Document:

EX-10.8

 Exhibit 10.8 

GRITSTONE ONCOLOGY, INC. 

2018 EMPLOYEE STOCK PURCHASE PLAN 

ARTICLE I. 
 PURPOSE

 The Plan’s purpose is to assist employees of the Company and its Designated Subsidiaries in acquiring a stock ownership interest
in the Company pursuant to a plan which is intended to qualify as an “employee stock purchase plan” under Section 423 of the Code, and to help such employees provide for their future security and to encourage them to remain in the
employment of the Company and its Subsidiaries. 
 ARTICLE II. 

DEFINITIONS 
 As used in
the Plan, the following words and phrases have the meanings specified below, unless the context clearly indicates otherwise: 

2.1     “Administrator” means the Committee, or such individuals to which authority to administer
the Plan has been delegated under Section 7.1 hereof. 
 2.2    “Agent” means the brokerage
firm, bank or other financial institution, entity or person(s), if any, engaged, retained, appointed or authorized to act as the agent of the Company or an Employee with regard to the Plan. 

2.3    “Board” means the Board of Directors of the Company. 

2.4    “Code” means the U.S. Internal Revenue Code of 1986, as amended, and all regulations,
guidance, compliance programs and other interpretative authority issued thereunder. 

2.5    “Committee” means the Compensation Committee of the Board. 

2.6    “Common Stock” means the common stock of the Company. 

2.7    “Company” means Gritstone Oncology, Inc., a Delaware corporation, or any successor. 

2.8    “Compensation” of an Employee means the regular earnings or base salary, bonuses and
commissions paid to the Employee from the Company on each Payday as compensation for services to the Company or any Designated Subsidiary, before deduction for any salary deferral contributions made by the Employee to any tax-qualified or nonqualified deferred compensation plan, including overtime, shift differentials, vacation pay, salaried production schedule premiums, holiday pay, jury duty pay, funeral leave pay, paid time off,
military pay, prior week adjustments and weekly bonus, but excluding education or tuition reimbursements, imputed income arising under any group insurance or benefit program, travel expenses, business and moving reimbursements, including tax gross
ups and taxable mileage allowance, income received in connection with any stock options, restricted stock, restricted stock units or other compensatory equity awards and all contributions made by the Company or any Designated Subsidiary for the
Employee’s benefit under any employee benefit plan now or hereafter established. Such Compensation shall be calculated before deduction of any income or employment tax withholdings, but shall be withheld from the Employee’s net income.

 2.9    “Designated Subsidiary” means each Subsidiary
that has been designated by the Board or Committee from time to time in its sole discretion as eligible to participate in the Plan, including any Subsidiary in existence on the Effective Date and any Subsidiary formed or acquired following the
Effective Date, in accordance with Section 7.2 hereof. 
 2.10    “Effective Date” means
the date immediately prior to the date the Company’s registration statement relating to its initial public offering becomes effective, provided that the Board has adopted the Plan prior to or on such date, subject to approval of the Plan
by the Company’s stockholders. 
 2.11     “Eligible Employee” means an Employee who: 

(a)    is customarily scheduled to work at least 20 hours per week; 

(b)    whose customary employment is more than five months in a calendar year; and 

(c)    after the granting of the Option would not be deemed for purposes of Section 423(b)(3) of the Code to possess
5% or more of the total combined voting power or value of all classes of stock of the Company or any Subsidiary. 
 For purposes of clause (c), the rules of
Section 424(d) of the Code with regard to the attribution of stock ownership shall apply in determining the stock ownership of an individual, and stock which an Employee may purchase under outstanding options shall be treated as stock owned by
the Employee. 
 Notwithstanding the foregoing, the Administrator may exclude from participation in the Plan as an Eligible Employee: 

(x)     any Employee that is a “highly compensated employee” of the Company or any Designated Subsidiary
(within the meaning of Section 414(q) of the Code), or that is such a “highly compensated employee” (A) with compensation above a specified level, (B) who is an officer or (C) who is subject to the disclosure requirements of
Section 16(a) of the Exchange Act; or 
 (y) any Employee who is a citizen or resident of a foreign jurisdiction (without regard to
whether they are also a citizen of the United States or a resident alien (within the meaning of Section 7701(b)(1)(A) of the Code)) if either (A) the grant of the Option is prohibited under the laws of the jurisdiction governing such
Employee, or (B) compliance with the laws of the foreign jurisdiction would cause the Plan or the Option to violate the requirements of Section 423 of the Code; 

provided that any exclusion in clauses (x) or (y) shall be applied in an identical manner under each Offering Period to all Employees of the
Company and all Designated Subsidiaries, in accordance with Treasury Regulation Section 1.423-2(e). 

2.12    “Employee” means any person who renders services to the Company or a Designated Subsidiary
in the status of an employee within the meaning of Section 3401(c) of the Code. “Employee” shall not include any director of the Company or a Designated Subsidiary who does not render services to the Company or a Designated Subsidiary
in the status of an employee within the meaning of Section 3401(c) of the Code. For purposes of the Plan, the employment relationship shall be treated as continuing intact while the individual is on military leave, sick leave or other leave of
absence 

  
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approved by the Company or a Designated Subsidiary and meeting the requirements of Treasury Regulation Section 1.421-1(h)(2). Where the period of
leave exceeds three months, or such other period specified in Treasury Regulation Section 1.421-1(h)(2), and the individual’s right to reemployment is not guaranteed either by statute or by contract,
the employment relationship shall be deemed to have terminated on the first day immediately following such three-month period, or such other period specified in Treasury Regulation Section 1.421-1(h)(2).

 2.13    “Enrollment Date” means the first date of each Offering Period. 

2.14    “Exercise Date” means the last Trading Day of each Offering Period, except as provided in
Section 5.2 hereof. 
 2.15    “Exchange Act” means the Securities Exchange Act of 1934, as
amended. 
 2.16    “Fair Market Value” means, as of any date, the value of Common Stock
determined as follows: 
 (a)    If the Common Stock is (i) listed on any established securities exchange (such as
the New York Stock Exchange, the NASDAQ Global Market or the NASDAQ Global Select Market), (ii) listed on any national market system or (iii) listed, quoted or traded on any automated quotation system, its Fair Market Value shall be the closing
sales price for a share of Common Stock as quoted on such exchange or system for such date or, if there is no closing sales price for a share of Common Stock on the date in question, the closing sales price for a share of Stock on the last preceding
date for which such quotation exists, as reported in The Wall Street Journal or such other source as the Administrator deems reliable; 

(b)    If the Common Stock is not listed on an established securities exchange, national market system or automated
quotation system, but the Common Stock is regularly quoted by a recognized securities dealer, its Fair Market Value shall be the mean of the high bid and low asked prices for such date or, if there are no high bid and low asked prices for a share of
Common Stock on such date, the high bid and low asked prices for a share of Common Stock on the last preceding date for which such information exists, as reported in The Wall Street Journal or such other source as the Administrator deems
reliable; or 
 (c)    If the Common Stock is neither listed on an established securities exchange, national market
system or automated quotation system nor regularly quoted by a recognized securities dealer, its Fair Market Value shall be established by the Administrator in good faith. 

2.17    “Grant Date” means the first Trading Day of an Offering Period. 

2.18     “New Exercise Date” has the meaning set forth in Section 5.2(b) hereof. 

2.19    “Offering Period” means such period of time commencing on such date(s) as determined by
the Board or Committee, in its sole discretion, and with respect to which Options shall be granted to Participants. The duration and timing of Offering Periods may be established or changed by the Board or Committee at any time, in its sole
discretion. Notwithstanding the foregoing, in no event may an Offering Period exceed 27 months. 

2.20    “Option” means the right to purchase shares of Common Stock pursuant to the Plan during
each Offering Period. 

  
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 2.21    “Option Price” means the purchase price of a
share of Common Stock hereunder as provided in Section 4.2 hereof. 
 2.22    “Parent”
means any entity that is a parent corporation of the Company within the meaning of Section 424 of the Code. 

2.23    “Participant” means any Eligible Employee who elects to participate in the Plan. 

2.24    “Payday” means the regular and recurring established day for payment of Compensation to an
Employee of the Company or any Designated Subsidiary. 
 2.25    “Plan” means this 2018 Employee
Stock Purchase Plan. 
 2.26    “Plan Account” means a bookkeeping account established and
maintained by the Company in the name of each Participant. 

2.27    “Section 423 Option” has the meaning set forth in
Section 3.1(b) hereof. 
 2.28    “Subsidiary” means any entity that is a subsidiary
corporation of the Company within the meaning of Section 424 of the Code. In addition, with respect to any sub-plans adopted under Section 7.1(d) hereof which are designed to be outside the scope of
Section 423 of the Code, Subsidiary shall include any corporate or noncorporate entity in which the Company has a direct or indirect equity interest or significant business relationship. 

2.29    “Trading Day” means a day on which the principal securities exchange on which the Common
Stock is listed is open for trading or, if the Common Stock is not listed on a securities exchange, means a business day, as determined by the Administrator in good faith. 

2.30    “Withdrawal Election” has the meaning set forth in Section 6.1(a) hereof. 

ARTICLE III. 

PARTICIPATION 

3.1    Eligibility. 

(a)    Any Eligible Employee who is employed by the Company or a Designated Subsidiary on a given Enrollment Date for an
Offering Period shall be eligible to participate in the Plan during such Offering Period, subject to the requirements of Articles IV and V hereof, and the limitations imposed by Section 423(b) of the Code. 

(b)    No Eligible Employee shall be granted an Option under the Plan which permits the Participant’s rights to
purchase shares of Common Stock under the Plan, and to purchase stock under all other employee stock purchase plans of the Company, any Parent or any Subsidiary subject to Section 423 of the Code (any such Option or other option, a
“Section 423 Option”), to accrue at a rate which exceeds $25,000 of fair market value of such stock (determined at the time the Section 423 Option is granted) for each calendar year in
which any Section 423 Option granted to the Participant is outstanding at any time. For purposes of the limitation imposed by this subsection: 

(i)    the right to purchase stock under a Section 423 Option accrues when the Section 423
Option (or any portion thereof) first becomes exercisable during the calendar year; 

  
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 (ii)    the right to purchase stock under a Section 423
Option accrues at the rate provided in the Section 423 Option, but in no case may such rate exceed $25,000 of fair market value of such stock (determined at the time such option is granted) for any one calendar year; and 

(iii)    a right to purchase stock which has accrued under a Section 423 Option may not be carried
over to any other Section 423 Option; provided that Participants may carry forward amounts so accrued that represent a fractional share of stock and were withheld but not applied towards the purchase of Common Stock under an earlier
Offering Period, and may apply such amounts towards the purchase of additional shares of Common Stock under a subsequent Offering Period. 
 The limitation
under this Section 3.1(b) shall be applied in accordance with Section 423(b)(8) of the Code. 

3.2    Election to Participate; Payroll Deductions 

(a)    Except as provided in Section 3.3 hereof, an Eligible Employee may become a Participant in the Plan only by
means of payroll deduction. Each individual who is an Eligible Employee as of an Offering Period’s Enrollment Date may elect to participate in such Offering Period and the Plan by delivering to the Company a payroll deduction authorization no
later than the period of time prior to the applicable Enrollment Date that is determined by the Administrator, in its sole discretion. 

(b)    Subject to Section 3.1(b) hereof, payroll deductions (i) shall be equal to at least 1% of the
Participant’s Compensation as of each Payday of the Offering Period following the Enrollment Date, but not more than 15% of the Participant’s Compensation as of each Payday of the Offering Period following the Enrollment Date; and
(ii) may be expressed either as (A) a whole number percentage, or (B) a fixed dollar amount. Amounts deducted from a Participant’s Compensation with respect to an Offering Period pursuant to this Section 3.2 shall be
deducted each Payday through payroll deduction and credited to the Participant’s Plan Account. 
 (c)    Following
at least one payroll deduction, a Participant may decrease (to as low as zero) the amount deducted from such Participant’s Compensation only once during an Offering Period upon ten calendar days’ prior written notice to the Company. A
Participant may not increase the amount deducted from such Participant’s Compensation during an Offering Period. 

(d)    Notwithstanding the foregoing, upon the termination of an Offering Period, each Participant in such Offering
Period shall automatically participate in the immediately following Offering Period at the same payroll deduction percentage or fixed amount as in effect at the termination of the prior Offering Period, unless such Participant delivers to the
Company a different election with respect to the successive Offering Period in accordance with Section 3.2(a) hereof, or unless such Participant becomes ineligible for participation in the Plan. 

3.3    Leave of Absence. During leaves of absence approved by the Company meeting the requirements of Treasury
Regulation Section 1.421-1(h)(2), a Participant may continue participation in the Plan by making cash payments to the Company on his or her normal payday equal to his or her authorized payroll deduction.

  
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 ARTICLE IV. 

PURCHASE OF SHARES 

4.1    Grant of Option. Each Participant shall be granted an Option with respect to an Offering Period on the
applicable Grant Date. Subject to the limitations of Section 3.1(b) hereof, the number of shares of Common Stock subject to a Participant’s Option shall be determined by dividing (a) such Participant’s payroll deductions
accumulated prior to an Exercise Date and retained in the Participant’s Plan Account on such Exercise Date by (b) the applicable Option Price; provided that in no event shall a Participant be permitted to purchase during each
Offering Period more than 15,000 shares of Common Stock (subject to any adjustment pursuant to Section 5.2 hereof). The Administrator may, for future Offering Periods, increase or decrease, in its absolute discretion, the maximum number of
shares of Common Stock that a Participant may purchase during such future Offering Periods. Each Option shall expire on the Exercise Date for the applicable Offering Period immediately after the automatic exercise of the Option in accordance with
Section 4.3 hereof, unless such Option terminates earlier in accordance with Article 6 hereof. 
 4.2    Option
Price. The “Option Price” per share of Common Stock to be paid by a Participant upon exercise of the Participant’s Option on the applicable Exercise Date for an Offering Period shall be equal to 85% of the lesser of
the Fair Market Value of a share of Common Stock on (a) the applicable Grant Date and (b) the applicable Exercise Date; provided that in no event shall the Option Price per share of Common Stock be less than the par value per share
of the Common Stock. 
 4.3    Purchase of Shares. 

(a)    On the applicable Exercise Date for an Offering Period, each Participant shall automatically and without any
action on such Participant’s part be deemed to have exercised his or her Option to purchase at the applicable per share Option Price the largest number of whole shares of Common Stock which can be purchased with the amount in the
Participant’s Plan Account. Any balance less than the per share Option Price that is remaining in the Participant’s Plan Account (after exercise of such Participant’s Option) as of the Exercise Date shall be carried forward to the
next Offering Period, unless the Participant has elected to withdraw from the Plan pursuant to Section 6.1 hereof or, pursuant to Section 6.2 hereof, such Participant has ceased to be an Eligible Employee. Any balance not carried forward
to the next Offering Period in accordance with the prior sentence promptly shall be refunded to the applicable Participant. For the avoidance of doubt, in no event shall an amount greater than or equal to the per share Option Price as of an Exercise
Date be carried forward to the next Offering Period. 
 (b)    As soon as practicable following the applicable Exercise
Date, the number of shares of Common Stock purchased by such Participant pursuant to Section 4.3(a) hereof shall be delivered (either in share certificate or book entry form), in the Company’s sole discretion, to either (i) the
Participant or (ii) an account established in the Participant’s name at a stock brokerage or other financial services firm designated by the Company. If the Company is required to obtain from any commission or agency authority to issue any
such shares of Common Stock, the Company shall seek to obtain such authority. Inability of the Company to obtain from any such commission or agency authority which counsel for the Company deems necessary for the lawful issuance of any such shares
shall relieve the Company from liability to any Participant except to refund to the Participant such Participant’s Plan Account balance, without interest thereon. 

4.4    Transferability of Rights. An Option granted under the Plan shall not be transferable, other than by will or
the applicable laws of descent and distribution, and is exercisable during the Participant’s lifetime only by the Participant. No option or interest or right to the Option shall be available to pay off any debts, contracts or engagements of the
Participant or his or her successors in 

  
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interest or shall be subject to disposition by pledge, encumbrance, assignment or any other means whether such disposition be voluntary or involuntary or by operation of law by judgment, levy,
attachment, garnishment or any other legal or equitable proceedings (including bankruptcy), and any attempt at disposition of the Option shall have no effect. 

ARTICLE V. 
 PROVISIONS
RELATING TO COMMON STOCK 
 5.1    Common Stock Reserved. Subject to adjustment as provided in
Section 5.2 hereof, the maximum number of shares of Common Stock that shall be made available for sale under the Plan shall be the sum of (a) 282,334 shares and (b) an annual increase on the first day of each year beginning in 2019 and
ending in 2028 equal to the lesser of (i) 1% of the shares outstanding (on an as converted basis) on the last day of the immediately preceding fiscal year and (ii) such number of shares as may be determined by the Board; provided,
however, no more than 5,000,000 shares may be issued under the Plan. Shares made available for sale under the Plan may be authorized but unissued shares, treasury shares of Common Stock, or reacquired shares reserved for issuance under the Plan.

 5.2    Adjustments Upon Changes in Capitalization, Dissolution, Liquidation, Merger or Asset Sale. 

(a)    Changes in Capitalization. Subject to any required action by the stockholders of the Company, the number of
shares of Common Stock which have been authorized for issuance under the Plan but not yet placed under Option, as well as the price per share and the number of shares of Common Stock covered by each Option under the Plan which has not yet been
exercised shall be proportionately adjusted for any increase or decrease in the number of issued shares of Common Stock resulting from a stock split, reverse stock split, stock dividend, combination or reclassification of the Common Stock, or any
other increase or decrease in the number of shares of Common Stock effected without receipt of consideration by the Company; provided, however, that conversion of any convertible securities of the Company shall not be deemed to have
been “effected without receipt of consideration.” Such adjustment shall be made by the Administrator, whose determination in that respect shall be final, binding and conclusive. Except as expressly provided herein, no issuance by the
Company of shares of stock of any class, or securities convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number or price of shares of Common Stock subject to an
Option. 
 (b)    Dissolution or Liquidation. In the event of the proposed dissolution or liquidation of the
Company, the Offering Period then in progress shall be shortened by setting a new Exercise Date (the “New Exercise Date”), and shall terminate immediately prior to the consummation of such proposed dissolution or liquidation,
unless provided otherwise by the Administrator. The New Exercise Date shall be before the date of the Company’s proposed dissolution or liquidation. The Administrator shall notify each Participant in writing, at least ten business days
prior to the New Exercise Date, that the Exercise Date for the Participant’s Option has been changed to the New Exercise Date and that the Participant’s Option shall be exercised automatically on the New Exercise Date, unless prior to such
date the Participant has withdrawn from the Offering Period as provided in Section 6.1 hereof. 
 (c)    Merger
or Asset Sale. In the event of a proposed sale of all or substantially all of the assets of the Company, or the merger of the Company with or into another corporation, each outstanding Option shall be assumed or an equivalent Option substituted
by the successor corporation or a Parent or Subsidiary of the successor corporation. In the event that the successor corporation refuses to assume or substitute for the Option, any Offering Periods then in progress shall be shortened by setting a
New Exercise Date and any Offering Periods then in progress 

  
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shall end on the New Exercise Date. The New Exercise Date shall be before the date of the Company’s proposed sale or merger. The Administrator shall notify each Participant in writing, at
least ten business days prior to the New Exercise Date, that the Exercise Date for the Participant’s Option has been changed to the New Exercise Date and that the Participant’s Option shall be exercised automatically on the New Exercise
Date, unless prior to such date the Participant has withdrawn from the Offering Period as provided in Section 6.1 hereof. 

5.3    Insufficient Shares. If the Administrator determines that, on a given Exercise Date, the number of shares of
Common Stock with respect to which Options are to be exercised may exceed the number of shares of Common Stock remaining available for sale under the Plan on such Exercise Date, the Administrator shall make a pro rata allocation of the shares of
Common Stock available for issuance on such Exercise Date in as uniform a manner as shall be practicable and as it shall determine in its sole discretion to be equitable among all Participants exercising Options to purchase Common Stock on such
Exercise Date, and unless additional shares are authorized for issuance under the Plan, no further Offering Periods shall take place and the Plan shall terminate pursuant to Section 7.5 hereof. If an Offering Period is so terminated, then the
balance of the amount credited to the Participant’s Plan Account which has not been applied to the purchase of shares of Common Stock shall be paid to such Participant in one lump sum in cash within 30 days after such Exercise Date, without any
interest thereon. 
 5.4    Rights as Stockholders. With respect to shares of Common Stock subject to an Option,
a Participant shall not be deemed to be a stockholder of the Company and shall not have any of the rights or privileges of a stockholder. A Participant shall have the rights and privileges of a stockholder of the Company when, but not until, shares
of Common Stock have been deposited in the designated brokerage account following exercise of his or her Option. 
 ARTICLE VI. 

TERMINATION OF PARTICIPATION 

6.1    Cessation of Contributions; Voluntary Withdrawal. 

(a)    A Participant may cease payroll deductions during an Offering Period and elect to withdraw from the Plan by
delivering written notice of such election to the Company in such form and at such time prior to the Exercise Date for such Offering Period as may be established by the Administrator (a “Withdrawal Election”). A Participant
electing to withdraw from the Plan may elect to either (i) withdraw all of the funds then credited to the Participant’s Plan Account as of the date on which the Withdrawal Election is received by the Company, in which case amounts credited
to such Plan Account shall be returned to the Participant in one lump-sum payment in cash within 30 days after such election is received by the Company, without any interest thereon, and the Participant shall
cease to participate in the Plan and the Participant’s Option for such Offering Period shall terminate; or (ii) exercise the Option for the maximum number of whole shares of Common Stock on the applicable Exercise Date with any remaining
Plan Account balance returned to the Participant in one lump-sum payment in cash within 30 days after such Exercise Date, without any interest thereon, and after such exercise cease to participate in the
Plan. Upon receipt of a Withdrawal Election, the Participant’s payroll deduction authorization and his or her Option to purchase under the Plan shall terminate. 

(b)    A participant’s withdrawal from the Plan shall not have any effect upon his or her eligibility to participate
in any similar plan which may hereafter be adopted by the Company or in succeeding Offering Periods which commence after the termination of the Offering Period from which the Participant withdraws. 

  
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 (c)    A Participant who ceases contributions to the Plan during any
Offering Period shall not be permitted to resume contributions to the Plan during that Offering Period. 

6.2    Termination of Eligibility. Upon a Participant’s ceasing to be an Eligible Employee, for any reason,
such Participant’s Option for the applicable Offering Period shall automatically terminate, he or she shall be deemed to have elected to withdraw from the Plan, and such Participant’s Plan Account shall be paid to such Participant or, in
the case of his or her death, to the person or persons entitled thereto pursuant to applicable law, within 30 days after such cessation of being an Eligible Employee, without any interest thereon. 

ARTICLE VII. 
 GENERAL
PROVISIONS 
 7.1    Administration. 

(a)    The Plan shall be administered by the Committee, which shall be composed of members of the Board. The Committee
may delegate administrative tasks under the Plan to the services of an Agent or Employees to assist in the administration of the Plan, including establishing and maintaining an individual securities account under the Plan for each Participant. 

(b)    It shall be the duty of the Administrator to conduct the general administration of the Plan in accordance with the
provisions of the Plan. The Administrator shall have the power, subject to, and within the limitations of, the express provisions of the Plan: 

(i)    To establish and terminate Offering Periods; 

(ii)    To determine when and how Options shall be granted and the provisions and terms of each Offering
Period (which need not be identical); 
 (iii)    To select Designated Subsidiaries in accordance with
Section 7.2 hereof; and 
 (iv)    To construe and interpret the Plan, the terms of any Offering
Period and the terms of the Options and to adopt such rules for the administration, interpretation, and application of the Plan as are consistent therewith and to interpret, amend or revoke any such rules. The Administrator, in the exercise of this
power, may correct any defect, omission or inconsistency in the Plan, any Offering Period or any Option, in a manner and to the extent it shall deem necessary or expedient to administer the Plan, subject to Section 423 of the Code. 

(c)    The Administrator may adopt rules or procedures relating to the operation and administration of the Plan to
accommodate the specific requirements of local laws and procedures. Without limiting the generality of the foregoing, the Administrator is specifically authorized to adopt rules and procedures regarding handling of participation elections, payroll
deductions, payment of interest, conversion of local currency, payroll tax, withholding procedures and handling of stock certificates which vary with local requirements. In its absolute discretion, the Board may at any time and from time to time
exercise any and all rights and duties of the Administrator under the Plan. 
 (d)    The Administrator may adopt sub-plans applicable to particular Designated Subsidiaries or locations, which sub-plans may be designed to be outside the scope of Section 423 of the Code. The rules of
such sub-plans may take precedence over other provisions of this Plan, with the exception of Section 5.1 hereof, but unless otherwise superseded by the terms of such sub-plan, the provisions of this Plan
shall govern the operation of such sub-plan. 

  
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 (e)    All expenses and liabilities incurred by the Administrator in
connection with the administration of the Plan shall be borne by the Company. The Administrator may, with the approval of the Committee, employ attorneys, consultants, accountants, appraisers, brokers or other persons. The Administrator, the Company
and its officers and directors shall be entitled to rely upon the advice, opinions or valuations of any such persons. All actions taken and all interpretations and determinations made by the Administrator in good faith shall be final and binding
upon all Participants, the Company and all other interested persons. No member of the Board or Administrator shall be personally liable for any action, determination or interpretation made in good faith with respect to the Plan or the options, and
all members of the Board or Administrator shall be fully protected by the Company in respect to any such action, determination, or interpretation. 

7.2    Designation of Subsidiary Corporations. The Board or Committee shall designate from among the Subsidiaries,
as determined from time to time, the Subsidiary or Subsidiaries that shall constitute Designated Subsidiaries. The Board or Committee may designate a Subsidiary, or terminate the designation of a Subsidiary, without the approval of the stockholders
of the Company. 
 7.3    Reports. Individual accounts shall be maintained for each Participant in the Plan.
Statements of Plan Accounts shall be given to Participants at least annually, which statements shall set forth the amounts of payroll deductions, the Option Price, the number of shares purchased and the remaining cash balance, if any. 

7.4    No Right to Employment. Nothing in the Plan shall be construed to give any person (including any
Participant) the right to remain in the employ of the Company, a Parent or a Subsidiary or to affect the right of the Company, any Parent or any Subsidiary to terminate the employment of any person (including any Participant) at any time, with or
without cause, which right is expressly reserved. 
 7.5    Amendment and Termination of the Plan. 

(a)    The Board may, in its sole discretion, amend, suspend or terminate the Plan at any time and from time to time;
provided, however, that without approval of the Company’s stockholders given within 12 months before or after action by the Board, the Plan may not be amended to increase the maximum number of shares of Common Stock subject to the
Plan or change the designation or class of Eligible Employees; and provided, further that without approval of the Company’s stockholders, the Plan may not be amended in any manner that would cause the Plan to no longer be an
“employee stock purchase plan” within the meaning of Section 423(b) of the Code. 
 (b)    In the event
the Administrator determines that the ongoing operation of the Plan may result in unfavorable financial accounting consequences, the Administrator may, to the extent permitted under Section 423 of the Code, in its discretion and, to the extent
necessary or desirable, modify or amend the Plan to reduce or eliminate such accounting consequence including, but not limited to: 

(i)    altering the Option Price for any Offering Period including an Offering Period underway at the
time of the change in Option Price; 

  
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 (ii)    shortening any Offering Period so that the Offering
Period ends on a new Exercise Date, including an Offering Period underway at the time of the Administrator action; and 

(iii)    allocating shares of Common Stock. 

Such modifications or amendments shall not require stockholder approval or the consent of any Participant. 

(c)    Upon termination of the Plan, the balance in each Participant’s Plan Account shall be refunded as soon as
practicable after such termination, without any interest thereon. 
 7.6    Use of Funds; No Interest Paid. All
funds received by the Company by reason of purchase of Common Stock under the Plan shall be included in the general funds of the Company free of any trust or other restriction and may be used for any corporate purpose. No interest shall be paid to
any Participant or credited under the Plan. 
 7.7    Term; Approval by Stockholders. No Option may be granted
during any period of suspension of the Plan or after termination of the Plan. The Plan shall be submitted for the approval of the Company’s stockholders within 12 months after the date of the Board’s initial adoption of the Plan. Options
may be granted prior to such stockholder approval; provided, however, that such Options shall not be exercisable prior to the time when the Plan is approved by the stockholders; provided, further that if such approval has
not been obtained by the end of the 12-month period, all Options previously granted under the Plan shall thereupon terminate and be canceled and become null and void without being exercised. 

7.8    Effect Upon Other Plans. The adoption of the Plan shall not affect any other compensation or incentive plans
in effect for the Company, any Parent or any Subsidiary. Nothing in the Plan shall be construed to limit the right of the Company, any Parent or any Subsidiary (a) to establish any other forms of incentives or compensation for Employees of the
Company or any Parent or any Subsidiary, or (b) to grant or assume Options otherwise than under the Plan in connection with any proper corporate purpose, including, but not by way of limitation, the grant or assumption of options in connection
with the acquisition, by purchase, lease, merger, consolidation or otherwise, of the business, stock or assets of any corporation, firm or association. 

7.9    Conformity to Securities Laws. Notwithstanding any other provision of the Plan, the Plan and the
participation in the Plan by any individual who is then subject to Section 16 of the Exchange Act shall be subject to any additional limitations set forth in any applicable exemption rule under Section 16 of the Exchange Act (including any
amendment to Rule 16b-3 of the Exchange Act) that are requirements for the application of such exemptive rule. To the extent permitted by applicable law, the Plan shall be deemed amended to the extent
necessary to conform to such applicable exemptive rule. 
 7.10    Notice of Disposition of Shares. Each
Participant shall give the Company prompt notice of any disposition or other transfer of any shares of Common Stock, acquired pursuant to the exercise of an Option, if such disposition or transfer is made (a) within two years after the
applicable Grant Date or (b) within one year after the transfer of such shares of Common Stock to such Participant upon exercise of such Option. The Company may direct that any certificates evidencing shares acquired pursuant to the Plan refer
to such requirement. 
 7.11    Tax Withholding. The Company or any Parent or any Subsidiary shall be entitled to
require payment in cash or deduction from other compensation payable to each Participant of any sums required by federal, state or local tax law to be withheld with respect to any purchase of shares of Common Stock under the Plan or any sale of such
shares. 

  
 11 

 7.12    Governing Law. The Plan and all rights and obligations
thereunder shall be construed and enforced in accordance with the laws of the State of Delaware, without regard to the conflict of law rules thereof or of any other jurisdiction. 

7.13    Notices. All notices or other communications by a participant to the Company under or in connection with
the Plan shall be deemed to have been duly given when received in the form specified by the Company at the location, or by the person, designated by the Company for the receipt thereof. 

7.14    Conditions To Issuance of Shares. 

(a)    Notwithstanding anything herein to the contrary, the Company shall not be required to issue or deliver any
certificates or make any book entries evidencing shares of Common Stock pursuant to the exercise of an Option by a Participant, unless and until the Board or the Committee has determined, with advice of counsel, that the issuance of such shares of
Common Stock is in compliance with all applicable laws, regulations of governmental authorities and, if applicable, the requirements of any securities exchange or automated quotation system on which the shares of Common Stock are listed or traded,
and the shares of Common Stock are covered by an effective registration statement or applicable exemption from registration. In addition to the terms and conditions provided herein, the Board or the Committee may require that a Participant make such
reasonable covenants, agreements, and representations as the Board or the Committee, in its discretion, deems advisable in order to comply with any such laws, regulations, or requirements. 

(b)    All certificates for shares of Common Stock delivered pursuant to the Plan and all shares of Common Stock issued
pursuant to book entry procedures are subject to any stop-transfer orders and other restrictions as the Committee deems necessary or advisable to comply with federal, state, or foreign securities or other laws, rules and regulations and the rules of
any securities exchange or automated quotation system on which the shares of Common Stock are listed, quoted, or traded. The Committee may place legends on any certificate or book entry evidencing shares of Common Stock to reference restrictions
applicable to the shares of Common Stock. 
 (c)    The Committee shall have the right to require any Participant to
comply with any timing or other restrictions with respect to the settlement, distribution or exercise of any Option, including a window-period limitation, as may be imposed in the sole discretion of the Committee. 

(d)    Notwithstanding any other provision of the Plan, unless otherwise determined by the Committee or required by any
applicable law, rule or regulation, the Company may, in lieu of delivering to any Participant certificates evidencing shares of Common Stock issued in connection with any Option, record the issuance of shares of Common Stock in the books of the
Company (or, as applicable, its transfer agent or stock plan administrator). 
 7.15    Equal Rights and
Privileges. Except with respect to sub-plans designed to be outside the scope of Section 423 of the Code, all Eligible Employees of the Company (or of any Designated Subsidiary) shall have equal
rights and privileges under this Plan to the extent required under Section 423 of the Code so that this Plan qualifies as an “employee stock purchase plan” within the meaning of Section 423 of the Code. Any provision of this Plan
that is inconsistent with Section 423 of the Code shall, without further act or amendment by the Company or the Board, be reformed to comply with the equal rights and privileges requirement of Section 423 of the Code. 

  
 12 

*    *    *    *    * 

I hereby certify that the foregoing Plan was adopted by the Board of Directors of Gritstone Oncology, Inc. on
                    , 2018. 
 I hereby certify
that the foregoing Plan was approved by the stockholders of Gritstone Oncology, Inc. on                     , 2018. 

Executed on                     , 2018. 

 

	
	   

	Corporate Secretary

  
 13EX-10.9

 Exhibit 10.9 

GRITSTONE ONCOLOGY, INC. 

EMPLOYMENT AGREEMENT 

This Employment Agreement (the “Agreement”), entered into as of September 16, 2018(the “Agreement
Date”), is between Gritstone Oncology, Inc., a Delaware corporation (the “Company”) and Andrew Allen (“Executive” and, together with the Company, the “Parties”).
This Agreement will become effective as a binding contract as of the Agreement Date, but the operative provisions of this Agreement will only become effective as of immediately prior to the time the Company’s registration statement relating to
the initial public offering of the Company’s common stock becomes effective (the “Effective Date”). This Agreement supersedes in its entirety that certain offer letter between Executive and the Company dated as of
October 7, 2015 (“Offer Letter”). 
 WHEREAS, the Company desires to assure itself of the
continued services of Executive by engaging Executive to perform services as an employee of the Company under the terms hereof; 

WHEREAS, Executive desires to provide continued services to the Company on the terms herein provided; and 

WHEREAS, the Parties desire to execute this Agreement to supersede the Offer Letter in its entirety and reflect certain changes to
Executive’s employment with the Company effective as of the Effective Date. 
 NOW, THEREFORE, in consideration of the
foregoing, and for other good and valuable consideration, including the respective covenants and agreements set forth below, the receipt and sufficiency of which are hereby acknowledged, the Parties hereto agree as follows: 

1. Employment. 
 (a)
General. The Company shall employ Executive upon the terms and conditions provided herein effective as of the Effective Date. 

(b) Position and Duties. Effective on the Effective Date, Executive: (i) shall continue to serve as the Company’s
President and Chief Executive Officer, with responsibilities, duties, and authority usual and customary for such position, subject to direction by the Company’s Board of Directors (the “Board”); (ii) shall continue to
report directly to the Board; and (iii) agrees promptly and faithfully to comply with all present and future policies, requirements, rules and regulations, and reasonable directions and requests, of the Company in connection with the
Company’s business. As of the Effective Date, Executive shall continue to serve as a member of the Board, and, while Executive is employed hereunder, the Company shall nominate Executive for reelection as a member of the Board at the end of
each Board term. At the Company’s request, Executive shall serve the Company and/or its subsidiaries and affiliates in such other capacities in addition to the foregoing as the Company shall designate, provided that such additional capacities
are consistent with Executive’s position as the Company’s President and Chief Executive Officer. In the event that Executive serves in any one or more of such additional capacities, Executive’s compensation shall not automatically be
increased on account of such additional service. 

  
 1 

 (c) Performance of Executive’s Duties. During Executive’s employment with
the Company, and except for periods of illness, vacation, disability, or reasonable leaves of absence or as discussed in Section 1(e), Executive shall devote Executive’s full time and attention to the business and affairs of the Company
pursuant to the general direction of the Board. The rights of Executive under this Agreement shall not be affected by any change in the title, duties, or capacity of Executive during Executive’s employment with the Company. 

(d) Principal Office. Executive will work principally at the Company’s facility located in Emeryville, California. 

(e) Exclusivity. Except with the prior written approval of the Board (which the Board may grant or withhold in its sole and
absolute discretion), Executive shall devote substantially all of Executive’s working time, attention, and energies to the business of the Company, except during any paid vacation or other excused absence periods. Nothing in this section
prevents Executive from engaging in additional activities in connection with personal investments and community affairs. Executive may also serve as a member of the board of directors or board of advisors of another organization provided
(i) such organization is not a competitor of the Company; (ii) Executive receives prior written approval from the Board; and (iii) such activities do not individually or in the aggregate interfere with the performance of
Executive’s duties under this Agreement, violate the Company’s standards of conduct then in effect, or raise a conflict under the Company’s conflict of interest policies. 

2. Term. The period of Executive’s employment under this Agreement shall commence on the Effective Date and shall continue
until Executive’s employment with the Company is terminated pursuant to Section 5. The phrase “Term” as used in this Agreement shall refer to the entire period of employment of Executive by the Company. 

3. Compensation and Related Matters. 

(a) Annual Base Salary. During the Term, Executive shall receive a base salary at the rate of $500,000 per year (as may be
increased from time to time, the “Annual Base Salary”), subject to withholdings and deductions, which shall be paid to Executive in accordance with the customary payroll practices and procedures of the Company. Such Annual
Base Salary shall be reviewed by the Board and/or the Compensation Committee of the Board, not less than annually. 
 (b) Annual
Bonus. Executive shall be eligible to receive a discretionary annual bonus based on Executive’s achievement of performance objectives as mutually agreed between Executive and the Board, such bonus to be targeted at 50% of Executive’s
Annual Base Salary (the “Annual Bonus”). Any Annual Bonus approved by the Board and/or the Compensation Committee of the Board shall be paid at the same time annual bonuses are paid to other executives of the Company
generally, subject to Executive’s continuous employment through the date of approval. 
 (c) Benefits. Executive shall be
entitled to participate in such employee and executive benefit plans and programs as the Company may from time to time offer to provide to its executives, subject to the terms and conditions of such plans. Notwithstanding the foregoing, nothing
herein is intended, or shall be construed, to require the Company to institute or continue any, or any particular, plan or benefit. 

  
 2 

 (d) Business Expenses. The Company shall reimburse Executive for all reasonable,
documented, out-of-pocket travel and other business expenses incurred by Executive in the performance of Executive’s duties to the Company in accordance with the
Company’s applicable expense reimbursement policies and procedures as are in effect from time to time. 
 (e) Vacation.
Executive will be entitled to paid vacation in accordance with the Company’s vacation policy. 
 4. Equity Awards.
Executive shall be eligible for such stock options and equity awards as may be determined by the Company, in its sole discretion. 

5. Termination.
 (a)
At-Will Employment. The Company and Executive acknowledge that Executive’s employment is and shall continue to be at-will, as defined under applicable law.
This means that it is not for any specified period of time and can be terminated by Executive or by the Company at any time, with or without advance notice, and for any or no particular reason or cause. It also means that Executive’s job
duties, title, and responsibility and reporting level, work schedule, compensation, and benefits, as well as the Company’s personnel policies and procedures, may be changed with prospective effect, with or without notice, at any time in the
sole discretion of the Company (subject to any ramification such changes may have under Section 6 of this Agreement). This “at-will” nature of Executive’s employment shall remain unchanged
during Executive’s tenure as an employee and may not be changed, except in an express writing signed by Executive and a duly-authorized officer of the Company. If Executive’s employment terminates for any lawful reason, Executive shall not
be entitled to any payments, benefits, damages, award, or compensation other than as provided in this Agreement. 
 (b) Notice of
Termination. During the Term, any termination of Executive’s employment by the Company or by Executive (other than by reason of death) shall be communicated by written notice (a “Notice of Termination”) from one
Party hereto to the other Party hereto (i) indicating the specific termination provision in this Agreement relied upon, if any, (ii) setting forth in reasonable detail the facts and circumstances claimed to provide a basis for termination
of Executive’s employment under the provision so indicated, and (iii) specifying the Date of Termination (as defined below). The failure by the Company to set forth in the Notice of Termination all of the facts and circumstances which
contribute to a showing of Cause (as defined below) shall not waive any right of the Company hereunder or preclude the Company from asserting such fact or circumstance in enforcing their rights hereunder. 

(c) Date of Termination. For purposes of this Agreement, “Date of Termination” shall mean the date of the
termination of Executive’s employment with the Company specified in a Notice of Termination. 
 (d) Deemed Resignation.
Upon termination of Executive’s employment for any reason, Executive shall be deemed to have resigned from all offices and board memberships, if any, then held with the Company or any of its affiliates, and, at the Company’s request,
Executive shall execute such documents as are necessary or desirable to effectuate such resignations. 

  
 3 

 6. Consequences of Termination. 

(a) Payments of Accrued Obligations upon all Terminations of Employment. Upon a termination of Executive’s employment for
any reason, Executive (or Executive’s estate or legal representative, as applicable) shall be entitled to receive, within 30 days after Executive’s Date of Termination (or such earlier date as may be required by applicable law): (i) any
portion of Executive’s Annual Base Salary earned through Executive’s Date of Termination not theretofore paid, (ii) any expenses owed to Executive under Section 3, (iii) any accrued but unused paid
time-off owed to Executive, (iv) any Annual Bonus approved by the Board and/or the Compensation Committee of the Board on or prior to the Date of Termination but unpaid as of the Date of Termination, and
(v) any amount arising from Executive’s participation in, or benefits under, any employee benefit plans, programs, or arrangements under Section 3, which amounts shall be payable in accordance with the terms and conditions of such
employee benefit plans, programs, or arrangements. Except as otherwise set forth in Sections 6(b) and (c), the payments and benefits described in this Section 6(a) shall be the only payments and benefits payable in the event of Executive’s
termination of employment for any reason. 
 (b) Severance Payments upon Covered Termination Outside a Change in Control
Period. If, during the Term, Executive experiences a Covered Termination outside a Change in Control Period (each as defined below), then in addition to the payments and benefits described in Section 6(a), the Company shall, subject to
Executive’s delivery to the Company of a waiver and release of claims agreement in a form approved by the Company (a “Release”) that becomes effective and irrevocable in accordance with Section 11(d), provide
Executive with the following: 
 (i) The Company shall pay to Executive an amount equal to the sum of
(i) Executive’s Annual Base Salary and (ii) Executive’s target Annual Bonus. Such amount will be subject to applicable withholdings and payable in a single lump sum cash payment on the first regular payroll date following the
date the Release becomes effective and irrevocable in accordance with Section 11(d). 
 (ii) During the period
commencing on the Date of Termination and ending on the 12-month anniversary thereof or, if earlier, the date on which Executive becomes eligible for comparable replacement coverage under a subsequent
employer’s group health plan (in any case, the “Non-CIC COBRA Period”), subject to Executive’s valid election to continue healthcare coverage under Section 4980B of the
Internal Revenue Code of 1986, as amended (the “Code”) and the regulations thereunder, the Company shall, in its sole discretion, either (A) continue to provide to Executive and Executive’s dependents, at the
Company’s sole expense, or (B) reimburse Executive and Executive’s dependents for coverage under its group health plan (if any) at the same levels in effect on the Date of Termination; provided, however, that if (1) any
plan pursuant to which such benefits are provided is not, or ceases prior to the expiration of the continuation coverage period to be, exempt from the application of Section 409A under Treasury Regulation
Section 1.409A-1(a)(5), (2) the Company is otherwise unable to continue to cover 

  
 4 

 
Executive or Executive’s dependents under its group health plans, or (3) the Company cannot provide the benefit without violating applicable law (including, without limitation,
Section 2716 of the Public Health Service Act), then, in any such case, an amount equal to each remaining Company subsidy shall thereafter be paid to Executive in substantially equal monthly installments over the
Non-CIC COBRA Period (or remaining portion thereof). 
 (c) Severance Payments upon Covered
Termination During a Change in Control Period. If, during the Term, Executive experiences a Covered Termination during a Change in Control Period, then, in addition to the payments and benefits described in Section 6(a), the Company shall,
subject to Executive’s delivery to the Company of a Release that becomes effective and irrevocable in accordance with Section 11(d), provide Executive with the following: 

(i) The Company shall pay to Executive an amount equal to the sum of (i) Executive’s Annual Base Salary
multiplied by 1.5 and (ii) Executive’s target Annual Bonus. Such amount will be subject to applicable withholdings and payable in a single lump sum cash payment on the first regular payroll date following the date the Release becomes
effective and irrevocable in accordance with Section 11(d). 
 (ii) During the period commencing on the Date of
Termination and ending on the 18-month anniversary thereof or, if earlier, the date on which Executive becomes eligible for comparable replacement coverage under a subsequent employer’s group health plan
(in any case, the “CIC COBRA Period”), subject to Executive’s valid election to continue healthcare coverage under Section 4980B of the Code and the regulations thereunder, the Company shall, in its sole discretion,
either (A) continue to provide to Executive and Executive’s dependents, at the Company’s sole expense, or (B) reimburse Executive and Executive’s dependents for coverage under its group health plan (if any) at the same
levels in effect on the Date of Termination; provided, however, that if (1) any plan pursuant to which such benefits are provided is not, or ceases prior to the expiration of the continuation coverage period to be, exempt from the
application of Section 409A under Treasury Regulation Section 1.409A-1(a)(5), (2) the Company is otherwise unable to continue to cover Executive or Executive’s dependents under its group health
plans, or (3) the Company cannot provide the benefit without violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), then, in any such case, an amount equal to each remaining Company subsidy
shall thereafter be paid to Executive in substantially equal monthly installments over the CIC COBRA Period (or remaining portion thereof). 

(iii) Cause any unvested equity awards, including any stock options, restricted stock awards and any such awards subject
to performance-based vesting, held by Executive as of the Date of Termination, to become fully vested and, if applicable, exercisable, and cause all restrictions and rights of repurchase on such awards to lapse with respect to all of the shares of
the Company’s Common Stock subject thereto. 
 (d) No Other Severance. The provisions of this Section 6 shall
supersede in their entirety any severance payment provisions in any severance plan, policy, program, or other arrangement maintained by the Company except as otherwise approved by the Board. 

  
 5 

 (e) No Requirement to Mitigate; Survival. Executive shall not be required to
mitigate the amount of any payment provided for under this Agreement by seeking other employment or in any other manner. Notwithstanding anything to the contrary in this Agreement, the termination of Executive’s employment shall not impair the
rights or obligations of any Party. 
 (f) Definition of Cause. For purposes hereof, “Cause” shall mean
any one of the following: (i) Executive’s material violation of any applicable material law or regulation respecting the business of the Company; (ii) Executive’s conviction of, or plea of nolo contendere to, a felony or
other crime involving moral turpitude; (iii) any act of dishonesty, fraud, or misrepresentation in relation to Executive’s duties to the Company which act is materially and demonstrably injurious to the Company; (iv) Executive’s
willful and repeated failure to perform in any material respect Executive’s duties hereunder after 15 days’ notice and an opportunity to cure such failure and a reasonable opportunity to present to the Board Executive’s position
regarding any dispute relating to the existence of such failure (other than on account of disability); (v) Executive’s failure to attempt in good faith to implement a clear and reasonable directive from the Board or to comply with any of the
Company’s policies and procedures which failure is either material or occurs after written notice from the Board; (vi) any act of gross misconduct which is materially and demonstrably injurious to the Company; or
(vii) Executive’s breach of fiduciary duty owed to the Company. 
 (g) Definition of Change in Control. For purposes
of this Agreement, “Change in Control” shall mean (i) the acquisition by any person or group of affiliated or associated persons of more than 50% of the outstanding capital stock of the Company or voting securities
representing more than 50% of the total voting power of outstanding securities of the Company; (ii) the consummation of a sale of all or substantially all of the assets of the Company to a third party; (iii) the consummation of any merger
involving the Company in which, immediately after giving effect to such merger, less than a majority of the total voting power of outstanding stock of the surviving or resulting entity is then “beneficially owned” (within the meaning of
Rule 13d-3 under the Securities Exchange Act of 1934, as amended) in the aggregate by the stockholders of the Company, as applicable, immediately prior to such merger. For the avoidance of doubt and
notwithstanding anything herein to the contrary, in no event shall a transaction constitute a “Change in Control” if: (w) its sole purpose is to change the state of the Company’s incorporation; (x) its sole purpose is to
create a holding company that will be owned in substantially the same proportions by the persons who held the Company’s securities immediately before such transaction; (y) it is effected primarily for the purpose of financing the Company
with cash (as determined by the Board without regard to whether such transaction is effectuated by a merger, equity financing, or otherwise); or (z) it constitutes, or includes sales of shares in connection with, the initial public offering of
the Company’s capital stock. Notwithstanding the foregoing, a “Change in Control” must also constitute a “change in control event,” as defined in Treasury Regulation
§1.409A-3(i)(5). 
 (h) Definition of Change in Control Period. For purposes
hereof, “Change in Control Period” shall mean the period of time commencing three months prior to a Change in Control and ending 12 months after such Change in Control. 

(i) Definition of Covered Termination. For purposes hereof, “Covered Termination” shall mean the
termination of Executive’s employment by the Company without Cause or by Executive for Good Reason, and shall not include a termination due to Executive’s death or disability. 

  
 6 

 (j) Definition of Good Reason. For purposes hereof, “Good
Reason” shall mean any one of the following: (i) the material reduction of Executive’s base salary or target annual performance bonus, (ii) the assignment to Executive of any duties materially and negatively inconsistent
in any respect of Executive’s position (including status, offices, titles and reporting requirements), authority, duties or responsibilities, or any other action by the Company which results in a material diminution in such position, authority,
duties or responsibilities (including without limitation a requirement to report to any person or entity other than the Board); or (iii) the Company’s material breach of this Agreement, provided, that, in each case, Executive will
not be deemed to have Good Reason unless (1) Executive first provides the Company with written notice of the condition giving rise to Good Reason within 30 days of its initial occurrence, (2) the Company or the successor company fails to
cure such condition within 30 days after receiving such written notice (the “Cure Period”), and (3) Executive’s resignation based on such Good Reason is effective within 30 days after the expiration of the Cure
Period. 
 7. Assignment and Successors. The Company shall assign its rights and obligations under this Agreement to any
successor to all or substantially all of the business or the assets of the Company (by merger or otherwise). This Agreement shall be binding upon and inure to the benefit of the Company, Executive, and their respective successors, assigns,
personnel, and legal representatives, executors, administrators, heirs, distributees, devisees, and legatees, as applicable. None of Executive’s rights or obligations may be assigned or transferred by Executive, other than Executive’s
rights to payments hereunder, which may be transferred only by will, operation of law, or as otherwise provided herein. 
 8.
Miscellaneous Provisions. 
 (a) Confidentiality Agreement. Executive hereby affirms Executive’s obligations under
that certain Proprietary Information and Inventions Assignment Agreement by and between Executive and the Company dated as of September 4, 2015 (the “Confidentiality Agreement”). The Confidentiality Agreement shall
survive the termination of this Agreement and Executive’s employment with the Company for the applicable period(s) set forth therein. Notwithstanding the foregoing, in the event of any conflict between the terms of the Confidentiality Agreement
and the terms of this Agreement, the terms of this Agreement shall prevail. 
 (b)
Non-Solicitation of Employees. For a period of one year following Executive’s Date of Termination, Executive shall not, either directly or indirectly (i) solicit for employment by any
individual, corporation, firm, or other business, any employees, consultants, independent contractors, or other service providers of the Company or any of its affiliates, or (ii) solicit any employee or consultant of the Company or any of its
affiliates to leave the employment or consulting of or cease providing services to the Company or any of its affiliates; provided, however, that the foregoing clauses (i) and (ii) shall not apply to a general advertisement or
solicitation (or any hiring pursuant to such advertisement or solicitation) that is not specifically targeted to such employees or consultants. 

  
 7 

 (c) Governing Law. This Agreement shall be governed, construed, interpreted, and
enforced in accordance with its express terms, and otherwise in accordance with the substantive laws of the State of California, without giving effect to any principles of conflicts of law, whether of the State of California or any other
jurisdiction, and where applicable, the laws of the United States, that would result in the application of the laws of any other jurisdiction. 

(d) Validity. The invalidity or unenforceability of any provision or provisions of this Agreement shall not affect the validity
or enforceability of any other provision of this Agreement, which shall remain in full force and effect. 
 (e) Counterparts.
This Agreement may be executed in several counterparts, each of which shall be deemed to be an original, but all of which together will constitute one and the same Agreement. Signatures delivered by facsimile shall be deemed effective for all
purposes. 
 (f) Entire Agreement. The terms of this Agreement, together with the Confidentiality Agreement, are intended by
the Parties to be the final expression of their agreement with respect to the employment of Executive by the Company and supersede all prior understandings and agreements, whether written or oral, regarding Executive’s service to the Company,
including without limitation, the Offer Letter. The Parties further intend that this Agreement, together with the Confidentiality Agreement, shall constitute the complete and exclusive statement of their terms and that no extrinsic evidence
whatsoever may be introduced in any judicial, administrative, or other legal proceeding to vary the terms of this Agreement or the Confidentiality Agreement. Notwithstanding the foregoing, in the event of any conflict between the terms of the
Confidentiality Agreement and the terms of this Agreement, the terms of this Agreement shall prevail. 
 (g) Amendments;
Waivers. This Agreement may not be modified, amended, or terminated except by an instrument in writing signed by Executive and a duly authorized representative of the Company. By an instrument in writing similarly executed, Executive or a duly
authorized officer of the Company, as applicable, may waive compliance by the other Party with any specifically identified provision of this Agreement that such other Party was or is obligated to comply with or perform; provided,
however, that such waiver shall not operate as a waiver of, or estoppel with respect to, any other or subsequent failure. No failure to exercise and no delay in exercising any right, remedy, or power hereunder shall preclude any other or
further exercise of any other right, remedy, or power provided herein or by law or in equity. 
 (h) Dispute Resolution. To
ensure the timely and economical resolution of disputes that arise in connection with this Agreement, Executive and the Company agree that any and all controversies, claims and disputes arising out of or relating to this Agreement, including without
limitation any alleged violation of its terms, shall be resolved be resolved solely and exclusively by final and binding arbitration held in Alameda County, California through JAMS in conformity with California law and the then-existing JAMS
employment arbitration rules, which can be found at https://www.jamsadr.com/rules-employment-arbitration/. The arbitrator shall: (a) provide adequate discovery for the resolution of the dispute; and (b) issue a written arbitration
decision, to include the arbitrator’s essential findings and conclusions and a statement of the award. The arbitrator shall award the prevailing Party attorneys’ fees and expert fees, if any. Notwithstanding the foregoing, it is
acknowledged that it will be impossible to measure in money 

  
 8 

 
the damages that would be suffered if the Parties fail to comply with any of the obligations imposed on them under Section 8(a), and that in the event of any such failure, an aggrieved
person will be irreparably damaged and will not have an adequate remedy at law. Any such person shall, therefore, be entitled to injunctive relief, including specific performance, to enforce such obligations, and if any action shall be brought in
equity to enforce any of the provisions of Section 8(a), none of the Parties shall raise the defense that there is an adequate remedy at law. Executive and the Company understand that by agreement to arbitrate any claim pursuant to this
Section 8(h), they will not have the right to have any claim decided by a jury or a court, but shall instead have any claim decided through arbitration. Executive and the Company waive any constitutional or other right to bring claims covered
by this Agreement other than in their individual capacities. Except as may be prohibited by applicable law, the foregoing waiver includes the ability to assert claims as a plaintiff or class member in any purported class or representative
proceeding. 
 (i) Enforcement. If any provision of this Agreement is held to be illegal, invalid, or unenforceable under
present or future laws, such provision shall be fully severable; this Agreement shall be construed and enforced as if such illegal, invalid, or unenforceable provision had never comprised a portion of this Agreement; and the remaining provisions of
this Agreement shall remain in full force and effect and shall not be affected by the illegal, invalid, or unenforceable provision or by its severance from this Agreement. Furthermore, in lieu of such illegal, invalid, or unenforceable provision
there shall be added automatically as part of this Agreement a provision as similar in terms to such illegal, invalid, or unenforceable provision as may be possible and be legal, valid, and enforceable. 

(j) Withholding. The Company shall be entitled to withhold from any amounts payable under this Agreement any federal, state,
local, or foreign withholding or other taxes or charges which the Company is required to withhold. The Company shall be entitled to rely on an opinion of counsel if any questions as to the amount or requirement of withholding shall arise. 

(k) Whistleblower Protections and Trade Secrets. Notwithstanding anything to the contrary contained herein, nothing in this
Agreement prohibits Executive from reporting possible violations of federal law or regulation to any United States governmental agency or entity in accordance with the provisions of and rules promulgated under Section 21F of the Securities
Exchange Act of 1934 or Section 806 of the Sarbanes-Oxley Act of 2002, or any other whistleblower protection provisions of state or federal law or regulation (including the right to receive an award for information provided to any such
government agencies). Furthermore, in accordance with 18 U.S.C. § 1833, notwithstanding anything to the contrary in this Agreement: (i) Executive shall not be in breach of this Agreement, and shall not be held criminally or civilly liable
under any federal or state trade secret law (x) for the disclosure of a trade secret that is made in confidence to a federal, state, or local government official or to an attorney solely for the purpose of reporting or investigating a suspected
violation of law, or (y) for the disclosure of a trade secret that is made in a complaint or other document filed in a lawsuit or other proceeding, if such filing is made under seal; and (ii) if Executive files a lawsuit for retaliation by
the Company for reporting a suspected violation of law, Executive may disclose the trade secret to Executive’s attorney, and may use the trade secret information in the court proceeding, if Executive files any document containing the trade
secret under seal, and does not disclose the trade secret, except pursuant to court order. 

  
 9 

 9. Prior Employment. Executive represents and warrants that Executive’s
acceptance of employment with the Company has not breached, and the performance of Executive’s duties hereunder will not breach, any duty owed by Executive to any prior employer or other person. Executive further represents and warrants to the
Company that (a) the performance of Executive’s obligations hereunder will not violate any agreement between Executive and any other person, firm, organization, or other entity; (b) Executive is not bound by the terms of any agreement
with any previous employer or other party to refrain from competing, directly or indirectly, with the business of such previous employer or other party that would be violated by Executive entering into this Agreement and/or providing services to the
Company pursuant to the terms of this Agreement; and (c) Executive’s performance of Executive’s duties under this Agreement will not require Executive to, and Executive shall not, rely on in the performance of Executive’s duties
or disclose to the Company or any other person or entity or induce the Company in any way to use or rely on any trade secret or other confidential or proprietary information or material belonging to any previous employer of Executive. 

10. Golden Parachute Excise Tax. 

(a) Best Pay. Any provision of this Agreement to the contrary notwithstanding, if any payment or benefit Executive would receive
from the Company pursuant to this Agreement or otherwise (“Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code and (ii) but for this sentence, be
subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then such Payment will be equal to the Reduced Amount (as defined below). The “Reduced Amount” will be either
(A) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax or (B) the entire Payment, whichever amount after taking into account all applicable federal, state,
and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate, net of the maximum reduction in federal income taxes which could be obtained from a deduction of such state and local taxes), results
in Executive’ s receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is
required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (A) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the
greatest economic benefit for Executive. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”). Notwithstanding the
foregoing, if the Reduction Method or the Pro Rata Reduction Method would result in any portion of the Payment being subject to taxes pursuant to Section 409A (as defined below) that would not otherwise be subject to taxes pursuant to
Section 409A, then the Reduction Method and/or the Pro Rata Reduction Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A as follows: (1) as a first priority, the modification
shall preserve to the greatest extent possible, the greatest economic benefit for Executive as determined on an after-tax basis; (2) as a second priority, Payments that are contingent on future events
(e.g., being terminated without cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and (3) as a third priority, Payments that are “deferred compensation” within the meaning of
Section 409A shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of Section 409A. 

  
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 (b) Accounting Firm. The accounting firm engaged by the Company for general tax
purposes as of the day prior to the Change in Control will perform the calculations set forth in Section 10(a). If the firm so engaged by the Company is serving as the accountant or auditor for the acquiring company, the Company will appoint a
nationally recognized accounting firm to make the determinations required hereunder. The Company will bear all expenses with respect to the determinations by such firm required to be made hereunder. The accounting firm engaged to make the
determinations hereunder will provide its calculations, together with detailed supporting documentation, to the Company within 30 days before the consummation of a Change in Control (if requested at that time by the Company) or such other time as
requested by the Company. If the accounting firm determines that no Excise Tax is payable with respect to a Payment, either before or after the application of the Reduced Amount, it will furnish the Company with documentation reasonably acceptable
to the Company that no Excise Tax will be imposed with respect to such Payment. Any good faith determinations of the accounting firm made hereunder will be final, binding and conclusive upon the Company and Executive. 

11. Section 409A. 

(a) General. The intent of the Parties is that the payments and benefits under this Agreement comply with or be exempt from
Section 409A of the Code and the Department of Treasury regulations and other interpretive guidance issued thereunder, including without limitation any such regulations or other guidance that may be issued after the Effective Date,
(“Section 409A”) and, accordingly, to the maximum extent permitted, this Agreement shall be interpreted to be in compliance therewith. If Executive notifies the Company that Executive has
received advice of tax counsel of a national reputation with expertise in Section 409A that any provision of this Agreement would cause Executive to incur any additional tax or interest under Section 409A (with specificity as to the reason
therefor) or the Company independently makes such determination, the Company and Executive shall take commercially reasonable efforts to reform such provision to try to comply with or be exempt from Section 409A through good faith modifications
to the minimum extent reasonably appropriate to conform with Section 409A, provided that any such modifications shall not increase the cost or liability to the Company. To the extent that any provision hereof is modified in order to
comply with or be exempt from Section 409A, such modification shall be made in good faith and shall, to the maximum extent reasonably possible, maintain the original intent and economic benefit to Executive and the Company of the applicable
provision without violating the provisions of Section 409A. 
 (b) Separation from Service. Notwithstanding any
provision to the contrary in this Agreement: (i) no amount that constitutes “deferred compensation” under Section 409A shall be payable pursuant to Section 6 unless the termination of Executive’s employment constitutes
a “separation from service” within the meaning of Section 1.409A-1(h) of the Department of Treasury Regulations (“Separation from Service”); (ii) for purposes of
Section 409A, Executive’s right to receive installment payments shall be treated as a right to receive a series of separate and distinct payments; and (iii) to the extent that any reimbursement of expenses or in-kind benefits constitutes “deferred compensation” under Section 409A, such reimbursement or benefit shall be provided no later than December
31st of the year following the year in which the expense was incurred. The amount of expenses reimbursed in one year shall not affect the amount eligible for reimbursement in any subsequent year.
The amount of any in-kind benefits provided in one year shall not affect the amount of in-kind benefits provided in any other year. 

  
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 (c) Specified Employee. Notwithstanding anything in this Agreement to the contrary,
if Executive is deemed by the Company at the time of Executive’s Separation from Service to be a “specified employee” for purposes of Section 409A, to the extent delayed commencement of any portion of the benefits to which
Executive is entitled under this Agreement is required in order to avoid a prohibited distribution under Section 409A, such portion of Executive’s benefits shall not be provided to Executive prior to the earlier of (i) the expiration
of the six-month period measured from the date of Executive’s Separation from Service with the Company or (ii) the date of Executive’s death. Upon the first business day following the expiration
of the applicable Section 409A period, all payments deferred pursuant to the preceding sentence shall be paid in a lump sum to Executive (or Executive’s estate or beneficiaries), and any remaining payments due to Executive under this
Agreement shall be paid as otherwise provided herein. 
 (d) Release. Notwithstanding anything to the contrary in this
Agreement, to the extent that any payments due under this Agreement as a result of Executive’s termination of employment are subject to Executive’s execution and delivery of a Release, (i) the Company shall deliver the Release to
Executive within ten business days following Executive’s Date of Termination, and the Company’s failure to deliver a Release prior to the expiration of such ten business day period shall constitute a waiver of any requirement to execute a
Release, (ii) if Executive fails to execute the Release on or prior to the Release Expiration Date (as defined below) or timely revokes Executive’s acceptance of the Release thereafter, Executive shall not be entitled to any payments or
benefits otherwise conditioned on the Release, and (iii) in any case where Executive’s Date of Termination and the Release Expiration Date fall in two separate taxable years, any payments required to be made to Executive that are
conditioned on the Release and are treated as nonqualified deferred compensation for purposes of Section 409A shall be made in the later taxable year. For purposes of this Section 11(d), “Release Expiration Date”
shall mean the date that is 21 days following the date upon which the Company timely delivers the Release to Executive, or, in the event that Executive’s termination of employment is “in connection with an exit incentive or other
employment termination program” (as such phrase is defined in the Age Discrimination in Employment Act of 1967), the date that is 45 days following such delivery date. To the extent that any payments of nonqualified deferred compensation
(within the meaning of Section 409A) due under this Agreement as a result of Executive’s termination of employment are delayed pursuant to this Section 11(d), such amounts shall be paid in a lump sum on the first payroll date
following the date that Executive executes and does not revoke the Release (and the applicable revocation period has expired) or, in the case of any payments subject to Section 11(d)(iii), on the first payroll period to occur in the subsequent
taxable year, if later. 
 12. Employee Acknowledgement. Executive acknowledges that Executive has read and understands this
Agreement, is fully aware of its legal effect, has not acted in reliance upon any representations or promises made by the Company other than those contained in writing herein, and has entered into this Agreement freely based on Executive’s own
judgment. 
 [Signature Page Follows] 

  
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 The Parties have executed this Agreement as of the Agreement Date. 

 

			
	GRITSTONE ONCOLOGY, INC.

 
			
		
	By:	 	 /s/ Jean-Marc Bellemin

			
	Name: Jean-Marc Bellemin
	Title:  Chief Financial Officer
	
	EXECUTIVE

 
			
		
	By:	 	 /s/ Andrew Allen

 
			
	Name: Andrew Allen
	
	Address:

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