140 Scott Drive

Menlo Park, California 94025

Tel: +1.650.328.4600 Fax: +1.650.463.2600


   Beijing    Moscow
   Boston    Munich
   Brussels    New York
   Century City    Orange County
   Chicago    Paris
September 17, 2018    Dubai    Riyadh
   Düsseldorf    Rome
   Frankfurt    San Diego
   Hamburg    San Francisco
   Hong Kong    Seoul
   Houston    Shanghai
   London    Silicon Valley
   Los Angeles    Singapore
   Madrid    Tokyo
VIA EDGAR AND HAND DELIVERY    Milan    Washington, D.C.

United States Securities and Exchange Commission

Division of Corporation Finance

Office of Healthcare & Insurance

100 F Street, N.E.

Washington, D.C. 20549



Mary Beth Breslin


Ada D. Sarmento


Jim B. Rosenberg


Rolf Sundwall



Gritstone Oncology, Inc.


Registration Statement on Form S-1


Filed August 23, 2018


File No. 333-226976

Ladies and Gentlemen:

On behalf of our client, Gritstone Oncology, Inc. (the “Company”), we are hereby filing Amendment No. 1 to the Registration Statement on Form S-1 (“Amendment No. 1”). The Company previously filed its Registration Statement on Form S-1 with the U.S. Securities and Exchange Commission (the “Commission”) on August 23, 2018 (the “Registration Statement”). Amendment No. 1 has been revised to reflect the Company’s responses to the comment letter received September 14, 2018 from the staff of the Commission (the “Staff”). For your convenience, we are providing by overnight delivery a courtesy package that includes copies of Amendment No. 1, including copies which have been marked to show changes from the Registration Statement, as well as copy of this letter.

For ease of review, we have set forth below the numbered comment of your letter in bold type followed by the Company’s response thereto.

September 17, 2018

Page 2



Response dated September 6, 2018

Strategic Collaboration with bluebird bio, page 121



We note your response to our prior comment 1. Please revise the disclosure regarding this agreement on page 121 of your Registration Statement on Form S-1 to identify the royalty term.



Response:    The Company respectfully acknowledges the Staff’s comment and in response the Company has revised page 122 of the Registration Statement.

* * *

September 17, 2018

Page 3



We hope the foregoing answers are responsive to your comments. Please do not hesitate to contact me by telephone at (650) 463-3014 or by fax at (650) 463-2600 with any questions or comments regarding this correspondence.

Very truly yours,

/s/ Brian J. Cuneo

Brian J. Cuneo




Andrew Allen, M.D., Ph.D., Gritstone Oncology, Inc.


Jean Marc Bellemin, Gritstone Oncology, Inc.


Alan C. Mendelson, Latham & Watkins LLP


David Peinsipp, Cooley LLP