Statement of Changes in Beneficial Ownership (4)

FORM 4

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

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3235-0287

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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Rousseau Raphael	2. Issuer Name and Ticker or Trading Symbol Gritstone Oncology, Inc. [ GRTS ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    _____ 10% Owner __X__ Officer (give title below)    _____ Other (specify below) See Remarks
(Last)          (First)          (Middle) C/O GRITSTONE ONCOLOGY, INC., 5959 HORTON STREET, SUITE 300	3. Date of Earliest Transaction (MM/DD/YYYY) 3/8/2021
(Street) EMERYVILLE, CA 94608 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$13.87	3/8/2021		A		80000		4/8/2021 (1)	3/7/2031	Common Stock	80000	$0	80000	D

Explanation of Responses:

(1)

One forty-eighth (1/48th) of the shares initially subject to the option will vest on each monthly anniversary measured from March 8, 2021 (the "Vesting Commencement Date"), so that 100% of the shares subject to the option will be fully vested and exercisable as of the fourth anniversary of the Vesting Commencement Date, subject to the Reporting Person's continued service through each vesting date.

Remarks: Executive Vice President and Chief Medical Officer

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Rousseau Raphael C/O GRITSTONE ONCOLOGY, INC. 5959 HORTON STREET, SUITE 300 EMERYVILLE, CA 94608			See Remarks

Signatures
/s/ Rahsaan Thompson, Attorney-in-Fact for Raphael Rousseau		3/10/2021
**Signature of Reporting Person		Date