GRTS Gritstone bio Inc

As filed with the Securities and Exchange Commission on March 11, 2021

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

2018 Incentive Award Plan

2018 Employee Stock Purchase Plan

(Full Title of the Plan)

Andrew Allen, M.D., Ph.D.

President and Chief Executive Officer

Gritstone Oncology, Inc.

5959 Horton Street, Suite 300

Emeryville, California 94608

(510) 871-6100

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Brian J. Cuneo, Esq.

Latham & Watkins LLP

140 Scott Drive

Menlo Park, California 94025

Telephone: (650) 328-4600

Facsimile: (650) 463-2600

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☒

REGISTRATION OF ADDITIONAL SECURITIES

By a registration statement on Form S-8 filed with the Securities and Exchange Commission (the “SEC”) on October 2, 2018 (File No. 333-227665) (the “Original Registration Statement”), Gritstone Oncology, Inc. (the “Registrant”) registered 2,782,920 shares of common stock, par value $0.0001 per share (the “Common Stock”), issuable under the Gritstone Oncology, Inc. 2018 Incentive Award Plan (the “2018 Plan”), and 282,334 shares of Common Stock issuable under the Gritstone Oncology, Inc. 2018 Employee Stock Purchase Plan (the “ESPP”). The Original Registration Statement also registered 2,355,270 shares of Common Stock issuable under the Gritstone Oncology, Inc. 2015 Equity Incentive Plan, as amended (the “2015 Plan”), which shares become available for issuance under the 2018 Plan to the extent awards under the 2015 Plan are forfeited or lapse unexercised and are not issued under the 2015 Plan. By a registration statement on Form S-8 filed with the SEC on March 28, 2019 (File No. 333- 230581) (the “2019 Registration Statement”), the Registrant registered an additional 1,160,000 shares of Common Stock issuable under the 2018 Plan and an additional 290,000 shares of Common Stock issuable under the ESPP. By a registration statement on Form S-8 filed with the SEC on March 11, 2020 (File No. 333-237095) (the “2020 Registration Statement”), the Registrant registered an additional 1,454,553 shares of Common Stock issuable under the 2018 Plan and an additional 363,638 shares of Common Stock issuable under the ESPP. The Registrant is hereby registering an additional 1,902,107 shares of Common Stock issuable under the 2018 Plan and an additional 475,526 shares of Common Stock issuable under the ESPP, which shares are now available for grant due to automatic annual increase provisions in the 2018 Plan and ESPP.

INCORPORATION BY REFERENCE OF CONTENTS OF

REGISTRATION STATEMENT ON FORM S-8

Pursuant to Instruction E of Form S-8, the contents of the Original Registration Statement, the 2019 Registration Statement and 2020 Registration Statement are incorporated by reference in this registration statement on Form S-8.

INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

The information called for in Part I of Form S-8 is not being filed with or included in this Form S-8 (by incorporation by reference or otherwise) in accordance with the rules and regulations of the SEC.