statement and our Annual Report on Form 10-K for the fiscal year ended December 31, 2015,2023, on the Internet atwww.proxyvote.com or to request a printed or electronic set of the proxy materials at no charge. Instructions on how to access the proxy materials over the Internet and how to request a printed copy may be found on the notice.

In addition, any stockholder may request to receive proxy materials in printed form by mail or electronically by email on an ongoing basis. Choosing to receive future proxy materials by email will save us the cost of printing and mailing documents to stockholders and will reduce the impact of annual meetings on the environment. A stockholder who chooses to receive future proxy materials by email will receive an email prior to next year’s annual meeting with instructions containing a link to those materials and a link to the proxy voting website. A stockholder’s election to receive proxy materials by email will remain in effect until the stockholder terminates it.

If you are a stockholder of record as of April 12, 2016,March 19, 2024, you may vote in person atby attending the annual meeting online at www.virtualshareholdermeeting.com/CTMX2024 and following the instructions posted on the webcast portal. You may also vote by proxy over the Internet or by phone by following the instructions provided in the noticeNotice of Access of Internet Availability of Proxy Materials or, if you request printed copies of the proxy materials by mail, you may vote by mail. If your proxy is properly executed in time to be voted at the annual meeting, the shares represented by the proxy will be voted in accordance with the instructions you provide. Whether or not you plan to attend the annual meeting online, we urge you to vote by proxy to ensure your vote is counted. You may still attend the annual meeting online and vote in persononline at www.virtualshareholdermeeting.com/CTMX2024 if you have already voted by proxy.proxy, so long as you do so before voting closes.

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.

On each matter to be voted upon, you have one vote for each share of common stock you owned as of April 12, 2016.

March 19, 2024.

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,March 19, 2024, there were 36,085,80967,731,764 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 you are a beneficial owner of shares registered in the name of your broker, bank or other agent, your shares are held by your broker, bank or other agent as your nominee, or in “street name,” and you will need to obtain a proxy form from the organization that holds your shares and follow the instructions included on that form regarding how to instruct the organization to vote your shares. If you do not give instructions to your broker, bank or other agent, itthey can vote your shares with respect to “discretionary” items but not with respect to “non-discretionary” items. Discretionary items are proposals considered routine under the rules of various national securities exchanges, and, in the absence of your voting instructions, your broker, bank or other agent may vote your shares held in street name on such proposals. Non-discretionary items are proposals considered non-routine under the rules of various national securities exchanges, and, in the absence of your voting instructions, your broker, bank or other agent may not vote your shares held in street name on such proposals and the shares will be treated as broker non-votes. Proposals

Proposal 1 3(the election of directors) and Proposal 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.4. 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, 2024) and Proposal 3 (amendment of our Amended and Restated Certificate of Incorporation) are 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.

Proposals 2 and 3.

We will pay for the entire cost of soliciting proxies. We have retained Georgeson LLC to assist in the solicitation of proxies for a fee of approximately $15,000 plus associated costs and expenses. 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/CTMX2024 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 2025 Annual Meeting of Stockholders. Any such proposal must be submitted in writing by December 29, 2016,5, 2024, to our Secretary, care of CytomX Therapeutics, Inc., at 343 Oyster Point Blvd., Suite 100, South San Francisco, CA 94080, our current principal executive offices address, if such proposal is submitted to us before December 1, 2016, or 151 Oyster Point Boulevard, Suite 400, South San Francisco, CA 94080, the address of our new principal executive offices address, if such proposal is submitted to us on or after December 1, 2016, the date around which we currently expect to move into the new offices. If we change the date of our 20172025 Annual Meeting of Stockholders by more than 30 days from the date of the previous year’s annual meeting,2024 Annual Meeting of Stockholders, the deadline shall be a reasonable time before we begin to print and send our proxy materials. Stockholders interested in submitting such a proposal are advised to contact knowledgeable counsel with regard to the detailed requirements of the applicable securities laws and our bylaws. The submission of a stockholder proposal does not guarantee that it will be included in our proxy statement.

Our bylaws also establish an advance notice procedure for stockholders who wish to present a proposal before an annual meeting of stockholders but do not intend for the proposal to be included in our proxy statement. Our bylaws provide that if you wish to submit a proposal that is not to be included in next year’s proxy statement or nominate a director, a timely written notice of a stockholder proposal must be delivered to, or mailed and received by, our Secretary, care of CytomX Therapeutics, Inc., at 151 Oyster Point Boulevard, Suite 400, South San Francisco, CA 94080, no earlier than February 10, 2017January 15, 2025 and no later than the close of business on March 13, 2017,February 14, 2025, which notice must contain the information specified in our bylaws. If we change the date of our 20172025 Annual Meeting of Stockholders by more than 30 days before, or more than 60 days after, the one-year

anniversary of the 20162024 Annual Meeting of Stockholders, then the written notice of a stockholder proposal that is not intended to be included in our proxy statement must be delivered, or mailed and received, not later than the 90^th90th day prior to our 20172025 Annual Meeting of Stockholders or, if later, the 10^th10th day following the day on which certain public disclosure as described in our bylaws of the meeting date is made.

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.

If you are a beneficial owner of our common stock, once you receive notice from your broker, bank or other agent that they will be householding communications to your address, householding will continue until you are

Preliminary voting results will be announced atduring the live webcast of the annual meeting. Final voting results will be published in a Current Report on Form 8-K filed with the SEC within four business days following the annual meeting.

Our board of directorsBoard currently consists of seveneight 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 twothree directors in Class I, Sean A. McCarthy, D. Phil.III, Alan Ashworth, Ph.D., FRS, James R. Meyers and Elaine V. Jones, Ph.D.,Halley Gilbert, whose termterms of office expires upon the election of directorsare scheduled to expire at the 20162024 Annual Meeting of Stockholders. Each of Dr. McCarthy, one of the current directors in Class I, hasAlan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert have been nominated for election at the 20162024 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 Dr. McCarthy becomesAlan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert 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. Dr. McCarthy hasAlan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert have agreed to serve if elected. Our management has no reason to believe that any of Dr. McCarthyAlan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert will be unable to serve. If elected at the annual meeting, each of Dr. McCarthyAlan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert will serve until the earliest of the 20192027 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 Dr. McCarthy,Alan Ashworth, Mr. James R. Meyers and Ms. Halley Gilbert, 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 Dr. McCarthy as a nomineeAshworth, Mr. Meyers and Ms. Gilbert for director, as of the date of this proxy statement.

Dr. McCarthyAlan Ashworth has served as a member of our board of directors and our president and chief executive officerBoard since August 2011. Previously, Dr. McCarthy servedSeptember 2021. He currently serves as our chief business officer from December 2010 to August 2011. From April 2006 to December 2010, he was a transactional partner at Pappas Ventures, a venture capital firm, where he helped drive 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 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 SchoolHelen Diller Family Comprehensive Cancer Center at the University of California, San Diego.Francisco (UCSF), a position he has held since 2015. He also serves as the senior vice president for cancer services and a Professor of Medicine in Division of Hematology/Oncology, Department of Medicine at UCSF Health, position(s) he has held since 2015. Prior to joining UCSF, Dr. McCarthyAshworth was chief executive officer of the Institute of Cancer Research, a position he held from 2011 to 2014, as well as serving as their director of the Breakthrough Breast Cancer Center from 1999 to 2011 and Professor of Molecular Biology from 1997 to 2014. He is an elected member of European Molecular Biology Organization, the Academy of Medical Sciences, and a Fellow of the Royal Society. Dr. Ashworth received his Ph.D. in biochemistry from University College London, U.K., and his B.Sc. in chemistry and biochemistry from Imperial College of Science and Technology, University of London, U.K. We believe that Dr. Ashworth is qualified to serve on our Board due to his deep medical experience and service on the boards of directors of several cancer centers.

Ms. Halley Gilbert has served as a member of our Board since April 2020. Currently, Ms. Gilbert serves as the Chief Legal Officer of CARGO Therapeutics, a publicly-traded biotechnology company, a position she has held since September 2023. Ms. Gilbert had previously served as the chief legal officer of NeoGenomics Laboratories, a position she held from August 2021 to April 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 1999 to 2002, Ms. Gilbert held the position 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.

Arcutis Biotherapeutics, Inc., a publicly-traded biopharmaceutical company, since April 2020, and on the board of Vaxcyte, Inc., a publicly-traded vaccine innovation company, since April 2020. Ms. Gilbert formerly served on the board of directors of Dermira, Inc. (acquired by Eli Lilly and Company) and Achaogen, Inc. Ms. Gilbert received a J.D. from Northwestern University School of Law and a B.A. from Tufts University. We believe that Ms. Gilbert is qualified to serve on our Board due to her broad knowledge of the life sciences industry and significant experience in business development, corporate strategy, law and compliance.

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, 20162024, 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, 2016.2024. Abstentions will not be counted as votes cast on this proposal. No broker non-votes are expected to exist in connection with this proposal.

Presently, our Amended and Restated Certificate of Incorporation authorizes the annual meeting, our stockholders will be asked to approve the CytomX Therapeutics, Inc. Annual Incentive Plan (the “Bonus Plan”) under which officers and other employeesissuance of 150,000,000 shares of common stock, par value $0.00001 per share. As of March 19, 2024, the Company would be eligible to receive incentive payments based onhad 67,731,764 shares of common stock issued and outstanding. Also, as of December 31, 2023, 5,609,599 shares of common stock were reserved for issuance under our equity compensation plans. In total, 76,658,637 shares of authorized common stock remain available for issuance.

In December 2023, 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 intendedBoard determined 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 that 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 participateincrease in the Bonus Plan for a specified performance period commencing after June 10, 2016 (a “Performance Period”) by providing such designated officersnumber of shares of common stock was advisable and employees within 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 employeesbest interest of the Company and its subsidiaries are eligiblestockholders and unanimously approved an amendment to be designated as participants inArticle Four of our Amended and Restated Certificate of Incorporation to increase 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 beginningauthorized number of shares of common stock from 150,000,000 to 3000,000,000 shares, subject to stockholder approval 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 performance in 2015.

amendment.

The affirmative vote of the holders of a majority of the shares of our common stock present in personvotes cast either online or represented by proxy at the annual meeting and castthat are entitled to vote on thisthe proposal will be required to approve the CytomX Therapeutics, Inc. Annual Incentive Plan. Abstentionsamendment of our Amended and broker non-votes will not be counted asRestated Certificate of Incorporation, with votes cast on this proposal.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE IN FAVOR OF PROPOSAL 3.

PROPOSAL 4

APPROVAL OF THE PERFORMANCE MEASURES INCLUDED IN THE CYTOMX THERAPEUTICS, INC. 2015 EQUITY INCENTIVE PLAN

At the annual meeting, our stockholdersincluding votes “Against” and excluding abstentions. This is a routine proposal and therefore we do not expect any broker non-votes.

Any additional authorized shares of common stock will be askedidentical to approve the material termsshares of the performance measures used for performance-based awards granted under the CytomX Therapeutics, Inc. 2015 Equity Incentive Plan (the “2015 Plan”), in accordance with Section 162(m) of the Code.common stock now authorized and outstanding. The 2015 Plan was approved by the board of directors on September 17, 2015, and by our stockholders on October 2, 2015. Stockholders are being asked to approve the performance measures under the 2015 Plan so that certain compensation paid under the 2015 Plan may qualify as performance-based compensation under Section 162(m), assuming other applicable conditions are satisfied. Stockholders are not being asked to approve anproposed increase in the number of shares available underof common stock will not change the 2015 Plan or any amendment to the 2015 Plan.

As discussed in Proposal 3, Section 162(m) limits the deduction for federal income tax purposes of compensation for 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 that the compensation must be paid based upon the attainment of performance measures established by a committee of board members meeting the definition of “outside director” used for purposes of Section 162(m). In addition, the performance measures established by such a committee, which in our case would be the compensation committee, must be based upon performance measures, the material terms of which are approved by stockholders. Following our IPO, that stockholder approval must be obtained no later than the first regularly scheduled meeting of stockholders that occurs after the close of the third calendar year following the calendar year in which the Company became a publicly-held corporation.

We are accordingly requesting the stockholders to approve the material terms of the performance measures for the 2015 Plan in accordance with Section 162(m).

The following is a description of the material terms of the performance measures and certain other material terms of the 2015 Plan. This description is qualified in its entirety by reference to the 2015 Plan, a copy of which has been included as Appendix B to this proxy statement.

Material Terms of the Performance Measures

Eligible Participants

All officers, non-employee directors, employees, consultants, agents and independent contractors, and persons expected to become officers, non-employee directors, employees, consultants, agents and independent contractors of the Company or any of our subsidiaries are eligible to receive awards under the 2015 Plan. The compensation committee of our board will determine the participants under the 2015 Plan. As of April 12, 2016, approximately five executive officers, 60 other employees and seven non-employee directors were eligible to participate in the 2015 Plan.

Award Limits

To the extent necessary for an award to be qualified performance—based compensation under Section 162(m), (i) the maximum number of shares of Companystock outstanding, have any immediate dilutive effect or change the rights of current holders of our common stock. However, to the extent that the additional authorized shares of common stock with respectare issued in the future, they may decrease existing stockholders’ percentage equity ownership and, depending on the price at which they are issued, could be dilutive to the voting rights of existing stockholders and may dilute earnings and book value on a per share basis. Stockholders do not have preemptive rights to acquire the common stock authorized by this amendment, which options and share appreciation rights,means that current stockholders do not have a prior right to purchase any new issue of capital stock in order to maintain their proportionate ownership of our common stock.

In addition to dilution, the availability of additional shares of common stock for issuance could, under certain circumstances, discourage or a combination thereof, may be granted duringmake more difficult any fiscal yearefforts to obtain control of us. The Board is not aware of any actual or contemplated attempt to acquire control of the Company and this proposal is not being presented with the intent that it be used to prevent or discourage any personacquisition attempt. However, nothing would prevent the Board from taking any actions that it deems consistent with its fiduciary duties.

If the proposed amendment to increase the number of authorized shares of common stock is approved by our stockholders, the amendment will become effective immediately upon the filing of a Certificate of Amendment to our Amended and Restated Certificate of Incorporation with respectthe Secretary of State of the State of Delaware, which we expect to which restricted shares or restricted share units subject to performance measures or performance units denominated infile promptly after the annual meeting. If the proposed amendment is not approved by our stockholders, the number of authorized shares of CompanyCommon Stock will remain unchanged.

The Board believes that additional authorized shares of common stock that may be granted during any fiscal year ofwould give the Company the necessary flexibility to issue shares for various corporate purposes, including, in particular, capital-raising or financing

Because our cash flow from operations has been negative, if the ratios specifically enumerated above, performance goals may include comparisons relating to capital (including, butstockholders do not limited to,approve this proposal, the cost of capital), stockholders’ equity, shares outstanding, assets or net assets, or any combination thereof. The applicable performance measuresBoard may be applied onprecluded from pursuing a pre-wide range of potential corporate opportunities that might raise necessary cash or post-tax basis and mayotherwise be adjusted in accordance with Section 162(m) 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 162(m) covered employees and who are not expected to be 162(m) covered employees at any time during the applicable performance period, the performance goals may include any objective or subjective corporate-wide or subsidiary, division, operating unit or individual measures, whether or not listed above.

Summary Description of the 2015 Plan

Under the 2015 Plan, the Company may grant: nonqualified options; incentive stock options; share appreciation rights; bonus shares; restricted shares; restricted share units; and performance units. The purposes of the 2015 Plan are (i) to align the interests of the Company’s stockholders and the recipients of awards under the 2015 Plan by increasing the proprietary interest of such recipients in the Company’s growth and success, (ii) to advance the interests of the Company by attracting and retaining non-employee directors, officers, employees and other service providers and (iii) to motivate such persons to act in the long-term best interests of the Company and itsthe best interests of our stockholders.

Administration

The compensation committee will interpret, construe This could have a material adverse effect on our business and administer the 2015 Plan. The compensation committee’s interpretation, constructionprospects. We would also face substantial challenges in hiring and administration of the 2015 Plan andretaining employees at all of its determinations thereunder will be final, conclusive and binding on all persons. The compensation committee will have the authority to determine the participantslevels, including our executive leadership team, in the 2015 Plan, the form, amount and timing of any awards, the performance goals, if any, and all other terms and conditions pertaining to any award. The compensation committee may take any action such that (i) any outstanding options and share appreciation rights become exercisable in part or in full, (ii) all or any portion of a restriction period on any restricted shares or restricted share units will lapse, (iii) all or a portion of any performance period applicable to any outstanding award will lapse and (iv) any performance measures applicable to any outstanding award will be deemed satisfied at the target level or any other level.

The compensation committee may delegate some or all of its powers and authority to the board of directors, the chief executive officer and president or other executive officer as the compensation committee deems appropriate, subject to Section 162(m) and Section 16 of the Exchange Act, except that the compensation committee may not delegate its responsibilities with respect to awards granted to 162(m) covered employees.

Available Shares

The 2015 Plan initially reserved 2,444,735 shares of common stock for issuance of awards under the 2015 Plan, subject to adjustment for stock splits and other similar changes in capitalization. The number of available shares will be reduced by the aggregate number of shares that become subject to outstanding awards granted under the 2015 Plan. As of the first day of each calendar year beginning on or after January 1, 2016, the number of shares available for all awards under the 2015 Plan, other than incentive stock options, will automatically increase by 4% of the number of shares that are issued and outstanding as of that date, unless the compensation committee approves an increase of a lesser percentage. To the extent that shares subject to an outstanding award granted under the 2015 Plan are not issued or delivered by reason of the expiration, termination, cancellation or forfeiture of such award or by reason of the settlement of an award in cash, then those shares will again be available under the 2015 Plan. Shares subject to an award under the 2015 Plan may not be made available for issuance under the 2015 Plan if such shares are: (i) shares that were subject to a share-settled share appreciation right and were not issued upon the net settlement or net exercise of such share appreciation right, (ii) shares used to pay the exercise price of an option, (iii) shares delivered to or withheld by the Company to pay withholding taxes related to an award under the 2015 Plan, or (iv) shares repurchased on the open market with the proceeds of an option exercise. On April 12, 2016, the closing sales price per share of Company common stock as reported on The NASDAQ Global Select Market was $13.15.

Effective Date, Termination and Amendment

The 2015 Plan became effective on October 6, 2015 and will terminate on the September 17, 2025, unless earlier terminated by the board of directors. The board of directors may amend the 2015 Plan at any time, subject to stockholder approval if required by applicable law, rule or regulation, including Section 162(m), or any rule of the NASDAQ. No amendment may materially impair the rights of a holder of an outstanding award without the consent of such holder.

Change in Control

In the event of a change in control, the board of directors may, in its discretion, (i) provide that (a) some or all outstanding options and share appreciation rights will immediately become exercisable in full or in part, (b) the restriction period applicable to some or all outstanding share awards will lapse in full or in part, (c) the performance period applicable to some or all outstanding awards will lapse in full or in part, and (d) the performance measures applicable to some or all outstanding awards will be deemed to be satisfied at the target or

any other level, (ii) require that shares of stock of the Company resulting from such change in control, or a parent

corporation thereof, be substituted for some or all of our shares subject to an outstanding award, and/or (iii) require outstanding awards, in whole or in part, to be surrendered by the holder, and to be immediately cancelled, and to provide for the holder to receive (a) a cash payment in an amount equal to (1) in the case of an option or share appreciation right, the number of our shares then subject to the portion of such option or share appreciation right surrendered, whether vested or unvested, multiplied by the excess, if any, of the fair market value of a share of our common stock as of the date of the change in control, over the purchase price or base price per share of our common stock subject to such option or share appreciation right, (2) in the case of a share award, the number of shares of our common stock then subject to the portion of such award surrendered, whether vested or unvested, multiplied by the fair market value of a share of our common stock as of the date of the change in control, and (3) in the case of a performance unit award, the value of the performance units then subject to the portion of such award surrendered, whether vested or unvested; (b) shares of capital stock of the Company resulting from such change in control, or a parent corporation thereof, having a fair market value not less than the amounts determined under clause (iii)(a) above; or (c) a combination of the payment of cash pursuant to clause (iii)(a) above and the issuance of shares pursuant to clause (iii)(b) above.

Under the 2015 Plan, a change in control is generally defined as: (i) a person’s or entity’s acquisition, other than from us, of beneficial ownership of 50% or more of either our then outstanding shares or the combined voting power of our then outstanding voting securities, but excluding certain acquisitions by the Company, its subsidiaries or employee benefit plans, or by a corporation in which our shareholders hold a majority interest; (ii) a reorganization, merger or consolidation of the Company if our shareholders do not thereafter beneficially own more than 50% of the outstanding shares or combined voting power of the resulting company; (iii) an unapproved change in the composition of a majority of our board; or (iv) a complete liquidation or dissolution of the Company or of the sale or other disposition of all or substantially all of our assets; but excluding, in any case, the initial public offering or any bona fide primary or secondary public offering following the occurrence of the initial public offering.

Tax Matters

In general, a participant will not recognize taxable income at the time an option is granted. Upon exercise of a non-qualified option, a participant will recognize compensation, taxable as ordinary income, equal to the excess of the fair market value of the shares of common stock purchased over their exercise price. In the case of “incentive stock options,” within the meaning of Section 422 of the Code, a participant will not recognize ordinary income at the time of exercise (except for purposes of the alternative minimum tax), and if the participant observes certain holding period requirements, then when the shares are sold, the entire gain over the exercise price will be taxable at capital gains rates. If the participant does not observe the holding period requirements, then when the shares are sold, the participant generally will recognize compensation, taxable as ordinary income, equal to the excess of the fair market value of the shares at the time of exercise (or, if less, the amount realized on the sale of the shares) over the exercise price. A participant has no taxable income at the time share appreciation rights are granted, but will recognize compensation taxable as ordinary income upon exercise in an amount equal to the fair market value of any shares of common stock delivered and the amount of any cash paid by the Company. A participant who is granted restricted shares, including shares subject to performance conditions, generally will not recognize taxable income at the time the restricted shares are granted, but will recognize compensation taxable as ordinary income at the time the restrictions constituting a substantial risk of forfeiture lapse in an amount equal to the excess of the fair market value of the shares of common stock at such time over the amount, if any, paid for such shares. However, a participant instead may elect to recognize compensation taxable as ordinary income on the date the restricted shares are granted in an amount equal to the fair market value of the shares on that date over the amount, if any, paid for such shares. If such election is made, any subsequent gain upon disposition of the shares will be taxable at capital gains rates. The taxation of other share-based awards will depend on how such awards are structured. Generally, a participant who is granted an award of restricted share units, including restricted share units subject to performance conditions, or some other performance unit will not recognize taxable income at the time such award is granted. When the restrictions applicable to the award lapse, and the shares of common stock subject to the restricted share units or other award

are transferred (or any amount of cash is paid) to the participant, the participant will recognize compensation taxable as ordinary income in an amount equal to the fair market value of the shares of common stock on the date of transfer and the amount of any cash paid by the Company.

Subject to the Section 162(m) deduction limitation described above, the Company may deduct, as a compensation expense, the amount of ordinary income recognized by a participant in connection with the 2015 Plan at the time such ordinary income is recognized by that participant.

New Plan Benefits

The number of performance-based awards granted under the 2015 Plan in any year is subject to the compensation committee’s discretion and is, therefore, not determinable.

The affirmative 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 performance measures included in the CytomX Therapeutics, Inc. 2015 Equity Incentive Plan. Abstentions and broker non-votes will not be counted as votes cast on this proposal.

near term.

The following table sets forth certain information regarding the ownership of our common stock as of March 31, 2016,19, 2024, 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 March 19, 2024, there were 67,731,764 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, 2015,2023, all filing requirements applicable to our executive officers and directors under the Exchange Act were met in a timely manner other than a late Form 4 for Marcia Belvin filed on March 29, 2023 due to administrative delays.

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, 2015Proxy Statement.

In July 2023, we completed a private placement transaction (the “IPO”“2023 PIPE Financing”), 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 stockpursuant 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,which we issued and sold an aggregate of 941,842 shares of our Series C preferred stock at a(i) pre-funded warrants to purchase price of $5.309387 per share for an aggregate purchase price of approximately $5.0 million in cash, including (i) 659,209 shares issuedup 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 their14,423,077 shares of our common stock, or request that their(ii) Tranche 1 Warrants to purchase up to 5,769,231 shares of our common stock be covered(or pre-funded warrants in lieu thereof) and (iii) Tranche 2 Warrants to purchase up to 5,769,231 shares of our common stock (or pre-funded warrants in lieu thereof). The combined price per pre-funded warrant and accompanying tranche warrant is $2.08 (of which $2.07999 per share was prepaid by each purchaser). As a result of the 2023 PIPE Financing, we received aggregate net proceeds of approximately $29.7 million after deducting offering expenses payable by us. In connection with the 2023 PIPE Financing, on August 16, 2023, we filed a registration statement that we are otherwise filing, including, in each case,on Form S-3 with the SEC registering the resale of all 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 tomay 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 required2023 PIPE Financing.

Immediately prior 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,2023 PIPE Financing, certain entities affiliated with BVF Partners L.P. were the registration rightsbeneficial owners of, a holder of registrable securities will expire if all ofin 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 ownsaggregate, more than five percent5% of our capital stock. In May 2013, we entered intoconnection with the 2023 PIPE

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 20162024 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 2016this 2024 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 has2020. Most recently she 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 Collegechief executive officer 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. Exter currently serves on the board of directors at Novasenta, a privately-held drug discovery company that focuses on immunotherapy treatment for novel cancer targets, a position she held from April 2021 to March 2024. 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. Su joined our Board of Directors in March 2024. Currently, Dr. Su serves as the Chief Executive Officer of Marengo Therapeutics (“Marengo”) and member of its board of directors, having held both positions since July 2021. Prior to joining Marengo, Dr. Su served as Senior Vice President and Global Head of the Oncology Business Franchise for Merck KGaA (“Merck”) from March 2019 to July 2021 and concurrently as Merck’s US Head of its Oncology Business Unit between July 2020 to July 2021. Dr. Su served as Chief Medical Officer of EMD Serono, part of the larger Merck group, from October 2017 to May 2019. Dr. Su currently serves as a member and the founding chairman of the board of directors at Karyopharm Therapeutics Inc., a publicly-traded pharmaceutical company, a position he has held since August 2023. Before his career in the life sciences industry, Dr. Su served on the faculty of Cynvenio Biosystems, Inc.Duke University Medical School between 2001 to 2006, where he led early oncology clinical studies focusing on mRNA-based and TrueVision Systems Inc. since March 2006. Mr. Gluckcell-based immunotherapy, and then, between 2006 to 2009, served as a consultant to McKinsey & Company, Inc., an international management consulting firm (“McKinsey”), from July 1998 to July 2003. Prior to that, he was Vice Chairman and Director of Bechtel Group, Inc., an engineering, construction and project management company, from 1995 to July 1998. Mr. Gluck is a former managing partner of McKinsey, where he served from 1967 to 1995. Between 1988 and 1994, he was the Managing Director of McKinsey. He also serves as a director of the Foundation Board ofCell and Gene Therapy program at the University of California, Santa Barbara, the Kavli Institute of Theoretical Physics and The New York Presbyterian Hospital (Emeritus). Mr. Gluck was the presiding director of the Hospital Corporation of America. Mr. GluckFlorida. Dr. Su received his B.S.Doctor of Medicine from Manhattan CollegeTechnical University of Dresden in Germany and M.S.his MBA from New Yorkthe University of Toronto in electrical engineering.

Canada. We believe Dr. Su is qualified to serve on our Board based on his substantial drug development and corporate strategy experience in the biotechnology industry complemented by his academic background in life sciences.

Mr. Matthew P. Young has served as a member of our board of directorsBoard since September 2015. Mr. Young currently serves as a managing director at Longitude Capital, a position he has been Executive Vice Presidentheld since August 2022. Before that, Mr. Young was serving as chief operating officer and Chief Financial Officerchief financial officer of GRAIL from October 2019 to December 2021. Prior to joining GRAIL, Mr. Young had served as executive vice president and chief financial officer of Jazz Pharmaceuticals plc(“Jazz”), a role he held since February 2015 and2015. He previously had served as its Senior Vice Presidentsenior vice president and Chief Financial Officerchief financial officer of Jazz since March 2014 and as its Senior Vice President, Corporate Developmentsenior vice president, corporate development of Jazz since April 2013. Prior to joining Jazz, Pharmaceuticals, Mr. Young worked in investment banking for approximately 20 years. From February 2009 to April 2013, Mr. Younghe served as a managing director in global healthcare of Barclays Capital Inc., an investment banking firm, where his role included acting as the co-head of life sciences at Barclays Capital. From 2007 to 2008, Mr. Young served as a managing director of Citigroup Global Markets Inc., an investment banking firm, and, from 2003 to 2007, as a managing director of Lehman Brothers Inc., an investment banking firm. From 1992 to 2003, Mr. Young served in various capacities at other investment banking firms. In 2015, he joined the board of directors of PRA Health Sciences Inc., a contract research company, a position he held until July 2021. Mr. Young currently serves on the board of directors of OrsoBio, Inc., a privately-held biopharmaceutical company. Mr. Young received a B.S. in Economicseconomics and a M.B.A. from the Wharton School of the University of Pennsylvania.

Class III Directors Continuing We believe that Mr. Young is qualified to serve on our Board due to his extensive management experience, significant experience in Office until the 2018 Annual Meeting of Stockholders

Hoyoung Huh, M.D.,life sciences industry and financial expertise.

Elaine V. Jones has served as a member of our board of directors since December 2011 and the chairman of our board of directors since February 2012. Dr. Huh has been a member of the board of directors of Geron CorporationBoard since May 20102019. 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. Prior to this, Dr. Jones held the position of general partner at EuclidSR Partners, a venture firm specializing in private investment in private and public equity within the health sciences, healthcare, biopharmaceutical sectors, until 2008.

The board of directorsBoard met eight times and acted by unanimous written consent fourfive times during the fiscal year ended December 31, 2015.2023. The Audit Committee of the Board met six times, the Compensation Committee of the Board met six 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.,Board, other than Dr. Su, who resigned as a member ofjoined the board of directorsBoard in August 2015, and Matthew P. Young, who was elected as a member of the board of directors in September 2015,March 2024, 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 2024 Annual Meeting of Stockholders. All of our directors attended the virtual 2023 Annual Meeting of Stockholders, except Dr. Su who joined the Board in March 2024.

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,

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 directors

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.

To be considered independent for purposes of Rule 10A-3, a member of an audit committee of a listed company may not, other than in his or hertheir capacity as a member of the audit committee, the board of directors or any other board committee, accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries or be an affiliated person of the listed company or any of its subsidiaries.

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, Alan Ashworth, Ph.D., a member of our Nominating and Corporate Governance Committee, and Zhen Su, M.D., M.B.A., appointed to our Board in March 2024, 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 believes to be necessary or appropriate. The committee may also utilize the services of the Company’s regular legal counsel or other advisors to the Company. The compensation committee retainedCompensation Committee has engaged Radford, an independentAon Hewitt Company, since 2015 as a compensation consultant during each of 2014, 2015to evaluate non-employee director compensation and 2016compensation in comparison to provide a perspectiveindustry peers. For additional information on the competitive labor market.

role of the compensation consultant and the Chief Executive Officer please see “Executive Compensation Summary.”

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.

This section discusses the material components of the executive compensation program for our named executive officers who are base salary, cash bonuses and equity-based compensationnamed in the form“Summary Compensation Table” below.

As a “smaller reporting company” as defined in Item 10(f), we are not required to include a Compensation Discussion and Analysis section and have elected to comply with the scaled disclosure requirements applicable to smaller reporting companies. Nonetheless, we have included some additional information regarding our compensation setting process and our compensation program beyond what Item 10(f) requires of option awards. smaller reporting companies.

The Compensation Committee’s objective is to participatehave compensation programs and practices that are competitive with our peers and industry through a mix of cash (base salary and annual, performance-based cash incentive bonuses) and long-term incentives (equity awards).

The Compensation Committee reviewed our NEOs’ base salaries referencing relevant compensation survey data from Aon (including peer company data), as well as taking into account our Chief Executive Officer’s assessment of individual executive performance (except with respect to his own salary). Based on this review, the Compensation Committee increased our NEOs’ base salaries in our 401(k) plan, health and welfare benefit plans and fringe benefit programs generally available to our other employees.

2015 Compensation2023 effective as of Named Executive Officers

Base Salary

Base salaries are intended to provide a level of compensation sufficient to attract and retain an effective management team, when considered in combination with the other components of our executive compensation program. The relative levels of base salary for our named executive officers areJanuary 1, 2023, as set forth below:

Our annual cash incentive program is designed to reflect each executive officer’s scope of responsibility and accountability with us. Early in 2015, Dr. McCarthy received a 3.5% merit increase in base salary. In August 2015, after consideringreward all employees, including our NEOs, for the advice of Radford, the compensation committee increased Dr. McCarthy’s base salary to $400,000, with a further increase to $425,000 effective upon consummationachievement of the IPO. The initial base salaries for Mr. Goeltz, Dr. Humphrey and Dr. Kavanaugh were determined at the time of hire after considering the competitive market and the compensation received by each at the named executive officer’s prior employer. Please see the “Salary” column in the 2015 Summary Compensation Table for the base salary amounts received by each named executive officer in 2015.

Cash Bonuses

Historically, we have provided our executives with short-term incentive compensation through ourCompany’s annual bonus program.corporate goals, as well as individual performance against annual individual goals. We believe that annual bonusesincentives hold executives accountable, reward executives based on actual business results and help create a “pay for performance” culture. Our 2015 annual cashThere are no minimum or guaranteed bonus program provided

payments for employees, including the NEOs.

Under our cash incentive awards for the achievement of research and development and business development goals (weighted 80% and 20%, respectively)program, every employee, including each NEO, has an established at the beginning of the year by the compensation committee. The research and development portion of the 2015 annual cash bonus program included specific strategic goals relatingperformance-based incentive target, which is equal to the further development of clinical candidates and product pipelines, while the business development portion of the 2015 program included goals relating to strategic partner collaborations.

Each executive’s target bonus is expressed as a percentage of the executive’semployee’s base salary. This percentage increases as levels of responsibility increase.

For 2023, Dr. McCarthy, Dr. Belvin and Mr. Landau had a target bonus opportunity of 60%, 40% and 40% of annual base salary, and is intended to be commensurate with the executive’s position and responsibilities. As a percentage of base salary, the 2015respectively. Each NEO’s target bonus for Dr. McCarthy, Mr. Goeltz, Dr. Humphrey and Dr. Kavanaugh was 40%, 30%, 35% and 30%, respectively, with the bonuses for Mr. Goeltz and Dr. Humphrey pro-rated to reflect their 2015 employment commencement with the Company. Based on our performance, the compensation committee certified a bonus attainment level of 150% of the underlying performance goals. Please see the “Non-Equity Incentive Compensation” column in the 2015 Summary Compensation Table for the amount of annual bonuses paid to each named executive officer in 2015.

In 2015, our board of directors and compensation committee approved a discretionary bonus to Dr. McCarthy of $308,943, with such value relating to a promissory note outstanding at the time from Dr. McCarthy to the company. Dr. McCarthy issued the promissory note to the company as consideration for the exercise of previously granted options to purchase company shares. Dr. McCarthy has paid all amounts owed under the note, and the note has been cancelled. In addition, in connection with the commencement of her employment, Dr. Humphrey received a sign-on bonus of $150,000 as an inducement to commence employment with us.

Equity Awards

We have historically used equity awards in the form of stock options to provide an incentive for our executives to focus on achieving specific performance goals and driving growth in our stock price and long-term value creation and to help us to attract and retain key talent. In February 2015, our board of directors approved option grants to Dr. McCarthy for the purchase of up to 327,744 shares of our common stock and, in August 2015, our board of directors approved option grants as part of our annual equity compensation program to Dr. McCarthy, Mr. Goeltz and Dr. Kavanaugh for the purchase of up to 438,302 shares, 95,878 shares and 85,605 shares, respectively. Also, in May 2015, Dr. Kavanaugh received a milestone-vesting option grant for the purchase of up to 96,736 shares. In connection with the commencement of employment with us, Mr. Goeltz, Dr. Humphrey and Dr. Kavanaugh received option grants for the purchase of 247,675 shares, 378,819 shares (consisting of a new hire time-based grant with respect to 293,214 shares and a new hire grant with respect to 85,605 shares) and 246,042 shares, respectively. Also, during 2015, Dr. Humphrey received an option grant to purchase up to 49,208 shares while serving as a non-employee director. These options generally vest over four years; however, Dr. Humphrey’s director grant vests over three years and Dr. McCarthy and Dr. Humphrey each received an option grant during 2015 that vestsopportunity could be earned based on the achievement of certain strategic milestones. Thesecorporate and individual performance goals, as approved by our Board or Compensation Committee. Our Board and Compensation Committee retain the discretion to modify performance goals or to increase or reduce amounts payable upon achievement of performance goals. In early 2024, our Compensation Committee determined that corporate goals had been achieved at 95% of target and awarded bonuses to Dr. McCarthy, Dr. Belvin and Mr. Landau at 95%, 91% and 96%, respectively, of the NEO’s target bonus opportunity.

In 2023 equity awards to executives (as well as non-executive employees) were comprised of stock option grants, were determinedrestricted stock units, or RSUs, and performance stock units, or PSUs, under our 2015 Equity Incentive Plan and our 2019 Employment Inducement Plan, which we implemented to enhance our ability to make strategically important employment decisions.

Additional annual option grants made after consideringan employee, including an executive officer, has provided services to the competitive labor marketCompany generally vest monthly from the date of grant over four years, subject to the individual’s continued service to us through the applicable vesting date. Additional annual RSU grants to employees will generally vest 33.3% on an annual basis over the next three years of their employment, subject to the individual’s continued service to us through the applicable vesting date. The vesting schedule for the PSUs awarded to executives, including those awarded in 2023, provide that 50% of these PSUs granted will vest within one year of the grant date upon achievement of certain specific Company objectives and the remaining 50% will vest within two years of the grant date upon achievement of additional Company objectives, subject to continued service through the applicable vesting date.

In accordance with our equity grant practices, the exercise price for these stock option grants was equal to the closing price of our common stock as well asreported by the compensation levels deemed necessary to induce Mr. GoeltzNasdaq Global Select Market on the date of grant and Dr. Humphrey to join the company. Please see the Outstanding Equity Awards at December 31, 2015 table for further information regarding the vesting schedule is as described above for new-hire and subsequent grants.

Our NEOs are entitled to certain severance and change in control benefits under the terms applicable to eachof their severance and change of control agreements, as may have been amended and restated, and our equity plans.

Dr. McCarthy’s severance and change of control agreement provides for: (i) 18 months of salary, pro-rated annual target bonus and 18 months of COBRA premiums in the event of a termination without cause or for good reason outside of the 2015 option grants.60 days prior to or 12 months following a change in control and (ii) 24 months of salary, 24 months of annual target bonus, 24 months of COBRA premiums and full acceleration of outstanding equity awards in the event of a termination without cause or for good reason within 60 days prior to or 12 months following a change in control.

The following table provides a summary of compensation paid to our named executive officers for the yearyears ended December 31, 20152023 and with respect to Dr. McCarthy, December 31, 2014.

Summary Compensation Table—Year Ended December��31, 2015

Name and principal position		Fiscal year				Base salary ($)				Bonus ($)(1)				Stock awards ($)				Option awards ($)(2)				Non-equity incentive plan compensation ($)(3)				All other compensation ($)(4)				Total ($)
Sean A. McCarthy, D. Phil. President and Chief Executive Officer			2015 2014				386,321 357,075				308,943 —				—   —				5,558,714 —				306,000 85,698				1,763 953				6,561,741 443,726
Robert C. Goeltz II Chief Financial Officer and Secretary(5)			2015				197,503				—				—				2,154,376				114,095				315				2,466,289
Rachel W. Humphrey, M.D., Chief Medical Officer(5)			2015				127,885				150,000				—				4,484,838				67,423				11,545				4,841,691
W. Michael Kavanaugh, M.D., Chief Scientific Officer and Head of Research and Non- Clinical Development			2015				348,253				—								1,864,560				197,507				2,532				2,412,852

2022.