We have sent youYou are receiving this Proxy Statement and the enclosed proxy card (“Proxy CardCard”) because the board of directors (the “Board of Directors”) of Gritstone Oncology,bio, Inc. (referred to herein as the “Company,” “Gritstone,” “we,” “us” or “our”) is soliciting your proxy to vote at our 20212023 Annual Meeting of stockholders (the “Annual Meeting”) to be held on Friday, June 18, 2021,16, 2023, at 9:00 a.m. Pacific Time. The Annual Meeting can be accessed by visiting www.virtualshareholdermeeting.com/GRTS2021,GRTS2023, where you will be able to listen to the meeting live, submit questions and vote online.

In addition to solicitations by mail, our directors, officers and regular employees, without additional remuneration, may solicit proxies by telephone, e-mail and personal interviews. We may retain outside consultants to solicit proxies on our behalf as well. All costs of solicitation of proxies will be borne by us. Brokers, custodians and fiduciaries will be requested to forward proxy soliciting material to the owners of stock held in their names, and we will reimburse them for their reasonable out-of-pocket expenses incurred in connection with the distribution of proxy materials.

Pursuant to the rules adopted by the Securities and Exchange Commission (the “SEC”), we have elected to provide access to our Annual Meeting materials, which include this Proxy Statement and our Annual Report on Form 10-K for the year ended December 31, 20202022 (the “Form 10-K”), over the internet in lieu of mailing printed copies. We will begin mailing the Notice of Internet Availability to our stockholders of record as of the close of business on April 21, 202119, 2023 (the “Record Date”) for the first time on or about April 23, 2021.26, 2023. The Notice of Internet Availability will contain instructions on how to access and review the Annual Meeting materials and will also contain instructions on how to request a printed copy of the Annual Meeting materials. In addition, we have provided brokers, dealers, banks, voting trustees and their nominees, at our expense, with additional copies of our proxy materials and the Form 10-K so that our record holders can supply these materials to the beneficial owners of shares of our common stock as of the Record Date. The Form 10-K is also available in the “Investors & Media – SEC Filings” section of our website at http://www.gritstone.com.www.gritstonebio.com.

The only outstanding voting securities of Gritstone are shares of common stock, $0.0001 par value per share (the “common stock”), of which there were 49,197,82888,913,562 shares outstanding as of the Record Date (excluding any treasury shares). The holders of a majority in voting power of the shares of common stock issued and outstanding and entitled to vote, present in attendance online or represented by proxy, are required to hold the Annual Meeting.

We have made this Proxy Statement and Proxy Card available to you on the internet or, upon your request, have delivered printed proxy materials to you, because the boardBoard of directorsDirectors is soliciting your proxy to vote at the Annual Meeting, including at any adjournments or postponements of the Annual Meeting. You are invited to attend the Annual Meeting online to vote on the proposals described in this Proxy Statement. However, you are not required to attend the Annual Meeting to vote your shares. Instead, you may simply complete, sign and return the Proxy Card, or follow the instructions below to submit your proxy over the telephone or on the internet.

This Proxy Statement, the Notice of Internet Availability, the Notice of Annual Meeting and accompanying Proxy Card were first made available for access, by our stockholders on or about April 23, 202126, 2023, to all stockholders of record entitled to vote atas of the Annual Meeting.Record Date.

Only stockholdersHolders of recordour common stock at the close of business on April 19, 2023, the Record Date will befor the Annual Meeting, are entitled to notice of and to vote at the Annual Meeting. Each stockholder of record is entitled to one vote for each share of our common stock held as of the Record Date. At the close of business on the Record Date, there were 49,197,82888,913,562 shares of common stock issued and outstanding and entitled to vote.

If, on the Record Date, your shares were registered directly in your name with the transfer agent for our common stock, 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 by attending the Annual Meeting online and following the instructions posted at www.virtualshareholdermeeting.com/GRTS2021GRTS2023 or you may vote by proxy. Whether or not you plan to attend the Annual Meeting online, we encourage you to fill out and return the Proxy Card or vote by proxy over the telephone or on the internet as instructed below to ensure your vote is counted.

If, on the Record Date, your shares were held in an account at a brokerage firm, bank, dealer or other similar organization, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. The organization holding your account is considered the stockholder of record for purposes of voting at the Annual Meeting. As a beneficial owner, you have the right to direct your broker or other agent on how to vote the shares in your account. You are also invited to attend the Annual Meeting online at www.virtualshareholdermeeting.com/GRTS2021.GRTS2023. However, since you are not the stockholder of record, you may not vote your shares at the Annual Meeting by attending the Annual Meeting online unless you request and obtain a valid Proxy Card from your broker or other agent.

This year’s Annual Meeting will be held entirely online to allow greater participation and improved communication and provide cost savings for our stockholders and the Company. Stockholders of record as of the

We have engaged Broadridge Financial Solutions, Inc. (“Broadridge”) as our independent agent to tabulate stockholder votes or Inspector(the “Inspector of Election.Election”). If you are a stockholder of record, your executed Proxy Card is returned directly to Broadridge for tabulation. As noted above, if you hold your shares through a broker, your broker returns one Proxy Card to Broadridge on behalf of all its clients.

With respect to the election of directors (Proposal 1), you may vote “for” or “withhold” authority to vote for each of the nominees for the boardBoard of directors.Directors. If you “withhold” authority to vote with respect to one or more director nominees, your vote will have no effect on the election of such nominees. Broker non-votes will have no effect on the election of the nominees.

If we receive a signed and dated Proxy Card and the Proxy Card does not specify how your shares are to be voted, your shares will be voted “For” the election of each of the two nominees for director, and “For” the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm. If any other matter is properly presented at the Annual Meeting, your proxy (one of the individuals named on your Proxy Card) will vote your shares in his or her discretion.

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if the holders of a majority in voting power of the shares of common stock issued and outstanding and entitled to vote are present in attendance online or represented by proxy at the Annual Meeting. On the Record Date, there were 49,197,82888,913,562 shares outstanding and entitled to vote. Accordingly, 24,598,91544,456,782 shares must be represented by stockholders present at the Annual Meeting online or by proxy to have a quorum.

Your shares will be counted toward the quorum only if you submit a valid proxy or vote at the Annual Meeting. Abstentions and “Withhold” votes will be counted toward the quorum requirement. If there is no quorum, either the chair of the Annual Meeting or a majority in voting power of the stockholders entitled to vote at the Annual Meeting, in attendance online or represented by proxy, may adjourn the Annual Meeting to another time or place.

Our boardBoard of directorsDirectors is divided into three classes. Each class consists, as nearly as possible, of one-third of the total number of directors, and each class has a staggered, three-year term. Unless the boardBoard of directorsDirectors determines that vacancies (including vacancies created by increases in the number of directors) shall be filled by the stockholders, and except as otherwise provided by law, vacancies on the boardBoard of directorsDirectors may be filled only by the affirmative vote of a majority of the remaining directors. A director elected by the boardBoard of directorsDirectors to fill a vacancy (including a vacancy created by an increase in the number of directors) shall serve for the remainder of the full term of the class of directors in which the vacancy occurred and until such director’s successor is elected and qualified.

At each annual meeting of stockholders, the successors to directors whose terms will then expire will be elected to serve from the time of election and qualification until the third subsequent annual meeting of stockholders.

Steve KrognesDrs. Corey and Dr. Elaine JonesAgarwal have been nominated to serve as Class IIIII directors and have each elected to stand for reelection. Each director to be elected will hold office from the date of theirhis or her election by the stockholders until the third subsequent annual meeting of stockholders or until his or her successor is elected and has been qualified, or until such director’s earlier death, resignation or removal.

Shares represented by executed proxies will be voted, if authority to do so is not withheld, for the election of the two nominees named below. In the event that any nominee should be unavailable for election as a result of an unexpected occurrence, such shares will be voted for the election of such substitute nominee as the boardBoard of directorsDirectors may propose. Each person nominated for election has agreed to serve if elected, and management has no reason to believe that any nominee will be unable to serve. Directors are elected by a plurality of the votes cast at the meeting.

The following table sets forth, for the Class IIIII nominees (who are currently standing for re-election) and for our other current directors who will continue in office after the Annual Meeting, information with respect to their ages as of April 21, 202119, 2023 and position/office held within the Company:

We believe that Mr. KrognesDr. Agarwal is qualified to serve on our boardBoard of directorsDirectors due to hisher educational background and her experience as a board member and senior executive of biotechnology and pharmaceutical companies.

We believe that Dr. Jones is qualified to serve on our boardBoard of directorsDirectors due to her educational background, her knowledge of the pharmaceutical industry, her experience as a board member of biotechnology and pharmaceutical companies, and her experience as an investor in new life sciences companies.

We believe that Dr. Allen is qualified to serve on our boardBoard of directorsDirectors due to his educational experience and his experience as a senior executive of public and private biotechnology and pharmaceutical companies, including his service as our chief executive officer.Chief Executive Officer and President.

We believe that Ms. LiDr. Rizvi is qualified to serve on our board of directors due to her experience as a board member of biotechnology and pharmaceutical companies, and her experience as an investor in new life sciences companies.

The audit committee of our boardBoard of directorsDirectors has engaged Ernst & Young LLP (“EY”), as our independent registered public accounting firm for the year ending December 31, 2021,2023, and is seeking ratification of such selection by our stockholders at the Annual Meeting. EY has audited our financial statements for each of our fiscal years since the fiscal year ended December 31, 2015. Representatives of EY are expected to be in attendance online at the Annual Meeting. They will have an opportunity to make a statement if they so desire and will be available to respond to appropriate questions.

Nothing in our bylaws or other governing documents, or in any applicable law, requires stockholder ratification of the selection of EY as our independent registered public accounting firm. However, the audit committee is submitting the selection of EY to our stockholders for ratification as a matter of good corporate practice. If our stockholders fail to ratify the selection, the audit committee will reconsider whether or not to retain EY. Even if the selection is ratified, the audit committee in its discretion may direct the appointment of a different independent registered public accounting firm at any time during the year if they determine that such a change would be in the best interests of the Company and our stockholders.

The following table provides information regarding the fees incurred to EY during the years ended December 31, 20202022 and 2019.2021. The audit committee approved all of the fees described below and incurred since our initial public offering (“IPO”) in October 2018.the respective periods.

The audit committee, or a delegate of the audit committee, pre-approves, or provides pursuant to pre-approvals, policies and procedures for the pre-approval of, all audit and non-audit services provided by its independent registered public accounting firm. This policy is set forth in the charter of the audit committee and is available at http://www.gritstone.com.www.gritstonebio.com.

The audit committee approved all of the audit, audit-related, tax and other services provided by EY for 2019 and alleach of the audit, audit-related, taxyears ended December 31, 2022 and other services provided by EY in 20202021 and, in each case, the estimated costs of thosesuch services. Actual amounts billed, to the extent in excess of the estimated amounts, are periodically reviewed and approved by the audit committee.

The primary purpose of the audit committee is to oversee our financial reporting processes on behalf of our boardBoard of directors.Directors. The audit committee’s functions are more fully described in its charter, which is available on our website at http://www.gritstone.com.www.gritstonebio.com. Management has the primary responsibility for our consolidated financial statements and reporting processes, including our systems of internal controls. In fulfilling its oversight responsibilities, the audit committee reviewed and discussed with management Gritstone’s audited consolidated financial statements as of and for the year ended December 31, 2020.2022.

The audit committee has discussed with Ernst & Young LLP (“EY”), the Company’s independent registered public accounting firm, the matters required to be discussed by the applicable requirements of the Public Company Accounting Oversight Board (“PCAOB”) and the Securities and Exchange Commission (“SEC”). In addition, the audit committee discussed with EY their independence and received from EY the written disclosures and the letter required by Ethics and Independence Rule 3526 of the PCAOB. Finally, the audit committee discussed with EY, with and without management present, the scope and results of EY’s audit of such financial statements.

Based on these reviews and discussions, the audit committee has recommended to our boardBoard of directorsDirectors that such audited consolidated financial statements be included in our Annual Report on Form 10-K for the year ended December 31, 20202022 for filing with the SEC. The audit committee also has engaged EY as our independent registered public accounting firm for the fiscal year ending December 31, 20212023 and is seeking ratification of such selection by the stockholders.

We have adopted a code of business conduct and ethics that applies to all of our employees, officers and directors, including those officers responsible for financial reporting. The code of business conduct and ethics is available on our website at http://www.gritstone.com.www.gritstonebio.com. Any amendments to the code, or any waivers of its requirements, will be disclosed on our website.

We believe in sound corporate governance practices and have adopted formal corporate governance guidelines to enhance our effectiveness. Our boardBoard of directorsDirectors adopted these corporate governance guidelines in order to ensure that it has the necessary practices in place to review and evaluate our business operations as needed and to make decisions that are independent of our management. The corporate governance guidelines are also intended to align the interests of directors and management with those of our stockholders. The corporate governance guidelines set forth the practices our boardBoard of directorsDirectors follows with respect to boardBoard of directorsDirectors and committee composition and selection, meetings of the boardBoard of directors,Directors, Chief Executive Officer performance evaluation and succession planning. A copy of our corporate governance guidelines is available on our website at http://www.gritstone.com.www.gritstonebio.com.

As required under theThe Nasdaq Global Select MarketMarket’s (“Nasdaq”) rules and regulations, a majority of the members of a listed company’s board of directors must qualify as “independent,” as affirmatively determined by such board. The boardBoard of directorsDirectors consults with the Company’s counsel to ensure that the boardBoard of directors’Directors’ determinations are consistent with all relevant securities and other laws and regulations regarding the definition of “independent,” including those set forth in pertinent Nasdaq listing standards, as in effect from time to time.

Consistent with these considerations, our boardBoard of directorsDirectors has determined that all of our directors, other than Dr. Allen, qualify as “independent” directors in accordance with the Nasdaq listing requirements. Dr. Allen is not considered independent because he is an employee of Gritstone. The Nasdaq independence definition includes a series of objective tests, such as that the director is not, and has not been for at least three years, one of our employees and that neither the director nor any of his or her family members has engaged in various types of business dealings with us. In addition, as required by Nasdaq rules, our boardBoard of directorsDirectors has made a subjective determination as to each independent director that no relationships exist, which, in the opinion of our boardBoard of directors,Directors, would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In making these determinations, our boardBoard of directorsDirectors considered information provided by the directors and us with regard to each director’s business and personal activities and relationships as they may relate to us and our management. There are no family relationships among any of our directors or executive officers.

As required under Nasdaq rules and regulations, our independent directors meet in regularly scheduled executive sessions at which only independent directors are present. All of the committees of our boardBoard of directorsDirectors are comprised entirely of directors determined by the boardBoard of directorsDirectors to be independent within the meaning of Nasdaq and SEC rules and regulations applicable to the members of such committees.

Our bylaws and corporate governance guidelines provide our boardBoard of directorsDirectors with flexibility to combine or separate the positions of chair of the boardBoard of directorsDirectors and Chief Executive Officer and to implement a lead director in accordance with its determination that utilizing one or the other structure would be in the best interests of the Company. In the past, while we may not have formally appointed a chair or lead independent director, the board of directors generally did haveOfficer. Since May 2020, Elaine Jones, Ph.D., who is considered an independent director, presidehas served as chairperson of our Board of Directors. Dr. Jones presides over itsour executive sessions and actacts as a liaison between our management and the boardBoard of directors. Since May 2020, Elaine V. Jones, Ph.D., has performed these functions as chair of our board of directors.Directors.

Our boardBoard of directorsDirectors has concluded that our current leadership structure is appropriate at this time. However, our boardBoard of directorsDirectors will continue to periodically review our leadership structure and may make such changes in the future as it deems appropriate.

Our boardBoard of directorsDirectors does not have a standing risk management committee, but rather administers this oversight function directly through our boardBoard of directorsDirectors as a whole, as well as through various standing committees of our boardBoard of directorsDirectors that address risks inherent in their respective areas of oversight. In particular, our boardBoard of directorsDirectors is responsible for monitoring and assessing strategic risk exposure, and our audit committee is responsible for overseeing our major financial risk exposures and the steps our management has taken to monitor and control these exposures. The audit committee also monitors compliance with legal and regulatory requirements. Our nominating and governance committee monitors the effectiveness of our corporate governance guidelines and considers and approves or disapproves any related-person transactions. Our compensation committee assesses and monitors whether any of our compensation policies and programs has the potential to encourage excessive risk-taking.

Our audit committee oversees our corporate accounting and financial reporting process. Among other matters, the audit committee:

Our compensation committee oversees policies relating to compensation and benefits of our officers and employees other than our Chief Executive Officer, with respect to whom our boardBoard of directorsDirectors retains the authority to make compensation decisions. The compensation committee reviews and approves or recommends corporate goals and objectives relevant to compensation of our executive officers (other than our Chief Executive Officer), evaluates the performance of these officers in light of those goals and objectives and approves the compensation of these officers based on such evaluations. The compensation committee also reviews and approves or makes recommendations to our boardBoard of directorsDirectors regarding the issuance of stock options and other awards under our stock plans to our executive officers (other than our Chief Executive Officer). The compensation committee also reviews the performance of our Chief Executive Officer and makes recommendations to our boardBoard of directorsDirectors with respect to his compensation, while the boardBoard of directorsDirectors as a whole makes any final decisions. The compensation committee will review and evaluate, at least annually, the performance of the compensation committee and its members, including compliance by the compensation committee with its charter. The current members of our compensation committee are Mr. Krognes and Drs. WoiwodeAgarwal and Heyman and Mr. Krognes.Jones. Dr. WoiwodeAgarwal serves as the chairperson of theour compensation committee. Each of the membersmember of our compensation committee is independent under the applicable rules and regulations of Nasdaq and is a “non-employee director” as defined in Rule 16b-3 promulgated under the Exchange Act. The compensation committee operates under a written charter that satisfies the applicable standards of the SEC and Nasdaq. A copy of the compensation committee charter is available on the Company’s website at http://www.gritstone.com.www.gritstonebio.com.

Our compensation committee has retained Radford, Inc.the Human Capital Solutions subdivision of Aon plc (“Radford”Aon”), a national compensation consulting firm, to serve as its independent compensation consultant and to conduct market research and analysis on our various executive positions, to assist the committee in developing appropriate incentive plans for our executives on an annual basis, to provide the committee with advice and ongoing recommendations regarding material executive compensation decisions, and to review compensation proposals of management. RadfordAon reports directly to the compensation committee and does not provide any non-compensation related services to the Company. The compensation committee reviewed the independence of Radford,Aon, employing the independence factors specified in the listing requirements of Nasdaq. Based on this assessment, the compensation committee determined that the engagement of RadfordAon does not raise any conflicts of interest or similar concerns. In addition, the compensation committee evaluated the independence of its other outside advisors, including outside legal counsel, considering the same independence factors, and concluded that their work for the compensation committee does not raise any conflicts of interest.

The nominating and corporate governance committee is responsible for making recommendations to our boardBoard of directorsDirectors regarding candidates for directorships and the size and composition of our boardBoard of directors.Directors. In addition, the nominating and corporate governance committee is responsible for overseeing our corporate governance policies and reporting and making recommendations to our boardBoard of directorsDirectors concerning governance

Our nominating and corporate governance committee is responsible for reviewing with the boardBoard of directors,Directors, on an annual basis, the appropriate characteristics, skills and experience required for the boardBoard of directorsDirectors as a whole and its individual members. In evaluating the suitability of individual candidates (both new candidates and current members), the nominating and corporate governance committee, in recommending candidates for election, and the boardBoard of directors,Directors, in approving (and, in the case of vacancies, appointing) such candidates, may take into account many factors, including but not limited to the following:

Currently, our boardBoard of directorsDirectors evaluates each individual in the context of the boardBoard of directorsDirectors as a whole, with the objective of assembling a group that can best maximize the success of the business and represent stockholder interests through the exercise of sound judgment using its diversity of experience in these various areas.

During 2020,the year ended December 31, 2022, (i) our boardBoard of directorsDirectors met twelvethirteen (13) times, the(i) our audit committee met four (4) times, the(iii) our compensation committee met four (4) times, and the(iv) our nominating and corporate governance committee met four times. During 2020,three (3) times and (v) each member of the boardBoard of directorsDirectors attended at least 75% of the meetings of the boardBoard of directorsDirectors and of the committees of the boardBoard of directorsDirectors on which he or she served. We encourage all of our directors and nominees for director to attend our annual meeting of stockholders.

Should stockholders wish to communicate with the boardour Board of directorsDirectors or any specified individual director, such correspondence should be sent to the attention of the Corporate Secretary, at 5959 Horton Street, Suite 300, Emeryville, CA 94608. The Corporate Secretary will forward the communication to the boardBoard of directors.Directors.

DuringFrom January 1 to August 12, 2022, the year ended December 31, 2020, Thomas Woiwode, Ph.D., Richard Heyman, Ph.D., and Steve Krognes served as members of our compensation committee were Dr. Richard Heyman (who also served as chairperson of the committee), Mr. Steve Krognes and theyDr. Shefali Agarwal; following Dr. Heyman’s resignation from the Board, effective August 12, 2022, Dr. Agarwal became chairperson of our compensation committee. Effective September 27, 2022, Dr. Elaine Jones was appointed as a member of our compensation committee. Drs. Agarwal and Jones and Mr. Krognes continue to serve in that capacity.on the compensation committee. Dr. Agarwal serves as the chairperson of the committee. None of themthe members of the compensation committee has at any time been one of our officers or employees. None of our executive officers currently serves or in the past fiscal year has served, as a member of the boardBoard of directorsDirectors or compensation committee of any entity that has one or more executive officers on our boardBoard of directorsDirectors or compensation committee.

Our Insider Trading Compliance Policy prohibits our officers, directors, employees and specified consultants (and members of their immediate family or household) from engaging in hedging transactions involving our equity securities, including but not limited to zero-cost collars and forward sale contracts, and from engaging in short sales or transactions in puts, calls, or other derivative securities involving Gritstone’sour equity securities. In addition, our Insider Trading Compliance Policy prohibits these individuals from pledging Gritstoneour securities as collateral to secure loans. This prohibition means, among other things, that these individuals may not hold Gritstoneour securities in a “margin account,” which would allow the individual to borrow against their holdings to buy securities.

The following is a description of transactions since January 1, 20202022 to which we have been a party, in which the amount involved exceeds $120,000, and in which any of our directors, executive officers or beneficial owners of more than 5% of our capital stock, or an affiliate or immediate family member thereof, had or will have a direct or indirect material interest.

In December 2020,October 2022, we entered intocompleted a private placement transactionstransaction (the “PIPE“2022 PIPE Financing”), pursuant to which we sold an aggregate of 6,637,165 shares of our common stock at a per share purchase price of $2.26 and pre-funded warrants to purchase 13,274,923 shares of common stock at a price of $2.26 per share (of which $2.2599 per share was prepaid by each purchaser). As a result of the 2022 PIPE Financing, we received aggregate net proceeds of approximately $42.4 million after deducting placement agent commissions and offering expenses payable by the Company. In connection with the 2022 PIPE Financing, on November 22, 2022, we filed a registration statement on Form S-3 with the SEC registering the resale of all shares of our common stock that may be issued in the 2022 PIPE Financing.

Immediately prior to the closing of the 2022 PIPE Financing, certain existing and new investors, includingentities affiliated with Redmile Group, LLC were the beneficial owners of, in the aggregate, more than 5% of our capital stock. In connection with the 2022 PIPE financing, certain of such entities purchased pre-funded warrants to purchase 13,274,923 shares of our common stock at a price per share of $2.26, of which $2.2599 per share was prepaid by such entities in an aggregate amount of $29,999,998.49. No other beneficial owners of more than 5% of our capital stock and entities affiliated with certain of our directors. Pursuant to thisparticipated in the 2022 PIPE Financing, we sold (i) an aggregate of 5,543,351 shares of common stock at a per share purchase price of $3.34, (ii) pre-funded warrants to purchase an aggregate of 27,480,719 shares of common stock, each with an exercise price of $3.34 per share of common stock (of which $3.33 per share was pre-paid by each purchaser), and (iii) an aggregate of 4,043,127 shares of common stock at a per share purchase price of $3.71. The aggregate gross cash proceeds to Gritstone for the securities sold in this PIPE Financing was $125.0 million. The table below sets forth the number of shares of common stock and shares of common stock subject to pre-funded warrants sold to owners of more than 5% of our capital stock, or an affiliate or immediate family member thereof:Financing.

See “Executive Compensation”“Executive Compensation” and “Director Compensation”“Director Compensation” for information regarding compensation of directors and executive officers.

We have entered into employment agreements with our executive officers. For more information regarding these agreements, see “Executive“Executive Compensation—Narrative to Summary Compensation Table and Outstanding Equity Awards at 20202022 Fiscal Year End.End.”

The following table sets forth certain information about our executive officers of Gritstone are set forth below withand their respective ages as of April 21, 2021:19, 2023:

The following biographical information is furnished with regardrespect to our executive officers (except foras of as of April 19, 2023. For the biography of Dr. Allen, whose biographical information appears above under “Directorssee “Proposal No.1: Election of Directors— Directors Continuing in Office Until the 20222025 Annual Meeting of Stockholders”)Stockholders”.

This section discusses the material components of the executive compensation program for our “named executive officers” in the “Summary Compensation Table” below. Our named executive officers in 2020,2022, and their positions, arewere as follows:

As an “emerging growth company” as defined in the JOBS Act, we are not required to include a Compensation Discussion and Analysis section and have elected to comply with the scaled disclosure requirements applicable to emerging growth companies.

The following table provides information regarding thecash and equity compensation of our named executive officers for the fiscal years presented.

The following table provides information regarding equity awards held by our named executive officers as of December 31, 2020.2022.

Our named executive officers each receive a base salary to compensate them for services rendered to the Company. The base salary payable to each named executive officer is intended to provide a fixed component of compensation reflecting the executive’s skill set, experience, role and responsibilities.

Effective March 1, 2020,2022, Dr. Allen’s annual base salary was $575,000,$625,000, Dr. Yelensky’sJooss’ base salary was $402,065,$500,000, and Mr. Jones’ base salary was $380,397.$450,000. The base salary amounts actually paid in fiscal year 20202022 are set forth above in the Summary Compensation Table in the column titled “Salary.”

We maintain an annual performance-based cash bonus program in which each of our named executive officers participated in 2020.2022. Each named executive officer’s target bonus is expressed as a percentage of base salary which can be achieved by meeting certain corporate goals established by our board of directors and subject to downward discretion. The 20202022 annual bonuses for Dr. Allen, Dr. Yelensky,Jooss and Mr. Jones, which were paid out in February 2023, were originally targeted at 50%, 40%, and 40% of their respective base salaries.

In early 2021,2023, our board of directors reviewed and approved the achievement of our 20202022 corporate goals at 105%. Our board of directors also increased Dr. Allen’s target annual bonus to 55% of his annual base salary,

The annual cash bonuses paid to each named executive officer for 20202022 performance are set forth above in the Summary Compensation Table in the column titled “Non-Equity Incentive Plan Compensation.Compensation” other than the retroactive adjustment to Dr. Allen’s target annual bonus and the discretionary adjustment to Mr. Jones’ annual bonus amount, each of which is set forth in the Summary Compensation Table in the column titled “Bonus.”

On February 20, 2020,January 31, 2022, our board of directors granted Dr. Allen, Dr. Yelensky,Jooss and Mr. Jones an option to purchase 275,000, 130,000,410,000, 165,600 and 140,000163,000 shares of our common stock, respectively. Each option has an exercise price per share equal to $8.91,$5.46, which was the closing trading price of our common stock on the date of grant.

We maintain a 401(k) retirement savings plan for our employees, including our named executive officers, who satisfy certain eligibility requirements. Our named executive officers are eligible to participate in the 401(k) plan on the same terms as other full-time employees. Currently, we may match (in our discretion) contributions made by participants in the 401(k) plan in the amount equal to 50% ofdollar-for-dollar up to 4% of the participant’s eligible compensation contributed to the plan, not to exceed 2% of a participant’s eligible compensation.plan. We believe that providing a vehicle for tax-deferred retirement savings though our 401(k) plan adds to the overall desirability of our executive compensation package and further incentivizes our employees, including our named executive officers, in accordance with our compensation policies.

All of our full-time employees, including our named executive officers, are eligible to participate in our health and welfare plans, including medical, dental and vision benefits; medical and dependent care flexible spending accounts; short-term and long-term disability insurance; and life and AD&D insurance.

We provide limited perquisites to our named executive officers when our compensation committee determines that such perquisites are necessary or advisable to fairly compensate or incentivize our employees.

Our Amended and Restated Non-Employee Director Compensation Program as amended in February 2020,sets forth cash and equity compensation provided to our non-employee directors.

Under our Amended and Restated Non-Employee Director Compensation Program, our non-employee directors receiveare entitled to the following (i) annual cash retainer for their service on the Board and (ii) additional annual retainers for serving as non-executive chairperson and for their service on the committees of the Board:

Cash compensation is paid quarterly in arrears promptly following the end of the applicable calendar quarter, but in no event more than 30 days after the end of such quarter. In the event a non-employee director does not serve as follows:a non-employee director, or in the applicable position(s) described above, for an entire calendar quarter, the annual cash retainer and fees paid to such non-employee director is prorated for the portion of such calendar quarter actually served as a non-employee director, or in such position(s), as applicable.

Each non-employee director receives an annual cash retainer inwho is initially elected or appointed to serve on our Board is granted a stock option award under our 2018 Plan (or any other applicable equity incentive plan then-maintained by us) to purchase 38,000 shares of our Common Stock (such initial stock option award, the amount of $40,000 per year.“Initial Stock Option Grant”).

The chairperson ofInitial Stock Option Grant is automatically granted on the board of directors receives an additional annual cash retainer in the amount of $30,000 per year fordate on which such chairperson’s service presiding over the executive sessions of the board of directors and acting as a liaison between management and the board of directors.

The chairperson of the nominating and corporate governance committee receives additional annual cash compensation in the amount of $8,000 per year for such chairperson’s service on the nominating and corporate governance committee. Each non-chairperson member of the nominating and corporate governance committee receives additional annual cash compensation in the amount of $4,000 per year for such member’s service on the nominating and corporate governance committee.

The Initial GrantAnnual Stock Option Award is automatically granted on the date of the applicable Annual Meeting and will vest in substantially equal monthly installments for three years from the date of grant, subject to continued service through each applicable vesting date. The Annual Grant will vestfull on the earlier of (i) the first anniversary of the date of grant orand (ii) immediately prior to the Annual Meeting following the date of grant, subject to the next annual stockholder’s meetingnon-employee director continuing in service on the Board through such vesting date.

The per share exercise price of each of the Initial Stock Option Grant and the Annual Stock Option Grant equals the fair market value of a share of our common stock on the date any such option is granted and is determined pursuant to our 2018 Plan (or any other applicable equity incentive plan then-maintained by us to the extent unvested as of such date, subject to continued service through each applicable vesting date.

The following table presents information as to the beneficial ownership of our common stock as of April 21, 2021March 31, 2023 for:

Beneficial ownership is determined in accordance with the SEC rules of the SEC and generally includes voting or investment power with respect to our securities. Unless otherwise indicated below, to our knowledge, the persons and entities named in the table have sole voting and sole investment power with respect to all shares beneficially owned, subject to community property laws where applicable. Shares of our common stock subject to options that are currently exercisable or exercisable within 60 days of April 21, 2021March 31, 2023 are deemed to be outstanding and to be beneficially owned by the person holding the options for the purpose of computing the percentage ownership of that person but are not treated as outstanding for the purpose of computing the percentage ownership of any other person.

The percentage of shares beneficially owned is computed on the basis of 49,197,82887,848,417 shares of our common stock outstanding as of April 21, 2021. ThisMarch 31, 2023. The table below is based upon information supplied to us by our executive officers, directors and principal stockholders and Schedules 13D and Schedules 13G, if any, filed with the SEC, as well as information provided to us by The Nasdaq Stock Market, LLC.

Unless otherwise indicated, the address of each of the individuals and entities named below is c/o Gritstone Oncology,bio, Inc., 5959 Horton Street, Suite 300, Emeryville, CA 94608.

Section 16(a) of the Exchange Act requires the Company’s directors and executive officers, and persons who own more than 10% of a registered class of the Company’s equity securities, to file with the SEC initial reports of ownership and reports of changes in ownership of common stock and other equity securities of the Company. Officers, directors and greater than 10% stockholders are required by SEC regulations to furnish the Company with copies of all Section 16(a) forms they file.

To the Company’s knowledge, based solely on a review of the copies of such reports furnished to the Company and written representations that no other reports were required, the Company believes that all Section 16(a) filing requirements applicable to our officers, directors and greater than 10% beneficial owners were complied with during the year ended December 31, 2020.2022, except that Form 4 filings for each of Rahsaan Thompson, Karin Jooss, Erin Jones, Matthew Hawryluk, Vassiliki “Celia” Economides, James Cho and Andrew Allen in connection with certain restricted stock units and options granted to each of the foregoing officers (and, in the case of Dr. Allen, officers and directors) on January 31, 2022 were filed late.

The SEC has adopted rules that permit companies and intermediaries (e.g., brokers) to satisfy the delivery requirements for proxy statements and annual reports with respect to two or more stockholders sharing the same address by delivering a single proxy statement addressed to those stockholders. This process, which is commonly referred to as “householding,” potentially means extra convenience for stockholders and cost savings for companies.

Brokers with account holders who are Gritstone stockholders may be “householding” our proxy materials. A single proxy statement may be delivered to multiple stockholders sharing an address unless contrary instructions have been received from the affected stockholders. Once you have received notice from your broker that it will be “householding” communications to your address, “householding” will continue until you are notified otherwise or until you notify your broker or the Company that you no longer wish to participate in “householding.”

If, at any time, you no longer wish to participate in “householding” and would prefer to receive a separate proxy statement and annual report, you may (1) notify your broker or (2) direct your written request to: 5959 Horton Street, Suite 300, Emeryville, CA 94608. Stockholders who currently receive multiple copies of this Proxy Statement at their address and would like to request “householding” of their communications should contact their broker. In addition, the Company will promptly deliver, upon written or oral request to the address or telephone number above, a separate copy of the Form 10-K, Proxy Statement, Proxy Card or Notice of Internet Availability of Proxy Materials to a stockholder at a shared address to which a single copy of the documents was delivered.

Notwithstanding anything to the contrary set forth in any of our previous filings under the Securities Act or the Exchange Act, which might incorporate future filings made by us under those statutes, the Audit Committee Report will not be incorporated by reference into any of those prior filings, nor will any such report be incorporated by reference into any future filings made by us under those statutes. In addition, information on our website, other than our proxy statement, notice and form of proxy, is not part of the proxy soliciting material and is not incorporated herein by reference.

As of the date of this Proxy Statement, the boardBoard of directorsDirectors does not intend to present any matters other than those described herein at the Annual Meeting and is unaware of any matters to be presented by other parties.

If other matters are properly brought before the Annual Meeting for action by the stockholders, proxies will be voted in accordance with the recommendation of the boardBoard of directorsDirectors or, in the absence of such a recommendation, in the discretion of the proxy holder.