By Order of the Board of Directors,

Robert Hadfield

Chief Legal Officer and Secretary Boston, Massachusetts                 , 2021

Your vote is conditioned,very important. Whether or not you attend the annual meeting virtually, it is important that your shares be represented. You may vote your proxy through the Internet, by telephone or, if you receive a paper proxy card by mail, by completing and returning the proxy card mailed to you. Voting instructions are provided in the Notice of Internet Availability of Proxy Materials, or, if you receive a paper proxy card by mail, the instructions are printed on your proxy card and included in the proxy statement. If you participate virtually in the annual meeting, you may vote at that time, even if you previously submitted your vote. Even if you plan to participate in the annual meeting, we urge you to vote as soon as possible over the internet, by telephone or by mail as described in the proxy statement.

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Ziopharm Oncology, Inc.

One First Avenue, Parris Building 34, Navy Yard Plaza, Third Floor

Boston, Massachusetts 02129

PROXY STATEMENT

FOR THE ANNUAL MEETING OF STOCKHOLDERS

To Be Held On May 19, 2021

QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

Who is soliciting my vote?

We are providing you with these proxy materials because the board of directors (the “board”) of Ziopharm Oncology, Inc. (sometimes referred to as “we,” “us,” “our” or the “Company”) is soliciting your proxy to vote at the 2021 annual meeting of stockholders (the “annual meeting”), including at any adjournments or postponements thereof. The annual meeting will be held on May 19, 2021 at 9:00 a.m., Eastern Time virtually and exclusively online via live audio-only webcast at www.virtualshareholdermeeting.com/ZIOP2021.

Why did I receive a notice regarding the availability of proxy materials through the internet?

Pursuant to rules adopted by the Securities and Exchange Commission, or the SEC, we have elected to provide access to our proxy materials over the internet. Accordingly, we have sent you a Notice of Internet Availability of Proxy Materials (the “Notice”) because the board is soliciting your proxy to vote at the annual meeting, including at any adjournments or postponements thereof. All stockholders will have the ability to access the proxy materials through the website referred to in the Notice or to request a printed set of the proxy materials. Instructions on how to access the proxy materials over the internet or to request a printed set may be found in the Notice.

We intend to mail the Notice on or about                 , 2021 to all stockholders of record entitled to vote at the annual meeting.

Why are you holding a virtual annual meeting?

As part upon the adoption of Proposal 2 (Removal Proposal). The number of WaterMill Nominees that can be elected pursuantour effort to the Election Proposal will depend on the number ofmaintain a safe and healthy environment for our directors, members of management and stockholders who wish to attend the Board that are removed pursuant to the Removal Proposal. If noneannual meeting, in light of the members of (or appointees to)ongoing coronavirus disease, COVID-19, pandemic we believe that hosting a virtual meeting is in the Board are removed pursuant to the Removal Proposal, and there are no vacancies to fill, none of the WaterMill Nominees can be elected pursuant to the Election Proposal. In the event the Removal Proposal and the Vacancy Proposal pass but the Election Proposal fails to pass, Messrs. Braunstein, Buchi, Ezickson and Tarriff would be removed as directorsbest interest of the Company and pursuantits stockholders and enables increased stockholder attendance and participation because stockholders can participate from any location around the world. Stockholders will have the same rights and opportunities to participate as they would have at an in-person meeting.

Will I receive any other proxy materials by mail?

We may send you a proxy card, along with a second Notice, on or after                 , 2021.

How do I attend the annual meeting?

You cannot attend the annual meeting physically. You can attend the annual meeting by visiting www.virtualshareholdermeeting.com/ZIOP2021, where you will be able to listen to the Vacancy Proposal,annual meeting live, submit questions and vote online.

The annual meeting will start at 9:00 a.m. Eastern Time on May 19, 2021. We encourage you to access the resulting vacanciesannual meeting prior to the start time to allow time for online check-in. We have worked to offer the same

participation opportunities as would be filledprovided at an in-person meeting while further enhancing the online experience available to all stockholders regardless of their location. 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. If you experience technical difficulties during the annual meeting, you should call the technical support phone number provided when you log in to the annual meeting.

In order to enter the annual meeting virtually, you will need the unique 16-digit control number, which is included in the Notice or on your proxy card if you are a stockholder of record of the shares, or included with your voting instruction card and voting instructions received from your broker, bank, trustee, or nominee if you are the beneficial owner of the shares held in “street name.”

What if I cannot virtually attend the annual meeting?

You may vote your shares electronically before the meeting by internet, by proxy or by telephone as described below. You do not need to access the annual meeting audio-only webcast to vote if you submitted your vote via proxy, by internet or by telephone in advance of the annual meeting.

Who can vote at the annual meeting?

Only stockholders of record at the close of business on March 22, 2021 will be entitled to vote at the annual meeting. On the record date, there were 215,205,173 shares of common stock outstanding and entitled to vote. A list of such holders will be open to the examination of any stockholder for any purpose germane to the annual meeting at Ziopharm Oncology, One First Avenue, Parris Building 34, Navy Yard Plaza, Boston, Massachusetts for a period of ten (10) days prior to the annual meeting. Please contact the Secretary of the Company to make arrangements to inspect the list.

Stockholder of Record — Shares Registered in Your Name: If on March 22, 2021, your shares were registered directly in your name with our transfer agent, American Stock Transfer & Trust Company, LLC, then you are a stockholder of record. As a stockholder of record, you may vote at the annual meeting virtually or vote by proxy prior to the annual meeting. Whether or not you plan to attend the annual meeting, we urge you to vote by proxy through the internet, by telephone or using a proxy card that you may request as instructed below, to ensure your vote is counted.

Beneficial Owner — Shares Registered in the Name of a Broker or Bank: If on March 22, 2021, your shares were not registered in your name, but instead are held in an account at a brokerage firm, bank, dealer or similar organization, then you are the beneficial owner of shares held in “street name” and the Notice is being forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting at the annual meeting. As a beneficial owner, you have the right to direct your broker, bank or other agent regarding how to vote the shares in your account. You are also invited to attend the annual meeting. Since you are not the stockholder of record, however, you may not vote your shares at the annual meeting even if you participate virtually unless you request and obtain a valid proxy from your broker, bank or other agent.

What am I voting on?

There are four matters scheduled for a vote:

What if another matter is properly brought before the annual meeting?

The board of directors knows of no other matters that will be presented for consideration at the annual meeting. If any other matters are properly brought before the annual meeting, it is the intention of the persons named in the accompanying proxy to vote on those matters in accordance with their best judgment.

How do I vote?

With respect to Proposal 1, you may vote “For” all the nominees to the board of directors, or you may “Withhold” your vote for any of the nominees you specify. With respect to the other proposals, you may vote “For” or “Against,” or you may abstain from voting.

The procedures for voting are fairly simple:

Stockholder of Record — Shares Registered in Your Name: If you are a stockholder of record, you may vote electronically over the internet before or during annual meeting, vote by proxy over the telephone, vote by proxy through the internet, or vote by proxy using a proxy card that you may request or that we may elect to deliver at a later time. Whether or not you plan to attend the virtual annual meeting, we urge you to vote by proxy to ensure your vote is counted. You may still attend the annual meeting virtually and vote electronically at the annual meeting even if you have already voted by proxy. You may vote as follows:

Beneficial Owner — Shares Registered in the Name of a Broker or Bank: 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 containing voting instructions from that organization rather than from us. Simply follow the voting instructions in the Notice to ensure that your vote is counted. To vote electronically at the annual meeting, you must obtain a valid proxy from your broker, bank, or other agent. Follow the instructions from your broker or bank included with these proxy materials, or contact your broker or bank 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.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you own as of March 22, 2021.

If I am a stockholder of record and I do not vote, or if I return a proxy card or otherwise vote without giving specific voting instructions, what happens?

If you are a stockholder of record and do not vote by completing your proxy card, by telephone, through the internet or by voting electronically at the annual meeting, your shares will not be voted.

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, as applicable, “For” the election of all seven nominees for director, “For” the ratification of the selection by the Company’s stockholders.audit committee of the board of directors of RSM US LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2021, “For” the approval, on an advisory basis, of the compensation of our named executive officers as disclosed in this proxy statement, and “For” an amendment to our charter to effect the increase of the authorized number of shares of our common stock from 250,000,000 shares to 350,000,000 shares. If any other matter is properly presented at the annual meeting, your proxyholder (one of the individuals named on your proxy card) will vote your shares using his or her best judgment.

If I am a beneficial owner of shares held in street name and I do not provide my broker or bank with voting instructions, what happens?

If you are a beneficial owner of shares held in street name and you do not instruct your broker, bank or other agent how to vote your shares, your broker, bank or other agent may still be able to vote your shares in its discretion. Under the rules of the New York Stock Exchange, or NYSE, brokers, banks and other securities intermediaries that are subject to NYSE rules may use their discretion to vote your “uninstructed” shares with respect to matters considered to be “routine” under NYSE rules, but not with respect to “non-routine” matters. Proposals 1 and 3 are considered to be “non-routine” under NYSE rules meaning that your broker may not vote your shares on those proposals in the absence of your voting instructions. However, Proposals 2 and 4 are considered to be “routine” matters under NYSE rules meaning that if you do not return voting instructions to your broker by its deadline, your shares may be voted by your broker in its discretion on Proposals 2 and 4. Accordingly, if you own shares through a nominee, such as a broker, bank or other agent, please be sure to instruct your nominee how to vote to ensure that your vote is counted on all of the proposals.

If you are a beneficial owner of shares held in street name, in order to ensure your shares are voted in the way you would prefer, you must provide voting instructions to your broker, bank or other agent by the deadline provided in the materials you receive from your broker, bank or other agent.

How are proxies solicited for the Annual Meeting?

At this time we have not engaged a proxy solicitation firm, but we may decide to retain the services of a proxy solicitation firm in the future if we believe it is appropriate under the circumstances. If we do engage a proxy solicitor, we will pay for the entire cost of soliciting proxies. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners.

What does it mean if I receive more than one Notice?

If you receive more than one Notice, your shares may be registered in more than one name or in different accounts. Please follow the voting instructions on each Notice to ensure that all of your shares are voted.

Can I change my vote after submitting my proxy?

Stockholder of Record: Shares Registered in Your Name

Yes. You can revoke your proxy at any time before the final vote at the annual meeting. If you are the record holder of your shares, you may revoke your proxy in any one of the following ways:

Your most current proxy card, telephone proxy or internet proxy is the one that is counted.

Beneficial Owner: Shares Registered in the event thatName of Broker or Bank

If your shares are held by your broker or bank as a nominee or agent, you should follow the Removal Proposal and Board Size Proposal pass but the Vacancy Proposal and Election Proposal fail to pass, oneinstructions provided by your broker or more vacancies may arise on the Board that wouldbank.

How are votes counted?

Votes will be filledcounted by the affirmativeinspector of election appointed for the annual meeting, who will separately count, for the proposal to elect directors (Proposal 1), votes “For,” “Withhold” and broker non-votes; and with respect to all other proposals, votes “For” and “Against,” abstentions and, if applicable, broker non-votes. Abstentions will have the same effect as “Against” votes on Proposals 2, 3 and 4, and will have no effect on Proposal 1. Broker non-votes on Proposals 1 and 3 will have no effect and will not be counted towards the vote total for any of those proposals.

What are “broker non-votes”?

As discussed above, when a beneficial owner of shares held in street name does not give voting instructions to his or her broker, bank or other securities intermediary holding his or her shares as to how to vote on matters

deemed to be “non-routine” under NYSE, the broker, bank or other such agent cannot vote the shares. These un-voted shares are counted as “broker non-votes.” Proposals 1 and 3 are considered to be “non-routine” under NYSE rules and therefore, we expect broker non-votes to exist in connection with those proposals. Broker non-votes will have no effect on those proposals.

As a reminder, if you are a beneficial owner of shares held in street name, in order to ensure your shares are voted in the way you would prefer, you must provide voting instructions to your broker, bank or other agent by the deadline provided in the materials you receive from your broker, bank or other agent.

How many votes are needed to approve each proposal?

The following table summarizes the minimum vote needed to approve each proposal and the effect of abstentions and broker non-votes.

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least a majority of the outstanding shares entitled to vote are deemed present at the annual meeting in person or represented by proxy. On the record date, there were 215,205,173 shares outstanding and entitled to vote. Thus, the holders of 107,602,587 shares must be deemed present in person or represented by proxy at the annual meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or if you vote electronically at the annual meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the holders of a majority of shares deemed present at the remaining membersannual meeting in person or represented by proxy may adjourn the annual meeting to another date.

How can I find out the results of the Board, although lessvoting at the annual meeting?

Preliminary voting results will be announced at the annual meeting. In addition, final voting results will be published in a current report on Form 8-K that we expect to file within four business days after the annual meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.

PROPOSALS

Proposal 1

Election of Directors

Our board of directors presently has eight directors: Christopher Bowden M.D.; Kevin Buchi; Heidi Hagen; James Huang; Robert W. Postma; Mary Thistle; Jaime Vieser; and Holger Weis. Each of Dr. Bowden and Ms. Hagen was previously elected by the stockholders. In March 2021, Mr. Buchi notified our board of directors of his intention to retire as a member our board, effective as of this annual meeting, and, as a result, our board has elected to reduce the size of our board from eight to seven directors at that time.

On March 22, 2021, our board of directors nominated all of our existing directors, other than Mr. Buchi, for election at the annual meeting. If elected, each of our proposed nominees has consented to serve as one of our directors, to hold office until our next annual meeting of stockholders and until his or her successor has been duly elected and qualified, or, if sooner, until his or her earlier death, resignation or removal. Proxies cannot be voted for a quorum,greater number of persons than the number of nominees named in the proxy statement. If any director nominee should withdraw or otherwise become unavailable to serve, the proxies which would have otherwise been voted for that director nominee may be voted for a substitute director nominee selected by our board. We are not aware of any reason that a sole remainingnominee will be unable or unwilling to serve as a director.

The following table sets forth each nominee to be elected at the annual meeting, the year each nominee was first elected as a director, the position(s) currently held by each nominee with us and the year each nominee’s term will expire, if such nominee is elected at the annual meeting.

In 2016, we adopted a director resignation policy. Under this policy, any nominee in an uncontested election who does not receive a majority of the votes cast (i.e. receives a greater number of votes “withheld” from his or her election than votes “for” in such election) shall submit his or her offer of resignation for consideration by the corporate governance and nominating committee. The corporate governance and nominating committee shall consider all of the relevant facts and circumstances and recommend to the board the action to be taken with respect to such offer of resignation, and the board will then act on such recommendation.

Our corporate governance and nominating committee seeks to assemble a board that, as a whole, possesses the appropriate balance of professional and industry knowledge, financial expertise and management experience

necessary to oversee and direct our business. The corporate governance and nominating committee maintains a goal of recruiting members who complement and strengthen the skills of other members and who also exhibit integrity, collegiality, sound business judgment and other qualities that the corporate governance and nominating committee views as critical to effective functioning of the board.

None of the director nominees is related by blood, marriage or adoption to any of our other director nominees or executive officers. Further, none of the director nominees is party to an arrangement or understanding with any person pursuant to which the nominee is to be selected or nominated for election as a director, except that certain arrangement described in the section entitled “Certain Relationships and Related Transactions—Certain Related-Party Transactions—WaterMill Settlement Agreement” in this proxy statement.

Vote Required

Directors are elected by a plurality of the votes castof the holders of shares deemed present in person or represented by proxy and entitled to vote on the election of directors. Accordingly, if a quorum is present, the seven nominees receiving the highest number of “For” votes will be elected. Shares represented by executed proxies will be voted, if authority to do so is not withheld, for the election of the seven nominees named above.

The board recommends that you vote “FOR” the election of each named nominee.

Proposal 2

Ratification of Selection of Independent Registered Public Accounting Firm

The audit committee of the board has selected RSM US LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2021. RSM US LLP has audited our financial statements since 2010. A representative of RSM US LLP is expected to virtually attend the annual meeting. He or she will have an opportunity to make a statement if he or she so desires and will be available to respond to appropriate questions from stockholders.

We are not required by statute or our bylaws or other governing documents to obtain stockholder ratification of the appointment of RSM US LLP as our independent registered public accounting firm. The audit committee has submitted the selection of RSM US LLP to the stockholders for ratification as a matter of good corporate practice. If the stockholders do not ratify the appointment, the audit committee may reconsider its selection. Notwithstanding the proposed ratification of the selection of RSM US LLP by the Company’sstockholders, the audit committee, in its discretion, may direct the appointment of a new independent registered public accounting firm at any time during the year without notice to, or the consent of, the stockholders, if the audit committee determines that such a change would be in our best interests and the best interests of our stockholders.

Vote Required

REASONS TO REJECT THE WATERMILL PROPOSALSThe affirmative vote of the holders of a majority of the shares deemed present in person or represented by proxy and entitled to vote at the annual meeting will be required to ratify the selection of RSM US LLP. Abstentions will be counted toward the vote total for Proposal 2 and will have the same effect as “Against” votes.

Principal Accountant Fees and Services

The following table presents the aggregate fees billed by RSM US LLP for the years ended December 31, 2020 and 2019.

Other than as discussed above, we did not incur any fees of RSM US LLP for audit-related, tax or other services in 2020 or 2019.

All fees described above were pre-approved by the audit committee.

Pre-Approval Policy and Procedures

The WaterMill Proposalsaudit committee has adopted a policy and procedures for the pre-approval of audit and non-audit services rendered by our independent registered public accounting firm, RSM US LLP. The policy generally pre-approves specified services in the defined categories of audit services, audit-related services and tax services up to specified amounts. Pre-approval may also be given as part of the audit committee’s approval of the scope of the engagement of the independent registered public accounting firm or on an individual, explicit, case-by-case basis before the independent registered public accounting firm is engaged to provide each service. The pre-approval of services may be delegated to one or more of the audit committee’s members, but the decision must be reported to the full audit committee at its next scheduled meeting.

The board recommends that you vote “FOR” the ratification of the selection of RSM US LLP

as our independent registered public accounting firm for our fiscal year ending December 31, 2021.

Proposal 3

Advisory Vote on Executive Compensation

Under the Dodd-Frank Wall Street Reform and Consumer Protection Act, or the Dodd-Frank Act, and Section 14A of the Securities Exchange Act of 1934, as amended, or the Exchange Act, our stockholders are entitled to vote to approve, on an advisory basis, the compensation of our named executive officers as disclosed in this proxy statement in accordance with the SEC rules. At the 2017 annual meeting of stockholders, our stockholders indicated their preference that we solicit a non-binding advisory vote on the compensation of the named executive officers, commonly referred to as a “say-on-pay vote,” every year. The board has adopted a policy that is consistent with that preference indicated by our stockholders. Accordingly, this year we are again asking the stockholders to approve, on an advisory basis, the compensation of our named executive officers as disclosed in this proxy statement.

This vote is not intended to address any specific item of compensation, but rather the overall compensation of our named executive officers and the philosophy, policies and practices described in this proxy statement. The compensation of our named executive officers is disclosed in the section entitled “Executive Compensation” below, including the tabular and narrative disclosures set forth in such section under the headings “Executive Compensation Tables” and “Compensation Discussion and Analysis.” As discussed in those disclosures, we believe that our compensation policies and decisions are focused on pay-for-performance principles and strongly aligned with our stockholders’ interests. Compensation of our named executive officers is designed to enable us to attract and retain talented and experienced executives, whose knowledge, skills and performance are critical to our success, and motivate these executive officers to achieve our business objectives and to lead us in a competitive environment.

We are asking our stockholders to indicate their support for the WaterMill Nomineescompensation of our named executive officers as described in this proxy statement by casting a non-binding advisory vote “FOR” the following resolution:

“RESOLVED, that the stockholders hereby approve the compensation of the “named executive officers” of Ziopharm Oncology, Inc., as disclosed in the section entitled “Executive Compensation” in the proxy statement for the Ziopharm Oncology, Inc. 2021 Annual Meeting of Stockholders pursuant to take over nearly half the Board,compensation disclosure rules of the Securities and thereby exercise significant influence overExchange Commission, including the Compensation Discussion and Analysis, compensation tables and narrative discussion.”

Vote Required

The affirmative vote of the holders of a majority of the shares deemed present in person or represented by proxy and entitled to vote at the annual meeting will be required to approve, on an advisory basis, the compensation of our named executive officers as described herein. Because the vote is advisory, it will not be binding on us, the board or our compensation committee. Nevertheless, the views expressed by our stockholders, whether through this vote or otherwise, are important to us and, accordingly, the board and our compensation committee intend to consider the results of this vote in making determinations in the future of your Company. We askregarding executive compensation arrangements.

The board recommends that you carefully consider whethervote “FOR” the proposal to support WaterMillapprove the compensation of our

named executive officers, as described in lightthis proxy statement.

Proposal 4

Approval of Certificate of Amendment of the potential risksAmended and costsRestated Certificate of Incorporation to Increase the Company discussed below.Total Number of Authorized Shares of Common Stock

Overview

Proposal 1 (By-Law Restoration Proposal): We recommend rejectionOur board of Proposal 1 because this proposaldirectors has determined that it is speculativeadvisable and is designed to nullify unspecified amendments to the By-Laws that may be adopted by the Board acting in its best judgment for reasons unrelated to the WaterMill Consent Solicitation. The automatic repeal of all duly adopted By-Law amendments, irrespective of their content, would have the unfortunate effect of repealing properly adopted By-Law amendments determined by the Board to be in the best interests of the Company and its stockholders, even if unrelated to the WaterMill Consent Solicitation.

Proposal 2 (Removal Proposal): We recommend rejection of Proposal 2 because we believe that removal of half of the Board is not in the best interests of the Company and its stockholders. The Board does not believe that removing directors just a few months after the 2020 Annual Meeting is in the best interests of the Company and its stockholders. We encourage you to review the background and qualifications of each director that WaterMill is attempting to remove from the Board, which is available under “Information about the Current Directors of the Company” on page 11 of this Consent Revocation Statement.

Proposal 3 (Vacancy Proposal): We recommend rejection of Proposal 3 because we do not believe that removing the Board’s ability to fill seats resulting from an increase in the number of directors or vacancies is in the best interests of the Company and its stockholders. In our view, the Board must retain the ability to change its composition to ensure that it has the proper skills and experience.

Proposal 4 (Board Size Proposal): We recommend rejection of Proposal 4 because we do not believe that preventing the Board from changing the size of the Board or capping the size of the Board is clearly in the best interests of our stockholders. Instockholders to amend our view,amended and restated certificate of incorporation (our “charter”), to increase the Board must retain the ability to adjust its membership to ensure that it has the proper composition to maximize stockholder value.

Proposal 5 (Election Proposal): We recommend rejectiontotal number of Proposal 5 because we do not believe that another director election just a few months after the 2020 Annual Meeting is in the best interests of the Company and its stockholders. The Company has added four new directors to the Board since June 2019. If all four incumbent directors were removed and all WaterMill Nominees were elected, this would result in four of seven directors having served on the Board for less than a year.

FOR THE FOREGOING REASONS, THE BOARD STRONGLY BELIEVES THAT THE WATERMILL CONSENT SOLICITATION IS NOT IN THE BEST INTERESTS OF THE COMPANY AND ITS STOCKHOLDERS. WE URGE STOCKHOLDERS TO REJECT THE WATERMILL CONSENT SOLICITATION AND REVOKE ANY CONSENT PREVIOUSLY SUBMITTED.

DO NOT DELAY. IN ORDER TO HELP ENSURE THAT THE CURRENT BOARD IS ABLE TO ACT IN YOUR BEST INTERESTS, PLEASE SIGN, DATE AND MAIL THE ENCLOSED GREEN CONSENT REVOCATION CARD TODAY.

BACKGROUND OF THE SOLICITATION

The Company held its 2020 Annual Meeting on June 29, 2020. At the 2020 Annual Meeting, three directors (Scott Braunstein, Elan Z. Ezickson and Douglas W. Pagán) did not receive “FOR” votes from a majority of the votes cast. Accordingly, in accordance with the Board’s director resignation policy adopted in 2016, each of these three directors tendered their resignations for consideration by the Board’s Corporate Governance and Nominating Committee.

Following the 2020 Annual Meeting, starting in the month of July 2020, Scott Tarriff, the Chairman of the Board, Laurence Cooper, the Chief Executive Officer (CEO) of the Company, and Heidi Hagen, a director of the Board, engaged in numerous conversations with stockholders of the Company, including with Robert Postma. During these calls, Mr. Postma conveyed his beliefs that the Board needed to be refreshed and that certain directors should resign from the Board. During one of the calls, Mr. Postma suggested his relative as a potential Board candidate. In response, Mr. Tarriff, Dr. Cooper and Ms. Hagen indicated that the Board was conducting a process following best practices for Board refreshment, including by engaging an independent nationally recognized director search firm to conduct a thorough search for candidates whose appointment would be in the best interests of the Company and all of its stockholders. During the July 2020 conversations, Mr. Postma claimed that he was in close contact with representatives of MSD Partners, L.P. (“MSD”) and other stockholders with respect to matters relating to the composition of the Board.

On July 27, 2020, James Huang was appointed to the Board with a term that will expire at the Company’s 2021 annual meeting of stockholders (the “2021 Annual Meeting”). Prior to Mr. Huang’s appointment to the Board, multiple stockholders, including MSD and WaterMill, had recommended to members of the Board that Mr. Huang be appointed to the Board.

During the first week of August 2020, Mr. Postma had a telephone conversation with Mr. Huang during which Mr. Postma welcomed Mr. Huang to the Board.

On September 22, 2020, the Company announced the Board’s appointment of J. Kevin Buchi to the Board and as Chair of the Board’s Audit Committee, with a term that will expire at the 2021 Annual Meeting. In addition, the Company announced that the Board had accepted the resignation of Mr. Pagán. The Company also indicated that the Board would continue to review its composition to ensure that the skills and experience of the Company’s directors support the progress and future prospects of Ziopharm’s business.

On October 15, 2020, Mr. Postma delivered a letter to the Company notifying the Company of WaterMill’s intent to solicit written consents from the Company’s stockholders for the WaterMill Proposals and requesting that the Company set a record date for the WaterMill Consent Solicitation.

On October 16, 2020, WaterMill filed its preliminary consent solicitation statement with the SEC.

On October 16, 2020, the Company issued a press release acknowledging the filing of WaterMill’s preliminary consent solicitation statement and recommending that stockholders refrain from taking any action at that time.

Also on October 16, 2020, Robert Hadfield, the General Counsel of the Company, held a telephone conference with Mr. Postma.

On October 21, 2020, the Company filed its preliminary consent revocation statement with the SEC.

On October 26, 2020, WaterMill filed a revised preliminary consent solicitation statement with the SEC.

On October 27, 2020, the Company filed this revised preliminary Consent Revocation Statement with the SEC.

INFORMATION ABOUT THE CONSENT SOLICITATION

Voting Securities and Record Date

The Record Date for the WaterMill Consent Solicitation is the close of business on October 20, 2020. As of the Record Date, there were [●]authorized shares of Common Stock outstanding and entitled to vote. Each share of Common Stock will be entitled to one vote in connection with the WaterMill Consent Solicitation.

Only stockholders of record as of the Record Date are eligible to execute, withhold and revoke consents in connection with the WaterMill Proposals. Record holders of Common Stock who wish to revoke a previously executed consent should sign, date and promptly mail the GREEN Consent Revocation Card.

Persons beneficially owning shares of Common Stock (but not holders of record), such as persons whose ownership of Common Stock is held through a broker, bank or other financial institution, should contact such broker, bank or financial institution and instruct such person to execute the green Consent Revocation Card on their behalf. Your broker, bank or financial institution may also permit you to revoke your consent by completing, signing, dating and delivering the enclosed GREEN Consent Revocation Card in the postage-paid envelope provided. By checking “REVOKE MY CONSENT” and signing, dating and delivering the GREEN Consent Revocation Card, you will be instructing your broker, bank, financial institution or other nominee holder to act on your behalf to take any steps necessary to ensure that a revocation is properly executed on your behalf. Any abstention on an executed green Consent Revocation Card will have the same effect as voting against the WaterMill Proposals and revoking any prior consent to the WaterMill Proposals.

Effectiveness of Consents

Under Delaware law and the By-Laws, our stockholders may act without a meeting, without prior notice and without a vote, if consents in writing setting forth the action to be taken are signed by the holders of outstandingcommon stock having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were present and voted. Under Section 228 of the DGCL, the WaterMill Proposals will become effective if valid, unrevoked consents signed by the holders of a majority of the shares of Common Stock outstanding and entitled to vote as of the Record Date are delivered to the Company within 60 days of the earliest dated consent delivered to the Company. A stockholder delivered the first written consent to the Company on October 20, 2020. Therefore, properly completed and unrevoked consents must be received from holders of the requisite number of shares of Common Stock no later than December 19, 2020 under Delaware law in order for the WaterMill Proposals to become effective.

BECAUSE THE WATERMILL PROPOSALS COULD BECOME EFFECTIVE BEFORE THE EXPIRATION OF THE 60-DAY PERIOD DISCUSSED ABOVE, WE URGE YOU TO ACT PROMPTLY AND RETURN THE GREEN CONSENT REVOCATION CARD TODAY.

Effect of a GREEN Consent Revocation Card

A stockholder may revoke any previously signed consent by marking “REVOKE MY CONSENT” or “ABSTAIN” on the GREEN Consent Revocation Card and signing, dating and promptly mailing the GREEN Consent Revocation Card using the postage-paid envelope provided. A consent may also be revoked by delivery of a written revocation of your consent to WaterMill. Stockholders are urged, however, to deliver all consent revocations in the postage-paid envelope provided.

If you sign and date the GREEN Consent Revocation Card but make no direction with respect to any WaterMill Proposal or all WaterMill Proposals, your shares will be voted in accordance with the recommendations of the Board as follows: REVOKE MY CONSENT for each of WaterMill Proposals 1, 2, 3, 4 and 5, except that with respect to Proposal 2, you will not be deemed to have revoked your consent to the removal of any director whose name is written in the space provided on the GREEN Consent Revocation Card and with respect to Proposal 5, you will not be deemed to have revoked your consent to the election of any director whose name is written in the space provided on the GREEN Consent Revocation Card.

The revocation of any previously executed consent or GREEN Consent Revocation Card should be signed and have a date subsequent to the previously executed consent or GREEN Consent Revocation Card. The revocation is not required to state the number of shares held unless you wish to revoke your consent with respect to less than all shares as to which you previously executed a consent, in which case you must state the number of250,000,000 shares to which your revocation relates. In addition, if you have more than one account with respect to which you have executed a consent, the revocation should identify the relevant account for which the consent is being revoked. Marking “DO NOT REVOKE MY CONSENT” for a WaterMill Proposal will have no effect on any earlier dated consent that you may have delivered to WaterMill with respect to such WaterMill Proposal or, if you have not previously delivered a consent to WaterMill consenting to such WaterMill Proposal, will have no effect on the outcome of the WaterMill Consent Solicitation.

If you beneficially own shares of Common Stock outstanding and entitled to vote (but are not a record holder), including because your shares of Common Stock that you owned on the Record Date were held for you in an account with a stock brokerage firm, bank nominee or other similar “street name” holder, you are not entitled to revoke your consents with respect to such shares directly, but rather must give instructions to the stock brokerage firm, bank nominee or other “street name” holder to grant or revoke consent for the shares of Common Stock outstanding and entitled to vote held in your name. Accordingly, you should contact the person responsible for your account and direct him or her to execute the enclosed GREEN Consent Revocation Card on your behalf. If your bank, brokerage firm, dealer, trust company or other nominee provides for consent instructions to be delivered to them by telephone or internet, instructions will be included with the GREEN Consent Revocation Card. You will also be authorizing Ziopharm to act on your behalf to take any steps necessary to ensure that such revocation is properly executed. Alternatively, you can contact the person responsible for your account and direct him or her to revoke a consent by executing the enclosed green Consent Revocation Card on your behalf. If you choose to do so, we encourage you to confirm in writing your instructions to the person responsible for your account and provide a copy of those instructions to the Company at the address set forth above so that the Company will be aware of your instructions and can attempt to ensure each instruction is followed.

YOU HAVE THE RIGHT TO REVOKE ANY CONSENT YOU MAY HAVE PREVIOUSLY GIVEN TO WATERMILL. TO DO SO, YOU ONLY NEED TO SIGN, DATE AND PROMPTLY MAIL THE GREEN CONSENT REVOCATION CARD THAT ACCOMPANIES THIS CONSENT REVOCATION STATEMENT. WHEN MARKING BOXES ON THE GREEN CONSENT REVOCATION CARD “REVOKE MY CONSENT” AND “ABSTAIN” WILL HAVE THE EFFECT OF REVOKING A PRIOR CONSENT.

Any consent revocation may itself be revoked by marking, signing, dating and delivering a written revocation of your Consent Revocation Card to the Company or to WaterMill or by delivering to WaterMill a subsequently dated white consent card that WaterMill sent to you.

Results of the Consent Solicitation

The Company anticipates retaining an independent inspector of elections in connection with the WaterMill Consent Solicitation. The Company intends to notify stockholders of the results of the WaterMill Consent Solicitation by issuing a press release, which it will also file with the SEC as an exhibit to a Current Report on Form 8-K promptly following the receipt of a report of the inspector of elections.

Participants in the Solicitation

Under applicable regulations of the SEC, each of Ziopharm’s directors and certain of Ziopharm’s officers and employees are “participants” in this consent revocation solicitation. For certain required information about Ziopharm’s directors, officers and employees who are participants in the solicitation, please see “Appendix A — Additional Information Regarding Participants in the Solicitation” to this Consent Revocation Statement. Other than the persons described herein as participants, no general class of employee of the Company will be employed to solicit stockholders in connection with the solicitation. However, in the course of their regular duties, employees may be asked to perform clerical or ministerial tasks in furtherance of the Company’s consent revocation solicitation.

Cost and Method of this Consent Revocation Solicitation

The cost of this consent revocation solicitation will be borne by the Company. The Company estimates that the total expenditures relating to the Company’s consent revocation solicitation (other than salaries and wages of350,000,000 shares. On March 22, 2021, our officers and regular employees), will be approximately $[●], of which $[●] has been incurred as of the date of this Consent Revocation Statement. Our directors and certain of our officers and employees may solicit consent revocations in person or by email or other electronic means or by telephone. We will pay these directors, officers and employees no additional compensation for these services. We will reimburse banks, brokers and other nominees for their reasonable, out-of-pocket expenses incurred in forwarding this Consent Revocation Statement and related materials to, and obtaining instructions relating to such materials from, beneficial owners of Common Stock.

The Company has retained Morrow as its soliciting agent. Morrow has advised the Company that approximately [●] of its employees will be involved in the solicitation of consent revocations by Morrow on behalf of the Company. Morrow will solicit consent revocations by mail, telephone, facsimile and email. Under our agreement with Morrow, Morrow will receive an estimated fee of $[●] plus reimbursement of its reasonable, out-of-pocket expenses for its services. In addition, Morrow and certain related persons will be indemnified against certain liabilities arising out of or in connection with the engagement.

INFORMATION ABOUT THE CURRENT DIRECTORS OF THE COMPANY

The following sets forth information about the current members of the Board as of the date of this Consent Revocation Statement, including the experience, qualifications, attributes or skills that led to the conclusion that each such person should serve as a director. In connection with the 2020 Annual Meeting, which was the most recent annual meeting of stockholders of the Company at which directors were up for election, each of directors Scott Tarriff, Christopher Bowden, Scott Braunstein, Laurence Cooper, Elan Z. Ezickson and Heidi Hagen consented to be named in the proxy statement for such meeting and to serve if elected. Directors J. Kevin Buchi and James Huang were appointed to the Board following the 2020 Annual Meeting and will be up for election at the 2021 Annual Meeting; all of the current directors of the Company have consented to be named as directors in this Consent Revocation Statement and to continue to serve their term as directors.

Mr. Tarriff is the chair of our Board. He has served as a member of our Board since September 2015 and served as the Board’s non-executive Lead Director from August 2018 until April 2019 when he was appointed our chair. Mr. Tarriff has served as the Chief Executive Officer and as a member of the board of directors adopted resolutions approving the proposed certificate of Eagle Pharmaceuticals, Inc. since its inceptionamendment of our charter (the “certificate of amendment”) in January 2007. Prior to joining Eagle, Mr. Tarriff held various executive positions at Par Pharmaceutical Companies, Inc., a publicly-traded developer, manufacturer and marketer of specialty pharmaceuticals, includingsubstantially the form attached hereto as President and Chief Executive Officer from September 2003 to September 2006, after joining Par in 1998. Prior toAppendix A. At that Mr. Tarriff held various positions with Bristol-Meyers Squibb, a publicly-traded biopharmaceutical company, including senior director of marketing. Mr. Tarriff has served as a member of thetime, our board of directors declared the proposed certificate of Synthetic Biologics, Inc., a publicly-traded biotechnology company, since February 2012amendment to be advisable and previously served on the board of directors of Clinical Data, Inc., a publicly-traded pharmaceutical company, from September 2009 until its acquisition by Forest Laboratories, Inc. in April 2011. Mr. Tarriff holds a B.S. in marketing from Pennsylvania State University and an M.B.A. from Rider College. 

Laurence James Neil Cooper, M.D., Ph.D. Chief Executive Officer and Director
Age: 56
Director Since: 2018

Dr. Cooper has served as our Chief Executive Officer since May 2015 and as a director since October 2018. Prior to joining us, Dr. Cooper led the Pediatric Cell Therapy service (formally named the bone marrow transplantation (“BMT”) program) as a tenured professor at the University of Texas M.D. Anderson Cancer Center (“MD Anderson”), where he had worked since 2006. In addition to caring for children, adolescents and young adults undergoing autologous and allogeneic BMT at MD Anderson, he led a laboratory translating immunology into clinical practice. This program had multiple investigator-initiated trials that infused T cells and NK cells to target malignancies. Dr. Cooper also holds an appointment as a Visiting Scientist at MD Anderson. Dr. Cooper obtained his B.A. at Kenyon College in Gambier, Ohio and M.D. and Ph.D. degrees at Case Western Reserve University in Cleveland before training in Pediatric Oncology and BMT at the Fred Hutchinson Cancer Research Center in Seattle.

Christopher Bowden, M.D.
Age: 59
Director Since: 2019

Dr. Bowden, an oncology drug development executive with more than 20 years leadership experience including the approval of several cancer medicines, has served as a member of our Board since October 2019. He has been the chief medical officer of Agios Pharmaceuticals since May 2014. Previously, Dr. Bowden was vice president product development oncology, at Genentech for eight years. From 2003 to 2006, he was the executive director for EMEA regions for Bristol-Myers Squibb. Earlier, Dr. Bowden held positions of increasing responsibility in oncology clinical development, at Pharmacia Corporation and Janssen Pharmaceutical. Dr. Bowden was previously on the oncology faculty at the University of Virginia Health Science Center. Since 2017, Dr. Bowden has served as a member of the board of directors of miRagen Therapeutics, Inc., a publicly-traded biopharmaceutical company discovering and developing proprietary RNA-targeted therapies with a specific focus on microRNAs. Dr. Bowden received his M.D. from Hahnemann University School of Medicine followed by internal medicine training at Roger Williams Medical Center and the Providence VA Medical Center, Rhode Island. He completed his medical oncology fellowship at the National Cancer Institute Medicine Branch. Dr. Bowden is board certified in internal medicine and medical oncology.

Dr. Braunstein has served as a member of our Board since September 2018. Dr. Braunstein has served as the chief executive officer of Marinus Pharmaceuticals, Inc., a publicly-traded pharmaceuticals company, since August 2019, and as a member of its board of directors since September 2018. Dr. Braunstein is also an operating partner at Aisling Capital, a private investment firm, a position he has held since August 2015. From 2015 to 2018, he held positions of increasing responsibility at Pacira Pharmaceuticals, Inc., a publicly traded specialty pharmaceutical company, including most recently serving as its Chief Operating Officer. His prior roles at Pacira including serving as its Senior Vice President of Strategy and Chief Strategy Officer. Prior to then, Dr. Braunstein served as a healthcare portfolio manager at Everpoint Asset Management from 2014 through 2015. From 2002 to 2014, he worked in various positions at JP Morgan Asset Management, a division of JPMorgan Chase & Co., most recently as a managing director, senior portfolio manager for the JPM Global Healthcare Fund and the JPM asset global equity analyst for the U.S. pharmaceutical and biotechnology industry. Dr. Braunstein has served as a member of the board of directors of Trevena, Inc., a traded pharmaceutical company, since September 2018, on the board of directors of Constellation Pharmaceuticals, a publicly traded biopharmaceutical company, since February 2019, and on the board of directors of Artara Therapeutics, Inc., a publicly-traded company, since May 2018. Dr. Braunstein previously served as a member of the board of directors of Esperion Therapeutics, Inc. from 2015 until 2020. Dr. Braunstein is board certified in internal medicine, having completed his residency at the New York Hospital/Cornell Medical Center, and achieved the title of assistant clinical professor of medicine at Albert Einstein College of Medicine and for Columbia University Medical Center. He earned his B.S. from Cornell University and his M.D. from the Albert Einstein College of Medicine at Yeshiva University.

J. Kevin Buchi
Age: 65
Director Since: 2020

Mr. Buchi has served as a member of our Board since September 2020. Mr. Buchi served as Chief Executive Officer and a director of Biospecifics Technologies Corp. from October 2019 until April 2020. Mr. Buchi served as Impax Laboratories, LLC’s Interim President and Chief Executive Officer from December 2016 until March 2017 and as a member of the Impax board of directors from November 2016 until the completion of the combination of Impax and Amneal Pharmaceuticals. Mr. Buchi served as President and Chief Executive Officer of TetraLogic Pharmaceuticals from August 2013 to December 2016. Before TetraLogic, he served as Corporate Vice President of Global Branded Products at Teva Pharmaceutical Industries Limited from 2011 to May 2012. Mr. Buchi was Chief Executive Officer of Cephalon, Inc., which was acquired by Teva Pharmaceutical Industries Limited in October 2011. Mr. Buchi has served as a member of the board of directors of Dicerna Pharmaeuticals, Inc. since August 2018 and was appointed Chairman of its board of directors in January 2019. In addition, Mr. Buchi currently serves as a director of Amneal Pharmaceuticals Inc. and Benitec Biopharma Ltd. Mr. Buchi previously served on the board of directors of EPIRUS Biopharmaceuticals, Inc. from June 2013 to July 2016, Alexza Pharmaceuticals, Inc. from January 2013 to June 2016, Forward Pharma A/S from December 2012 to May 2016, and Stemline Therapeutics, Inc. from March 2012 to May 2016. Mr. Buchi received his B.A. degree in Chemistry from Cornell University and a Masters of Management degree from the J.L. Kellogg Graduate School of Management, Northwestern University.

Elan Z. Ezickson
Age: 57
Director Since: 2018

Mr. Ezickson has served as a member of our Board since September 2018. Mr. Ezickson served as Chief Operating Officer & Head of Corporate Development for Scholar Rock Holding Corporation from August 2014 until his retirement in December 2018. Prior to Scholar Rock, Mr. Ezickson served as Executive Vice President and Chief Operating Officer of Aveo Pharmaceuticals, Inc., where he worked from 2003 to July 2013. Previously, Mr. Ezickson worked at Biogen Inc. in roles of increasing responsibility, including serving as the President of Biogen Canada, Program Executive and Associate General Counsel. Since December 2019, Mr. Ezickson has served on the board of directors of Marinus Pharmaceuticals, Inc., a publicly-held company focused on developing and commercializing innovative therapeutics to treat patients suffering from rare seizure disorders. Mr. Ezickson holds a B.A. in Political Science from Yale University and a J.D. from the Columbia University School of Law.

Heidi Hagen
Age: 52
Director Since: 2019

Ms. Hagen has served as a member of our Board since June 2019. Ms. Hagen has held the position of a biotechnology and pharmaceutical operations and technology consultant with HH Consulting LLC since October 2012. Since October 2015, Ms. Hagen has served as Co-founder and Advisor for Vineti, Inc., a privately-held company that develops and sells cloud-based software platforms for ordering, manufacturing and delivering personalized medicines. Previously, Ms. Hagen served as interim Chief Commercial Officer at ZappRx, Inc. from January 2015 to June 2015. Prior to that, Ms. Hagen served as Global Chief Operating Officer at Sotio LLC, a biotechnology company developing new therapies for the treatment of cancer and autoimmune diseases using its immunotherapy platform and proprietary cell-based technologies, from March 2013 to April 2014. Prior to joining Sotio, Ms. Hagen was Senior Vice President of Operations at Dendreon Corporation from 2002 to 2012, where she was responsible for, among other duties, manufacturing and supply chain operations. Prior to joining Dendreon, Ms. Hagen spent nearly ten years at Immunex Corporation, where she held several positions in drug development and supply chain and operations management. Ms. Hagen has served on the board of directors of Vericel Inc., a publicly-held company developing advanced cell therapies and specialty biologics for the sports medicine and severe burn care markets, since August 2013, and on the board of directors of Lykan Biosciences LLC, a privately held contract manufacturing company, since June 2019. Ms. Hagen earned her B.S. in cell and molecular biology, M.S. in bioengineering, and MBA at the University of Washington.

James Huang
Age: 55
Director Since: 2020

Mr. Huang has served as a member of our Board since July 2020. Mr. Huang joined Kleiner Perkins Caufield & Byers China, or KPCB China, as a managing partner in 2011 and focuses on the firm’s life sciences practice. Prior to joining KPCB China, Mr. Huang was a managing partner at Vivo Ventures, a venture capital firm specializing in life sciences investments. Before joining Vivo in 2007, Mr. Huang was president of Anesiva, a biopharmaceutical company focused on pain-management treatments. He also held senior roles in business development, sales, marketing and R&D with Tularik Inc. (acquired by Amgen), GlaxoSmithKline LLC, Bristol-Myers Squibb and ALZA Corp. (acquired by Johnson & Johnson). Mr. Huang is also founding and managing partner of Panacea Venture, a global venture fund focusing on investments in innovative and transformative early and growth stage healthcare and life science companies. Mr. Huang is Chairman of the Board at Kindstar Global (Beijing) Technology, Inc., Windtree Therapeutics, Inc., JHL Biotech, Inc., Tactiva Therapeutics, LLC, and Chime Biologics Limited and Director at CASI Pharmaceuticals Inc. and XW Laboratories Inc. Mr. Huang received an M.B.A. from the Stanford Graduate School of Business and a B.S. degree in chemical engineering from the University of California, Berkeley.

INFORMATION REGARDING OUR BOARD OF DIRECTORS AND CORPORATE GOVERNANCE

This section provides further information regarding the Board and the independence of our directors and describes key corporate governance guidelines and practices that we have adopted.

Independence of the Board of Directors

Our Board has undertaken a review of the independence of our directors and considered whether any director has a relationship that, in the opinion of the Board, would interfere with the exercise of independent judgment in carrying out the responsibilities of a member of our Board. Based upon information requested from and provided by each director concerning such director’s background, employment and affiliations, including family relationships, the Board has determined that all of our directors, other than Dr. Cooper, are “independent directors,” as such term is defined in Nasdaq Rule 5605(a)(2). In making these determinations, our Board considered the current and prior relationships that each non-employee director has with our Company and all other facts and circumstances that our Board deemed relevant in determining their independence, including the beneficial ownership of our capital stock by each non-employee director.

Board Leadership Structure

The Board has appointed an independent director, Scott Tarriff, to serve as its non-executive Board chair. The Board has elected to separate the chair function from that of the Chief Executive Officer, who serves as our principal executive officer, due to a belief that separating these functions, and empowering an independent director to chair the Board meetings, reinforces the independence of the Board in its oversight of our business and affairs. In addition, we believe that having an independent chair creates an environment that is more conducive to objective evaluation and oversight of management’s performance, increasing management accountability and improving the ability of the Board to monitor whether management’s actions are in the best interests of the Company and our stockholders and is accordingly submitting the proposed certificate of amendment for approval by our stockholders. As a result,

If our stockholders approve this Proposal 4, we believe that having an independent chair can enhanceexpect to file the effectivenesscertificate of amendment with the Secretary of State of the BoardState of Delaware to increase the number of authorized shares of our common stock as a whole.soon as practicable following stockholder approval. In this regard, upon filing of the certificate of amendment with the Secretary of State of the State of Delaware, the first paragraph of section four of our charter would be amended as follows, with the proposed additions double-underlined and proposed deletions stricken through:

“4. Number of Shares. The total number of shares of all classes of stock that the Corporation shall have authority to issue isTwo Hundred Eighty Million (280,000,000)Three Hundred Eighty Million (380,000,000) shares consisting of:Two Hundred Fifty Million (250,000,000)Three Hundred Fifty Million (350,000,000) shares of common stock, $.001 par value per share (“Common Stock”); and Thirty Million (30,000,000) shares of preferred stock, $.001 par value per share (“Preferred Stock”).”

Of the 250,000,000 shares of our common stock currently authorized, as of the close of business on March 12, 2021, there were 215,180,173 shares of common stock outstanding. In addition to the 215,180,173 shares of common stock outstanding on March 12, 2021, as of March 12, 2021:

The proposed certificate of amendment would increase the number of shares of common stock that the Company is authorized to issue from 250,000,000 shares of common stock to 350,000,000 shares of common stock, representing an increase of 100,000,000 shares of authorized common stock, with a corresponding increase in the total authorized capital stock, which includes common stock and Stockholder Meetingspreferred stock, from 280,000,000 shares to 380,000,000 shares.

Reasons for the Increase in Authorized Shares

At present, the board of directors has no arrangements or understandings to issue the additional shares of common stock. However, the board of directors desires to have the shares available to provide additional flexibility to use Company common stock for business and financial purposes in the future as well to have sufficient shares available to provide appropriate equity incentives for our employees. The additional shares may be used for various purposes, which include establishing strategic relationships with other companies; expanding our business through the acquisition of other businesses, therapeutics or product candidates; raising capital; providing equity incentives to employees, officers, directors, consultants and/or advisors; stock splits and stock dividends; and other purposes. For example, we will need to raise substantial additional capital to, among other things, fund our operations, conduct and/or complete clinical trials, continue our research and development activities, seek regulatory approval for our product candidates and commercialize our product candidates, if any such product candidates receive regulatory approval for commercial sale, and the additional shares may be used for a financing if we have an appropriate opportunity. If this Proposal 4 is not approved by our stockholders, it is possible that our business development and financing alternatives for us may be limited by the lack of sufficient unissued and unreserved authorized shares of common stock, and stockholder value may be harmed, perhaps severely, by this limitation. In addition, our success depends in part on our continued ability to attract, retain and motivate highly qualified management and clinical and scientific personnel, and if this Proposal 4 is not approved by our stockholders, the lack of sufficient unissued and unreserved authorized shares of common stock to provide future equity incentive opportunities that our compensation committee deems appropriate could adversely impact our ability to achieve these goals. In summary, if our stockholders do not approve this Proposal 4, we may not be able to access the capital markets, complete corporate collaborations or partnerships, attract, retain and motivate employees, and pursue other business opportunities integral to our growth and success, all of which could severely harm our business and our prospects.

Effects of the Increase in Authorized Shares

The Board met nine times during 2019, either in person oradditional common stock to be authorized by teleconference. Each director attended at least 75%stockholder approval of this Proposal 4 would have rights identical to the currently outstanding shares of our common stock. Approval of this Proposal 4 and issuance of the aggregateadditional authorized shares of common stock would not affect the rights of the holders of currently outstanding shares of our common stock, except for effects incidental to increasing the number of meetingsshares of our common stock outstanding, such as dilution of any earnings per share and voting rights of current holders of common stock. The additional shares of common stock authorized by the approval of this Proposal 4 could be issued by our board of directors without further vote of our stockholders except as may be required in particular cases by our charter, applicable law, regulatory agencies or the rules of the Board andNasdaq. Under our charter, stockholders do not have preemptive rights to subscribe to additional securities that may be issued by us, which means that current stockholders do not have a prior right thereunder to purchase any new issue of common stock in order to maintain their proportionate ownership interests in our Company.

The proposed certificate of amendment to increase the committees onnumber of authorized shares of our common stock could, under certain circumstances, have an anti-takeover effect. The additional shares of common stock that would become available for issuance if this Proposal 4 is approved could also be used by us to oppose a hostile takeover attempt or to delay or prevent changes in control or our management. For example, without further stockholder approval, the board could adopt a “poison pill” which he or she served, held during 2019would, under certain circumstances related to an acquisition of our securities not approved by the board, give certain holders the right to acquire additional shares of common stock at a low price, or the portion thereofboard could strategically sell shares of common stock in a private transaction to purchasers who would oppose a takeover or favor the current board. Although this Proposal 4 to increase the authorized common stock has been prompted by business and financial considerations and not by the threat of any hostile takeover attempt (nor is the board currently aware of any such attempts directed at us), nevertheless, stockholders should be aware that heapproval of this Proposal 4 could facilitate future efforts by us to deter or she wasprevent changes in control, including transactions in which the stockholders might otherwise receive a director or committee member.premium for their shares over then current market prices.

Abandonment

Although we have no formal policy regarding directors’ attendance atcurrently expect that, if this Proposal 4 is approved by our annual meetings,stockholders, we encourage such attendance by memberswill file the certificate of amendment of our charter with the Secretary of State of the Board. AllState of Delaware as soon as practicable following stockholder approval, notwithstanding approval of this Proposal 4 by our stockholders, our board of directors may, in its sole discretion, abandon the proposed certificate of amendment of our charter and determine, prior to the filing of certificate of amendment of our charter with the Secretary of State of the then-currentState of Delaware, not to effect the proposed amendment to our charter to increase the number of authorized shares of our common stock from 250,000,000 shares to 350,000,000 shares. If this Proposal 4 is approved by our stockholders and our board of directors attendeddetermines to exercise such discretion, we will publicly disclose that fact and our 2019board of directors’ reason or reasons for its determination.

Vote Required

The affirmative vote of the holders of a majority of the outstanding shares on the record date. Abstentions will be counted toward the vote total for Proposal 4 and will have the same effect as “Against” votes.

The board recommends that you vote “FOR” the proposal to approve the amendment of our charter.

STOCKHOLDER PROPOSALS FOR THE 2022 ANNUAL MEETING OF STOCKHOLDERS

For a proposal to be considered for inclusion in our proxy materials for presentation at the 2022 annual meeting of stockholders either in person or by teleconference.

Board Committees

The Board has established three standing committees: an audit committee, a compensation committee and a corporate governance and nominating committee. Each committee operates under a charter that has been approved by the Board. Current copies of each committee’s charter are posted on the “Investors—Corporate Governance” section of our website, www.ziopharm.com. Our website and its contents are not incorporated into this Consent Solicitation Revocation Statement. The current members of the committees are as follows:

Audit

Compensation

Nominating

Christopher Bowden, M.D.

Scott Braunstein, M.D.

Laurence Cooper, M.D., Ph.D.

Elan Ezickson

Heidi Hagen

J. Kevin Buchi

Scott Tarriff*

* = Board Chair  = Chair  = Member

Audit Committee

The current members of the audit committee are Mr. J. Kevin Buchi, who serves as the committee’s Chair, Mr. Elan Ezickson and Mr. Scott Tarriff. As set forth in the audit committee charter, the primary responsibility of the audit committee ispursuant to oversee our financial reporting processes and internal control system on behalf of the Board. In that regard, the audit committee is responsible for, among other things, the appointment, compensation, retention and oversight of the work performed by the independent registered public accounting firm employed by us.

Each member of the audit committee is an “independent director,” as such term is defined in Nasdaq Rule 5605(a)(2), and meets the criteria for independence set forth in Rule 10A-3(b)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). The Board has also determined that each of the audit committee members is able to read and understand fundamental financial statements and that at least one member of the audit committee has past employment experience in finance or accounting. The Board has determined that at least one member of the audit committee, Mr. J. Kevin Buchi, is an “audit committee financial expert,” as that term is defined in Item 407(d)(5)(ii) of Regulation S-K promulgated14a-8 under the Exchange Act.

The audit committee held four meetings during 2019.

Compensation Committee

The current members ofAct, the compensation committee are Mr. Scott Tarriff, who serves as the committee’s Chair, Dr. Scott Braunstein and Ms. Heidi Hagen. As set forth in the compensation committee charter, the compensation committee reviews our compensation policies and practices and makes recommendations to the Board in connection with all compensation matters affecting our executive officers.

Each member of the compensation committee is an “independent director,” as such term is defined in Nasdaq Rule 5605(a)(2), and meets the criteria for independence set forth in Rule 10A-3(b)(1) under the Exchange Act.

The compensation committee held six meetings during 2019.

Corporate Governance and Nominating Committee

The current members of the corporate governance and nominating committee are Ms. Heidi Hagen, who serves as the committee’s Chair, Dr. Christopher Bowden and Mr. Elan Ezickson. As set forth in the corporate governance and nominating committee charter, the primary responsibility of the corporate governance and nominating committee is to consider and make recommendations to the Board concerning the appropriate size, function and needs of the Board and its committees. In that regard, the corporate governance and nominating committee is, among other things, responsible for establishing criteria for membership on the Board, recruiting and recommending candidates to fill newly created or vacant positions on the Board and reviewing any candidates recommended by stockholders. In addition, the corporate governance and nominating committee evaluates and assesses the performance of the Board as a whole and its committees.

Each member of the corporate governance and nominating committee is an “independent director,” as such term is defined in Nasdaq Rule 5605(a)(2), and meets the criteria for independence set forth in Rule 10A-3(b)(1) under the Exchange Act.

The corporate governance and nominating committee held three meetings during 2019.

Director Nomination Process

The corporate governance and nominating committee (or a subcommittee thereof) recruits and considers director candidates and presents qualified candidates to the full Board for consideration. There is no fixed process for identifying and evaluating potential candidates to be nominees for directors, and there is no fixed set of qualifications thatproposal must be satisfied before a candidate will be considered. Rather, the corporate governance and nominating committee has the flexibility to consider such factors as it deems appropriate. These factors may include education, general business and industry experience, ability to act on behalf of stockholders, potential concerns regarding independence or conflicts of interest and other factors relevant in evaluating Board nominees.

The corporate governance and nominating committee believes that a Board comprised of directors with diverse skills and experiences relevant to our industry and operations will result in efficient and competent oversight of our various core competencies, which include drug development, strategic partnering, commercialization activities, regulatory compliance, corporate finance and accounting. As such, the corporate governance and nominating committee gives consideration to the interplay of a director candidate’s experience with that of other members of the Board and the evolving needs of our business.

In April 2019, our Board updated our corporate governance policies to reflect the importance our Board places on diversity. More specifically, we have updated our policies to emphasize our commitment to seeking to attain diversity and balance among directors of race, gender, geography, thought, viewpoints, backgrounds, skills, experience, and expertise. As a result, under our policies any search firm retained to assist the corporate governance and nominating committee in seeking candidates for the Board will be instructed to seek to include diverse candidates in terms of race, gender, geography, thought, viewpoints, backgrounds, skills, experience, and expertise from, among other areas, the traditional corporate environment, government, academia, private enterprise, non-profit organizations, and professions such as accounting, finance, marketing, human resources, and legal services.

Qualified candidates will be considered without regard to race, color, religion, sex, ancestry, national origin or disability, and the corporate governance and nominating committee will consider director candidates recommendedreceived by security holders. If the corporate governance and nominating committee approves a candidate for further review following an initial screening, the corporate governance and nominating committee will establish an interview process for the candidate. Generally, the candidate will meet with at least one member of the corporate governance and nominating committee, along with other members of the Board, and management, including our Chief Executive Officer. Contemporaneously with the interview process, the corporate governance and nominating committee will conduct a comprehensive conflicts-of-interest assessment of the candidate. The corporate governance and nominating committee will consider reports of the interviews and the conflicts-of-interest assessment to determine whether to recommend the candidate to the full Board. The corporate governance and nominating committee will also take into consideration the candidate’s personal attributes, including, without limitation, personal integrity, loyalty to us and concern for our success and welfare, willingness to apply sound and independent business judgment, awareness of a director’s vital part in our good corporate citizenship and image, time available for meetings and consultation on our matters and willingness to assume broad, fiduciary responsibility.

Recommendations for candidates to be considered for election to the Board at our annual stockholders’ meeting may be submitted to the corporate governance and nominating committee by our stockholders. In order to make such a recommendation, a stockholder must submit the recommendation in writing to the Chairperson of the corporate governance and nominating committee, in care of our Secretary at our principal executive offices at One First Avenue, Parris Building 34, Navy Yard Plaza, Third Floor, Boston, Massachusetts 02129, by no later than            , 2022 unless the date of 2022 annual meeting of stockholders is changed by more than 30 days from the one-year anniversary of this year’s annual meeting, in which case the deadline will be a reasonable time before we begin to distribute the proxy materials for the 2022 annual meeting of stockholders. Due to the complexity of the respective rights of the stockholders and us in this area, any stockholder desiring to propose such an action is advised to consult with his or her legal counsel with respect to such rights. We suggest that any such proposal be submitted to us by certified mail, return receipt requested.

Rule 14a-4 under the Exchange Act governs our use of our discretionary proxy voting authority with respect to a stockholder proposal that the stockholder has not sought to include in our proxy statement. Rule 14a-4 provides that if a proponent of a proposal fails to notify us at least 12045 days prior to the month and day of mailing of the prior year’s proxy statement, management proxyholders will be allowed to use their discretionary voting authority as to whether the proposal is raised at the annual meeting, without any discussion of the matter. If a stockholder wishes to bring a matter before the stockholders at the 2022 annual meeting of stockholders but does not notify us before             , 2022 (or a reasonable time before we begin to distribute the proxy materials for the 2022 annual meeting of stockholders if the date of the previous2022 annual meeting of stockholders is changed by more than 30 days from the one-year anniversary of this year’s annual meeting), for all proxies we receive, the management proxyholders will have discretionary authority to vote on the matter, including discretionary authority to vote in opposition to the stockholder’s proposal.

CURRENT DIRECTORS, DIRECTOR NOMINEES AND EXECUTIVE OFFICERS

Our Board of Directors

Set forth below are the names and certain information about each of our directors as of March 12, 2021. The information presented includes each director’s age, principal occupation and business experience for the past five years and the names of other public companies of which he or she has served as a director during the past five years. In addition, the table contains information about the specific and particular experience, qualifications, attributes or skills of each current director and each nominee for director at the annual meeting proxy statement. To enablethat led the corporate governance and nominating committee to evaluatebelieve that such current director was appropriate for nomination at a previous annual meeting of stockholders and, in the candidate’s qualifications, stockholder recommendations must includecase of each nominee for director at the annual meeting, that such nominee should serve on the board following information:election at the annual meeting.

(1) Mr. Buchi will be retiring from the board of directors and its committees at the end of his term, which expires at the annual meeting.

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There are no family relationships among any of our directors, director nominees or executive officers. None of our executive officers is related by blood, marriage or adoption to any of our directors, director nominees or executive officers.

Laurence James Neil Cooper, M.D., Ph.D. Dr. Cooper’s biography can be found under “Information About the Current Directors of the Company” above.

EXECUTIVE COMPENSATION

Satyavrat Shukla has served as our Chief Financial Officer since July 2019. Prior to joining us, Mr. Shukla served in leadership roles at Vertex Pharmaceuticals from July 2012 until July 2019, most recently as Vice President and Head of Corporate Finance, where he led Vertex’s long-range planning, annual budgeting and investor relations analytics processes. Prior to Vertex, Mr. Shukla was a Principal at Cornerstone Research, an economic and financial analysis firm, where he led large, multi-disciplinary teams providing consulting services spanning financial modeling, assessment of product lines and businesses, and evaluation of operating and financial strategy and performance for life science clients. Prior to Cornerstone, he worked for finance consulting firms LECG and Putnam and Hayes & Bartlett. Mr. Shukla earned a BA in Economics from Harvard University and an MBA in Finance and Strategy from Yale University. He also holds the Chartered Financial Analyst designation.

Robert Hadfield has served as our Executive Vice President, General Counsel, Secretary and Chief Compliance Officer since December 2018 and as our General Counsel and Secretary since April 2018. Previously, Mr. Hadfield was the General Counsel of Longwood Fund, a health care venture capital fund, from November 2017 until April 2018. Prior to Longwood Fund, Mr. Hadfield was the General Counsel of Flex Pharma, Inc. from April 2014 until November 2017. Mr. Hadfield was an attorney in the business department of Cooley LLP from August 2007 to August 2011 and then from April 2012 to April 2014. From August 2011 to April 2012, Mr. Hadfield served as the Corporate Counsel at Kiva Systems, Inc. prior to its acquisition by Amazon.com, Inc. Mr. Hadfield began his career as a financial analyst in the health care investment banking group of Cowen Inc. Mr. Hadfield holds a B.S. degree in Finance from Providence College and a J.D. from the Georgetown University Law Center.

Jill Buck has served as our Executive Vice President, General Manager Gene Therapy since January 2019 and served as our Senior Vice President of Clinical Operations from January 2017 to January 2019, and as our Vice President of Clinical Operations from September 2015 to January 2017. Previously, Ms. Buck served as Group Vice President of Global Clinical Operations at Synageva Biopharm Corp from January 2014 to September of 2015, and Vice President of Global Clinical Operations from June 2013 to January 2014 where she oversaw the teams responsible for the clinical trials resulting in US, EU and Japanese approvals of sebelipase alfa for LAL Deficiency. Prior to Synageva, Ms. Buck held roles of increasing responsibility in Clinical Operations at the Company, Averion International, Control Delivery Systems and The TIMI Study Group at Brigham and Women’s Hospital. Ms. Buck holds a BA degree in English and Communications from Boston College.

Eleanor de Groot, Ph.D. has served as our Executive Vice President, General Manager Cell Therapy since January 2019 and oversees our CAR-T and TCR-T cell therapy platform, including the collaboration with MD Anderson. She initially joined us in July 2015 as our Senior Vice President, Program Management and Business Development. Prior to joining us, Dr. de Groot was Vice President of Technical Operations and Project Planning and Management at Helsinn Therapeutics US, Inc. While at Helsinn and its predecessor companies, Sapphire Therapeutics and Rejuvenon Corporation, Dr. de Groot held multiple roles of increasing responsibility, leading technical operations, in particular chemistry, manufacturing, and controls (CMC) development for its drug candidates from preclinical through Phase III, from April 2002 to July 2015. Prior to Helsinn, Dr. de Groot was a staff engineer at Guilford Pharmaceuticals (now Eisai) and a process engineer at Shell Chemical Company. She earned Ph.D. and M.S. degrees in chemical engineering from Stanford University in 1995 and 1991, respectively, and a B.S. in chemical engineering from Massachusetts Institute of Technology (MIT) in 1990. Dr. de Groot received an M.B.A. degree from Rice University in 2014.

Kevin G. Lafond has served as our Sr. Vice President Finance, Chief Accounting Officer and Treasurer since June 2013 and is our principal accounting officer. Previously, Mr. Lafond served as our Corporate Controller since he joined us in February 2009 until June 2013. Prior to joining us, Mr. Lafond served as Controller of Helicos Biosciences Corporation, a public life sciences equipment manufacturer, from February 2007 to October 2008. Mr. Lafond holds a bachelor’s degree from Plymouth State University, master’s degrees in both accounting and taxation from Bentley University and is a Certified Public Accountant.

executive compensation

Compensation Discussion and Analysis

Overview

This Compensation Discussion and Analysis explains our executive compensation philosophy and objectives, programs and practices compensation setting process and the material elements of 20192020 compensation offor our named executive officers.

There is also discussion of the 2021 compensation decisions for our new Interim Chief Executive Officer and Interim Chief Financial Officer. As discussed in Proposal 3 of this proxy statement, we are conducting our annual advisory vote on executive compensation, or “say-on-pay” vote, that requests approval of the compensation provided to our named executive officers, as described in this subsection titled “—Compensation Discussion and Analysis” and in the tables and accompanying narrative contained below under this section “Executive Compensation.” Please review our compensation philosophies, the design of our executive compensation programs in the context of this say-on-pay vote.

For 2019,2020, our named executive officers were:

Executive Summary

Business Highlights

During 2020 and the first quarter of 2021, we evolved our focus to our cell therapy programs and, in particular, our TCR-T program. During this period, we made significant progress advancing this program and our CAR-T and Controlled IL-12 programs, which included the following achievements:

In 2019, we laid

CAR+ T Program

Compensation Highlights

Key features of our executive compensation program include the following:

Table below:

		*  Average excludes Satyavrat Shukla, who was hired in 2019.

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Stockholder Engagement

In response to shareholder feedback, the board and Actions in Response to 2018 Advisory Vote on Executive Compensationcompensation committee recently implemented the following governance changes:

Beginning in early 2020, we began engaging with several investors to understand their perspectives regarding our business and organization. At our 20192020 annual meeting of stockholders in June 2020, three of our directors, Scott Braunstein, Elan Ezickson and Douglas Pagan, received less than 50% of the total votes cast, and an amendment to our certificate of incorporation to increase our authorized number of shares was not approved. At the 2020 annual meeting, our stockholders approved, on an advisory basis, the compensation of our named executive officers as disclosed in our 2019 proxy statement. Thebut the proposal was supported by only approximately 91.7%56.7% of the total votes cast, a 42.3% increase over our 2018 “say on pay” vote. We believecast.

The board of directors felt it was important to understand the reasons for the results at the 2020 annual meeting and, therefore, we engaged with several stockholders to discuss this increase of support was, in part, the result of the stockholder outreach that we commenced and changes we made to our executive compensation program over the past two years. Following the 2018 “say on pay” advisory vote, membersoutcome. On July 20, 2020, following feedback from several of our largest stockholders, James Huang was appointed as a director by the board of directors. In addition, the board of directors and management began preparations to expand our discussions with stockholders to understand the perspectives of a broader group.

In October 2020, Watermill Asset Management Corp., Robert W. Postma, Jaime Vieser and in some cases membersHolger Weis (collectively, “Watermill”) initiated a consent solicitation to, among other things, remove Scott Braunstein, Kevin Buchi, Elan Ezickson and Scott Tarriff from the board of our Board, activelydirectors and to replace them with Messrs. Postma, Vieser and Weis. In response to the consent solicitation by Watermill, we engaged in a dialogue with several of our largest stockholders to gain a better understanding ofunderstand their views regardingon the board, compensation matters and company performance. The feedback we received from stockholders in these conversations related primarily to our executive compensation programapproach to investor communications and engagement, capital allocation and company performance.

The board of directors had also begun national searches to identify new directors to replace the directors that had received less than 50% of the votes cast at the 2020 annual meeting, each of whom had tendered his resignation for the board’s consideration under our director resignation policy. As a result of this search, on September 21, 2020, Kevin Buchi was appointed by the board to replace Mr. Pagan, and on November 15, 2020, Mary Thistle was appointed by the board to replace Dr. Braunstein. On December 3, 2020, Mr. Ezickson resigned from the board, effective immediately.

On December 10, 2020, Mr. Shukla, our Chief Financial Officer, delivered notice of his resignation effective December 31, 2020 in order to pursue another opportunity.

On December 15, 2020, Watermill delivered consents for stockholder action by written consent in lieu of a meeting removing Mr. Tarriff and adding Messrs. Vieser and Weis to the board of directors. As described more fully below, on February 4, 2021, we entered into a settlement agreement with Mr. Postma, pursuant to which Mr. Postma was appointed to the board of directors.

On February 24, 2021, Ms. Hagen was appointed our Interim Chief Executive Officer, replacing Dr. Cooper, who also resigned from our board of directors on February 24, 2021. Given the recent IND clearance for our TCR-T clinical trial and our transition to a clinical stage cell therapy company, the board of directors believed we would benefit from Ms. Hagen’s deep experience in cell and gene therapy, and her extensive experience in operations management and commercializing innovative technologies. Given Mr. Huang’s significant background launching, building and raising capital for leading biotechnology companies, the board of directors also elected Mr. Huang as well as other governance matters. Specifically, we contacted approximately 20our Executive Chair on February 24, 2021.

The board of directors and management expect to continue improving upon our engagement with our stockholders to understand their views of our largest stockholders, and in the first and second quarters of 2019, we held informative discussions with several of our top holders who expressed interest in speaking with us.

In response to the feedback and actions resulting from our advisory vote and stockholder outreach, our Boardbusiness, corporate governance practices and compensation committee: 

practices. Our compensation committee generally evaluates our compensation practices at or near the end of each year and will continue to monitor and evaluate our executive compensation program throughout the year in light of our stockholders’ views, before making any appropriate adjustments during the 2020 2021 year-end compensation review process. Our compensation committee expects to continue to consider the outcome of our “say on pay” votes and our stockholders’ views when making future compensation decisions for our named executive officers.

Overview of our Executive Compensation Program

Objectives, Philosophy and Elements of Compensation

We believe that our executive compensation programs should:

We believe that by structuring the executive compensation program so that a significant portion of each of our named executive officers’ pay is at risk, including a meaningful equity-based component, we can best ensure our named executive officers are incentivized to maximize our performance and increase value for our stockholders. To this end, our program is comprised of three primary elements:

Other Significant Factors in Determining Executive Compensation

The biotechnology industry is characterized by a very long product development cycle, including a lengthy research and development period and a rigorous approval phase involving preclinical studies, clinical trials and governmental regulatory approval. As a result, many of the traditional commercial product metrics, such as product sales, revenues and profits are irrelevant for a development-stage biotechnology company like us. Instead, the specific performance factors our compensation committee considers when determining the compensation of our named executive officers include factors related to development progress, commercialization progress, and cash/expense management, which are typical pre-commercial drug development metrics:

These performance factors are considered by our compensation committee in connection with our annual performance reviews described below and are a critical component in the determination of annual cash and equity incentive awards for our executives.

Role of our Compensation Committee, Management and Consultant

Compensation Committee

Our compensation committee is responsible for reviewing, evaluating, approving, administering and interpreting our executive compensation and benefits policies, programs and plans, including our equity compensation plans. In particular, with respect to the compensation of our named executive officers, our

compensation committee is responsible for reviewing and recommending to the outside, independent and non-employee members of the Boardboard of directors the compensation levels and performance goals relevant to the compensation of these officers, and for evaluating the officers’ performance in light of those goals and objectives. The outside, independent and non-employee members of the Boardboard of directors approved the compensation committee’s recommendations for the 20192020 compensation of our named executive officers.

Management

Our human resources, finance and legal departments work with our Chief Executive Officer to design and develop new executive compensation programs, to recommend changes to existing compensation programs, to recommend financial and other performance targets to be achieved under those programs, to prepare analyses of financial data, to prepare peer group data comparisons and other briefing materials for consideration by the compensation committee and ultimately, to implement the decisions of the compensation committee.

The Chief Executive Officer recommends to the compensation committee for its discussion and ultimately, approval, proposed corporate performance and strategic goals and their relative weighting for the upcoming fiscal year, and provides input on the level of attainment of the prior year’s strategic goals, for purposes of determining awards under the annual performance bonus plan for all our executives, including the Chief Executive Officer. For executives other than the Chief Executive Officer, the compensation committee will consider the individual performance of the executives, as assessed by the Chief Executive Officer, and the compensation recommendations submitted to the compensation committee by the Chief Executive Officer. Our Chief Executive Officer and other members of management generally attend our compensation committee meetings for a portion of the meeting. No executive officer was present or voted in the compensation committee or the Board’sboard of directors’ final determinations regarding the amount of any component of his or her own 20192020 compensation package.

Consultant

Consultant

TheDuring 2019 and early 2020, the compensation committee engaged Haigh and Company, or Haigh, as an independent compensation consultant. Haigh was engaged by and reportsreported directly to the compensation committee and was determined to have no conflicts of interests in a review conducted by the compensation committee.

As part of its duties, Haigh provided the compensation committee with the following services:

Beginning in March 2020, our compensation committee engaged FW Cook as its independent compensation consultant. FW Cook provided independent market findings to the compensation committee conducted a performancein August 2020 and independence assessment of Haigh with respect to Haigh’s role in recommending or determining the amount and form of executive compensation during the fiscal year ended December 31, 2019. Other than providing limitedhas provided advice to our management and our compensation committee regarding competitive salary data, Haigh did not provide any other services to us in 2019. The compensation committee also considered that the individual representative of Haigh who works directly with the compensation committee has no other business relationships with the Board, management or the Company, Haigh’s own policies on ethics, stock ownershipas to Interim Chief Executive Officer compensation andnon-employee director compensation in 2021. FW Cook was determined to be free of conflicts of interest and the total revenue that Haigh received from us in 2019 and how this amount comparedable to Haigh’s 2019 total gross revenues. As a result, theoperate as an independent compensation committee concluded that Haigh’s services to the compensation committee during 2019 did not raise any conflict of interest.advisor.

Peer Group, Survey Sources and Market Data

Peer Group

In November 2018, in consultation with Haigh, the compensation committee evaluated the list of companies that should be included in the peer group used as a reference point in determining 2019 compensation, which we refer to as the 2018 peer group. The selected 2018 peer group companies were chosen based upon the following selection criteria:

The compensation committee determined that the foregoing selection criteria were relevant for selecting the 2018 peer group because at such time we had approximately 46 employees, a market value of approximately $384.0 million and an R&D trailing expense of approximately $40.0 million. The following 19 companies were approved by the compensation committee as the 2018 peer group for purposes of determining the January 2019 equity grants and in setting 2019 base salary and bonus target levels:

In November 2019, in consultation with Haigh, the compensation committee evaluated the list of companies that should be included in the peer group used as a reference point in making 2020 executive compensation decisions, which we refer to as the 2019 peer group. The selected 2019 peer group companies were chosen based upon the following selection criteria:

The compensation committee determined that the foregoing selection criteria were relevant for selecting the 2019 peer group because at such time we had approximately 65 employees, a market value of approximately $771.9 million and an R&D trailing expense of approximately $35.9 million. The following 19 companies were approved by the compensation committee as the 2019 peer group to be used for purposes of setting 2020 base salary and bonus target levels for our executives:

Other Survey Sources

In making its 2019 executive compensation decisions,2020, the compensation committee reevaluated the 2019 peer group to determine whether it should also reviewed drug development survey databe used as a supplement toreference point in making 2021 executive compensation decisions. Based on its evaluation, the compensation committee decided that the 2019 peer data.group remained appropriate, except that Arqule, Inc. was removed because it had been acquired.

20192020 Compensation Decisions

Overview

As a general approach, the compensation committee reviews each component and the total compensation for each named executive officer to ensure their compensation is in line with the peer group and/or survey market data. The compensation committee does not target a specific percentile and references market data as context.

All of the named executive officers in 2020 had total compensation value, as disclosed in the Summary Compensation Table, that was below the median of the peer group data provided to the compensation committee, except that the compensation of Dr. de Groot, our EVP GM Cell Therapy, was slightly above the median based on her importance to the Company and to ensure internally equitable relationships with the other officers. Further, all named executive officers had lower total compensation in 2020 than in 2019.

Base Salary

Our compensation committee generally reviews base salaries in the fourthfirst quarter of the preceding fiscal year with adjusted salaries becoming effective retroactively as of January 1 of the following fiscal year. In addition to considering the peer group and/or other survey market data, the compensation committee also considers, among other factors, our performance, stock price appreciation, individual performance, experience, and the breadth of each position’s role.

When determining Drs. Cooper and Mauney’s 2019the 2020 base salaries of our named executive officers, the compensation committee considered 20182019 performance, that the base salaries of Dr. Cooper’s base salary had notCooper, Mr. Hadfield and Dr. de Groot were increased since he joined the Companysignificantly in 20152019 and that Dr. Mauney had been recently promoted to President earlier inMr. Shukla’s salary was below the year.2019 peer group data. These factors played a role in the compensation committee’s determination not to increase Drs.Dr. Cooper’s base salary and Mauney’s salaries by 14.6% and 10.0%, respectively. The compensation committee determined to increase the base salaries of Messrs.Mr. Hadfield and LafondDr. de Groot by 5.7% and 2.4%, respectively,only 2.0%. The compensation committee increased the base salary of Mr. Shukla’s by 5.1% to position their salarieshis salary near the middle of market data. As noted above, Dr. Baffa was hired in 2020, and therefore, Dr. Baffa was not eligible for an increase in his base salary in 2020.

Annual Incentive Compensation.

An important component of our total compensation program is the annual cash incentive, which is based on the achievement of annual company performance objectives and individual executive performance. Our compensation committee recognizes the important role that variable cash compensation plays in attracting and retaining executives, as well as focusing executives (and all other employees) on the achievement of key annual financial, research, clinical, business development and individual goals.

The compensation committee generally places a significant amount of our named executive officer’sofficers’ target cash compensation at risk and tied to achievement of our performance goals. This also serves as an important incentive and retention purpose in the highly competitive Greater Boston/Cambridge, Massachusetts area and national and international biopharmaceutical and biotechnology employment marketplace within which we compete for top executive talent. The 20192020 target bonus amountsamount for Dr. Cooper iswas specified in his employment agreement with the Company and is the same percentage of his salary as it was in 2018. The compensation committee increased Dr. Mauney’s target bonus percentage from 40% to 45% as a result of his promotion to President and increased Mr. Hadfield’s target bonus percentage from 30% to 40% as a result of Mr. Hadfield’s increased responsibility within the Company and in order to align Mr. Hadfield’s target bonus percentage with other executives within the Company. The 2019 target bonus amounts for Mr. Lafond remained unchanged from 2018 levels2019. The 2020 target bonus as a percentagepercent of base salary as the compensation committee determined that suchfor Mr. Shukla, Mr. Hadfield and Dr. de Groot was 40%, which remained unchanged from 2019 levels, continued to providereflecting competitive and adequate performance incentives and were competitive and reflective ofincentive consistent with his or her level of responsibility for attaining our corporate performance objectives. As noted above, Dr. Baffa was hired in 2020 and his target bonus as a percent of base salary is also 40% as specified in his employment agreement with the Company.

20192020 Annual Performance Objectives

In the first quarter of each year, the compensation committee,board of directors, in consultation with management, establishes Company goals that are used to assess management’s performance during the year. The Company goals are directed toward the advancement of our Cell Therapy and Controlled IL-12 and Cell Therapy platforms and other corporate or business development activities and financial objectives. Our BoardThe board of directors had the discretion under the 20192020 annual cash incentive program to adjust upward or downward any cash incentive award and/or the bonus pool as it deemed appropriate, including for qualitative factors such as degree of success, timing of achievement, and developments and achievements not contemplated at the time the performance goals were established.

During the year, the board of directors approved modest changes to the goals for the Controlled IL-12 platform as a result of a shift in our strategic priorities. The board of directors did not make any adjustments to our objectives as a result of the impact of the ongoing COVID-19 pandemic.

The table below describes the objectives established for 2019,2020, along with the compensation committee’s and Board’sboard of directors’ assessment of our achievement of these objectives:

For the past several years, we have granted our executive officers restricted stock because it was less dilutive to our stockholders than stock options, as fewer shares of our common stock are granted to achieve an equivalent value relative to stock options. In January 2019,2020, the Board elected to grantboard of directors granted a mix of restricted stock awards and stock options, with the intended mix roughly 50% in options and 50% in restricted stock to provide both an immediate retention incentive and to reward stock price growth through options.stock. The compensation committee determined this mix of options and restricted stock provided the appropriate balance to retain and incentivize our named executive officers and align the named executive officers’ interests with those of our stockholders. The Board believes this practice is more in line with our peers and,board of directors views the restricted stock as an immediate retention incentive, while it will likely increase the dilution to our stockholders, provides greater alignment betweenviews options as aligning our executives and stockholders with long-term success because our executives will only realize value with respect to the stock options if the value of our shares increases after the date of grant and the executive remains with us over the multi-year vesting period. The grant date values for the stock options and restricted stock are not equivalent as a result of changes in our stock price and accounting assumptions required to report such values under SEC rules.

In January 2019,2020, after referencing the 20182019 peer group data, the compensation committee granted the following equity awards to our named executive officers, with the exception of Dr. Baffa, that it believed to be competitive with the peer group and continue to align our executives’ interests with those of our stockholders in order to motivate their performance to increase our share value:value. As part of our negotiations with Dr. Baffa in connection with his commencement of employment, in November 2020, we granted him a stock option to purchase 500,000 shares of our common stock and issued Dr. Baffa 200,000 shares of restricted common stock. Grant values to the named executive officers who were not hired during 2020 were below the median of the peers, except that the grant value provided to Dr. de Groot was approximately consistent with the median.

Upon Mr. Shukla joining the Company in July 2019, Mr. Lafond ceased to be a member of our leadership team and, consistent with our historical practice for non-executive officers, Mr. Lafond received his 2020 equity incentive award, reflected below, in December 2019 rather than in January 2020 when our executive officers received their 2020 equity incentive awards. As a result of Mr. Lafond’s status change from executive officer to non-executive officer during 2019 and the difference in grant timing for our executive and non-executive equity awards, the Summary Compensation Table reflects equity awards for both 2019 and 2020 for Mr. Lafond.

Each of the restricted stock and stock options described above that were granted to our named executive officers vest in three equal annual installments and the stock options vest quarterly in equal installments over three years. Vesting of all awards is subject to continued service. These vesting schedules are designed to promote retention and encourage executives to consider the long-term stock price effects of their decisions.

Executive Retention

Our practice isIn November 2020, the board of directors recognized the need to grant new employees stock options, rather than restricted stock, that vest over four years. As partencourage key executives to remain employed with the Company to execute on our critical corporate goals. The retention risk was the result of the activist campaign initiated by Watermill, our limited ability to raise additional capital in light of the limited shares available for issuance under our certificate of incorporation, and the expected additional changes to our programs in light of our negotiationsresulting capital constraints.

In November 2020, the board of directors, following the recommendation of the compensation committee, granted each of Dr. de Groot and Messrs. Hadfield and Shukla a cash retention award in the amount of $500,000, with 40% of the retention award payable if such individual remains employed with us on April 1, 2021, 35% of the retention award payable if such individual remains employed with us on September 1, 2021, and 25% of the retention award payable if such individual remains employed with us on December 1, 2021. In addition, the board granted Dr. Baffa a cash retention award in the amount of $250,000, with 40% of the retention award payable if Dr. Baffa remains employed with us on April 1, 2021, 30% of the retention award payable if Dr. Baffa remains employed with us on September 1, 2021, and 30% of the retention award payable if Dr. Baffa remains employed with us on December 1, 2021. The final payment of the retention awards for each of Drs. Baffa and de Groot and Mr. Hadfield will only be payable if we achieve certain patient dosing milestones in our TCR-T