SRRA / Sierra Oncology Inc - Документы SEC, Годовой отчет, Доверенное заявление

SRRA / Sierra Oncology Inc / Rock Springs Capital Management LP Passive Investment

SC 13G/A 1 rocksprings-srra123122a3.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 3)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U404 (CUSIP Number) December 31, 2022 (Date of Event Which Requires Filing of this Statement) Check the appr

SRRA / Sierra Oncology Inc / Versor Investments LP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 15 CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE REPORTS UNDER SECTIONS 13

15-12G 1 d362390d1512g.htm 15-12G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 15 CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE REPORTS UNDER SECTIONS 13 AND 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. Commission File Number: 001-37490 SIERRA ONCOLOGY, INC. (Exact na

SRRA / Sierra Oncology Inc / Abingworth LLP Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 4) Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) John Heard Abingworth LLP Princes House 38 Jermyn Street London, England SW1Y 6DN +44 20 7534 1500 (Name, Address and T

SRRA / Sierra Oncology Inc / Vivo Capital IX, LLC - AMENDMENT NO. 4 TO SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 4)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U404 (CUSIP Number) July 1, 2022 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

Changes in Control of Registrant, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Termination of a Material Definitive Agreement, Material Modification to Rights of Security Holders, Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing, Financial Statements and Exhibits, Completion of Acquisition or Disposition of Assets

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 1, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission File

As filed with the Securities and Exchange Commission on July 1, 2022

S-8 POS 1 d314934ds8pos.htm S-8 POS As filed with the Securities and Exchange Commission on July 1, 2022 Registration No. 333-205693 Registration No. 333-209897 Registration No. 333-216392 Registration No. 333-223253 Registration No. 333-228263 Registration No. 333-229933 Registration No. 333-236854 Registration No. 333-241414 Registration No. 333-254126 Registration No. 333-263411 UNITED STATES S

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

Amended and Restated Bylaws of Sierra Oncology, Inc.

Exhibit 3.2 AMENDED AND RESTATED BY-LAWS OF SIERRA ONCOLOGY, INC. ARTICLE I OFFICES SECTION 1.1 REGISTERED OFFICE. The registered office shall be established and maintained at the office of Corporation Service Company, in the City of Wilmington, in the county of New Castle, in the State of Delaware, and said corporation shall be the registered agent of this corporation in charge thereof. SECTION 1

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

Amended and Restated Certificate of Incorporation of Sierra Oncology, Inc.

Exhibit 3.1 AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF SIERRA ONCOLOGY, INC. STATE OF DELAWARE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION A STOCK CORPORATION 1. The name of the corporation is Sierra Oncology, Inc. (the ?Corporation?). 2. The Registered Office of the Corporation in the State of Delaware is located at 251 Little Falls Drive in the City of Wilmington, County of New C

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

As filed with the Securities and Exchange Commission on July 1, 2022

S-8 POS 1 d314934ds8pos.htm S-8 POS As filed with the Securities and Exchange Commission on July 1, 2022 Registration No. 333-205693 Registration No. 333-209897 Registration No. 333-216392 Registration No. 333-223253 Registration No. 333-228263 Registration No. 333-229933 Registration No. 333-236854 Registration No. 333-241414 Registration No. 333-254126 Registration No. 333-263411 UNITED STATES S

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

As filed with the Securities and Exchange Commission on July 1, 2022

S-8 POS 1 d314934ds8pos.htm S-8 POS As filed with the Securities and Exchange Commission on July 1, 2022 Registration No. 333-205693 Registration No. 333-209897 Registration No. 333-216392 Registration No. 333-223253 Registration No. 333-228263 Registration No. 333-229933 Registration No. 333-236854 Registration No. 333-241414 Registration No. 333-254126 Registration No. 333-263411 UNITED STATES S

As filed with the Securities and Exchange Commission on July 1, 2022

As filed with the Securities and Exchange Commission on July 1, 2022 Registration No.

Other Events, Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 29, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fil

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 22, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fil

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 31, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission File

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Defi

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 6, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission File

Loan and Security Agreement dated January 21, 2022 by and between the Company and Oxford Finance LLC

EXHIBIT 10.4 LOAN AND SECURITY AGREEMENT THIS LOAN AND SECURITY AGREEMENT (as the same may from time to time be amended, modified, supplemented or restated, this ?Agreement?) dated as of January 21, 2022 (the ?Effective Date?) among OXFORD FINANCE LLC, a Delaware limited liability company with an office located at 115 South Union Street, Suite 300, Alexandria, VA 22314 (?Oxford?), as collateral ag

Sierra Oncology Reports First Quarter 2022 Results

Exhibit 99.1 Sierra Oncology Reports First Quarter 2022 Results SAN MATEO, CA, May 6, 2022- Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company with a mission to deliver targeted therapies that treat rare forms of cancer, today reported its financial and operating results for the first quarter ended March 31, 2022. ?By entering into a merger agreement with GSK, we are one step clo

SRRA / Sierra Oncology Inc / Longitude Capital Partners III, LLC - SC 13D/A Activist Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 4) SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) Patrick G. Enright Managing Member Longitude Capital Partners III, LLC 2740 Sand Hill Road, 2nd Floor Menlo Park, CA 94025 (650) 854-

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2022 OR ? Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncology, I

CALCULATION OF FILING FEE TABLES Schedule 14A (Form Type) Sierra Oncology, Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Transaction Valuation Proposed Maximum Aggregate Value of Transaction Fee rate Amount of Filing Fee Fees t

EX-FILING FEES 2 d571460dexfilingfees.htm EX-FILING FEES Exhibit 107 CALCULATION OF FILING FEE TABLES Schedule 14A (Form Type) Sierra Oncology, Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Transaction Valuation Proposed Maximum Aggregate Value of Transaction Fee rate Amount of Filing Fee Fees to be Paid $ 1,925,065,576.49 (1)(2) 0.0000927 $ 178,454 (3) Fees Previously Paid

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Defi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ☐ TRANSITION R

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Numbe

SRRA / Sierra Oncology Inc / Versor Investments LP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

Form of Support Agreement, dated as of April 12, 2022, by and among GlaxoSmithKline plc, Orikum Acquisition Inc., Sierra Oncology, Inc, and certain securityholders of Sierra Oncology, Inc.*

Exhibit 10.1 Execution Version SUPPORT AGREEMENT SUPPORT AGREEMENT, dated as of April 12, 2022 (this ?Agreement?), among GlaxoSmithKline plc, a public limited company organized under the laws of England and Wales (?Parent?), Orikum Acquisition Inc., a Delaware corporation and an indirect wholly owned Subsidiary of Parent (?Acquisition Sub?), Sierra Oncology, Inc. (the ?Company?) and the stockholde

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A (Rule 14A-101) PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A (Rule 14A-101) PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ? Definitive Proxy Statement ? Definitive Additional Materials ? Soliciting Material under ? 240.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A (Rule 14A-101) PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934

DFAN14A 1 d339351ddfan14a.htm DFAN14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 14A (Rule 14A-101) PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES EXCHANGE ACT OF 1934 Filed by the Registrant ☐ Filed by a Party other than the Registrant ☒ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as perm

Agreement and Plan of Merger, dated April 12, 2022, between GlaxoSmithKline plc, Orikum Acquisition Inc., and Sierra Oncology, Inc.*

Exhibit 2.1 Execution Version AGREEMENT AND PLAN OF MERGER between GLAXOSMITHKLINE PLC, ORIKUM ACQUISITION INC. and SIERRA ONCOLOGY, INC. Dated April 12, 2022 TABLE OF CONTENTS Page ARTICLE I DEFINITIONS & INTERPRETATIONS 2 1.1 Certain Definitions 2 1.2 Additional Definitions 16 1.3 Certain Interpretations 17 1.4 Company Disclosure Letter 20 ARTICLE II THE MERGER 21 2.1 The Merger 21 2.2 The Effec

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 12, 2022 SIERRA ONCOLOGY, INC.

Issued: 13 April 2022, London UK

Exhibit 99.1 PRESS RELEASE Issued: 13 April 2022, London UK GSK reaches agreement to acquire late-stage biopharmaceutical company Sierra Oncology for $1.9bn ? Sierra Oncology?s differentiated momelotinib has the potential to address the critical unmet medical needs of myelofibrosis patients with anaemia ? Momelotinib complements GSK?s existing expertise in haematology, with Sierra Oncology anticip

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 12, 2022 SIERRA ONCOLOGY, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 12, 2022 SIERRA ONCOLOGY, INC.

SRRA / Sierra Oncology Inc / Frazier Life Sciences Public Fund, L.P. - SC 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

Consulting Agreement dated March 22, 2022 between the Company and Mark Kowalski

Exhibit 10.2 CONSULTING AGREEMENT THIS CONSULTING AGREEMENT (this ?Agreement?) is made effective on the last signature date below (the ?Effective Date?), between Sierra Oncology, Inc., a Delaware corporation, having offices at 1820 Gateway Drive, Suite 110 San Mateo, CA 94404 U.S.A. the ?Company?), and Mark Kowalski, MD, PhD, an individual, whose address is 10 Priscilla Lane, Winchester, MA, Unite

Transition Agreement and Release dated March 22, 2022 between the Company and Mark Kowalski

Exhibit 10.1 TRANSITION AGREEMENT AND RELEASE This Transition Agreement and Release (?Agreement?) is made by and between Mark Kowalski (?Employee?) and Sierra Oncology, Inc. (the ?Company?) (collectively referred to as the ?Parties? or individually referred to as a ?Party?). RECITALS WHEREAS, Employee is employed by the Company; WHEREAS, Employee signed an Employment Agreement with the Company dat

Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 22, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fi

SRRA / Sierra Oncology Inc / Abingworth LLP - SIERRA ONCOLOGY 13D AMENDMENT NO. 3 Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3) Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) John Heard Abingworth LLP Princes House 38 Jermyn Street London, England SW1Y 6DN +44 20 7534 1500 (Name, Address and T

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13D, dated March 10, 2022, with respect to the ordinary shares of Sierra Oncology, Inc.

SRRA / Sierra Oncology Inc / ORBIMED ADVISORS LLC - AMENDMENT NO. 3 Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3)* Sierra Oncology, Inc. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 82640U 10 7 (CUSIP Number) OrbiMed Advisors LLC OrbiMed Capital GP VII LLC OrbiMed Genesis GP LLC OrbiMed Capital LLC 601 Lexington Avenue, 54th Floor New York, NY 10022 T

As filed with the Securities and Exchange Commission on March 10, 2022

As filed with the Securities and Exchange Commission on March 10, 2022 Registration No.

Description of Securities

EXHIBIT 4.4 DESCRIPTION OF CAPITAL STOCK General Our authorized capital stock consists of 500,000,000 shares of common stock, $0.001 par value per share, and 10,000,000 shares of undesignated preferred stock, $0.001 par value per share. The following description summarizes the most important terms of our capital stock. Because it is only a summary, it does not contain all the information that may

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number: 001-37490 Sierra Oncology, Inc. (Ex

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) Sierra Oncology, Inc.

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 10, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fi

Sierra Oncology Reports 2021 Year End Results – Planned Q2 2022 NDA submission following positive topline data from MOMENTUM clinical trial of momelotinib in symptomatic and anemic myelofibrosis patients – – Financial position significantly strengthe

Exhibit 99.1 Sierra Oncology Reports 2021 Year End Results ? Planned Q2 2022 NDA submission following positive topline data from MOMENTUM clinical trial of momelotinib in symptomatic and anemic myelofibrosis patients ? ? Financial position significantly strengthened ? SAN MATEO, CA, March 10, 2022 - Sierra Oncology, Inc. (NASDAQ: SRRA), a late-stage biopharmaceutical company dedicated to deliverin

2018 Equity Inducement Plan, as amended, and forms of award agreements thereunder.

EXHIBIT 10.5 SIERRA ONCOLOGY, INC. 2018 EQUITY INDUCEMENT PLAN ADOPTED BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: SEPTEMBER 2018 FIRST AMENDMENT BY THE BOARD OF DIRECTORS: JUNE 2020 SECOND AMENDMENT BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: FEBRUARY 2021 THIRD AMENDMENT BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: FEBRUARY 2022 1.PURPOSE. The purpose of thi

Current Report

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 6, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fil

SRRA / Sierra Oncology Inc / Rock Springs Capital Management LP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.

SRRA / Sierra Oncology Inc / CAXTON CORP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

SRRA / Sierra Oncology Inc / Venrock Healthcare Capital Partners II, L.P. - SC 13G/A Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U107 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the

SRRA / Sierra Oncology Inc / New Leaf Biopharma Opportunities I, L.P. - SC 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2 (Amendment No. 3) Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) December 31, 2021 (Date of Event Whi

SRRA / Sierra Oncology Inc / Vivo Capital IX, LLC - AMENDMENT NO. 3 TO SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 3)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U404 (CUSIP Number) January 31, 2022 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursu

SRRA / Sierra Oncology Inc / GILEAD SCIENCES INC Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO ? 240.13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO ? 240.13d-2. (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) December 31, 2021

SRRA / Sierra Oncology Inc / Abingworth LLP - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2) Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) John Heard Abingworth LLP Princes House 38 Jermyn Street London, England SW1Y 6DN +44 20 7534 1500 (Name, Address and T

SRRA / Sierra Oncology Inc / ADAGE CAPITAL PARTNERS GP, L.L.C. Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant

SRRA / Sierra Oncology Inc / PFM Health Sciences, LP - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Rule 13d-102) Information Statement Pursuant to Rules 13d-1 and 13d-2 Under the Securities Exchange Act of 1934 (Amendment No. )* Sierra Oncology, Inc. (Name of Issuer) Common stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) January 27, 2022 Date of Event Which Requires Fi

JOINT FILING AGREEMENT

EXHIBIT 99.1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13G filed herewith (and any amendments thereto), relating to the common stock of Sierra Oncology, Inc., a California corporation, is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(c) under the Securities Exchange Act of 1934, as amended, on behalf of each of the u

SRRA / Sierra Oncology Inc / Longitude Capital Partners III, LLC - SC 13D/A Activist Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3) SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) Patrick G. Enright Managing Member Longitude Capital Partners III, LLC 2740 Sand Hill Road, 2nd Floor Menlo Park, CA 94025 (650) 854-

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned, and any amendments thereto executed by the undersigned shall be filed on behalf of each of the undersigned without the necessity of filing any additional joint filing agreement.

SRRA / Sierra Oncology Inc / ORBIMED ADVISORS LLC - AMENDMENT NO. 2 Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2)* Sierra Oncology, Inc. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 82640U 10 7 (CUSIP Number) OrbiMed Advisors LLC OrbiMed Capital GP VII LLC OrbiMed Genesis GP LLC OrbiMed Capital LLC 601 Lexington Avenue, 54th Floor New York, NY 10022 T

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13D, dated February 2, 2022, with respect to the ordinary shares of Sierra Oncology, Inc.

Form of Lock-up Agreement January 24, 2022

Exhibit 3 Form of Lock-up Agreement January 24, 2022 Jefferies LLC Cantor Fitzgerald & Co.

SRRA / Sierra Oncology Inc / Frazier Life Sciences VIII, L.P. - SC 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No.

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 26, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Form of Prefunded Warrant

Exhibit 4.1 FORM OF PRE-FUNDED WARRANT TO PURCHASE COMMON STOCK Number of Shares: [ ] (subject to adjustment) Warrant No. Original Issue Date: January, 31, 2022 Sierra Oncology, Inc. , a Delaware corporation (the ?Company?), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [ ] or its registered assigns (the ?Holder?), is enti

4,074,075 Shares of Common Stock Pre-Funded Warrants to Purchase 925,925 Shares of Common Stock

Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-260799 PROSPECTUS SUPPLEMENT (To Prospectus dated November 12, 2021) 4,074,075 Shares of Common Stock Pre-Funded Warrants to Purchase 925,925 Shares of Common Stock We are offering an aggregate of 4,074,075 shares of our common stock, $0.001 par value per share. We are also offering to an investor the opportunity to purchase,

Underwriting Agreement, dated as of January 26, 2022

EX-1.1 2 d286358dex11.htm EX-1.1 Exhibit 1.1 4,074,075 Shares of Common Stock And Pre-Funded Warrants to Purchase 925,925 Shares of Common Stock Sierra Oncology, Inc. UNDERWRITING AGREEMENT January 26, 2022 JEFFERIES LLC CANTOR FITZGERALD & CO. As Representatives of the several Underwriters c/o JEFFERIES LLC 520 Madison Avenue New York, New York 10022 c/o CANTOR FITZGERALD & CO. 499 Park Avenue Ne

4,074,075 Shares of Common Stock Pre-Funded Warrants to Purchase 925,925 Shares of Common Stock

Issuer Free Writing Prospectus Filed Pursuant to Rule 433 Dated January 26, 2022 Relating to Preliminary Prospectus Supplement Dated January 25, 2022 Registration Statement No.

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant, Results of Operations and Financial Condition, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 21, 2022 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

$100,000,000 Common Stock

Table of Contents Filed Pursuant to Rule 424(b)5 Registration No. 333-260799 The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission and is effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell th

Sierra Oncology Announces Momelotinib Achieved Statistically Significant Benefit on Symptoms, Anemia and Splenic Size in the Pivotal MOMENTUM Study for Myelofibrosis —New Drug Application submission planned for second quarter of 2022— —Full data set

Exhibit 99.1 Sierra Oncology Announces Momelotinib Achieved Statistically Significant Benefit on Symptoms, Anemia and Splenic Size in the Pivotal MOMENTUM Study for Myelofibrosis ?New Drug Application submission planned for second quarter of 2022? ?Full data set to be presented at an upcoming medical meeting? SAN MATEO, Calif., January 25, 2022?Sierra Oncology, Inc. (NASDAQ: SRRA), a late-stage bi

Sierra Oncology Provides Financial Update to Support the Future Commercialization of Momelotinib —Oxford Finance Debt Facility for up to $125 Million— —Series B Warrants Will Expire in 75 Days, and if Fully Exercised, Could Provide An Additional $33.

Exhibit 99.2 Sierra Oncology Provides Financial Update to Support the Future Commercialization of Momelotinib ?Oxford Finance Debt Facility for up to $125 Million? ?Series B Warrants Will Expire in 75 Days, and if Fully Exercised, Could Provide An Additional $33.3 Million? SAN MATEO, CA, January 25, 2022?Sierra Oncology, Inc. (NASDAQ: SRRA), a late-stage biopharmaceutical company dedicated to deli

SIERRA ONCOLOGY, INC. 1820 Gateway Drive, Suite 110 San Mateo, California 94404 November 10, 2021

SIERRA ONCOLOGY, INC. 1820 Gateway Drive, Suite 110 San Mateo, California 94404 November 10, 2021 Via EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, DC 20549 Attention: Office of Life Sciences Re: Sierra Oncology, Inc. Registration Statement on Form S-3 Filed November 5, 2021 File No. 333-260799 Requested Date: November 12, 202

SRRA / Sierra Oncology Inc / Longitude Capital Partners III, LLC - SC 13D/A Activist Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2) SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) Patrick G. Enright Managing Member Longitude Capital Partners III, LLC 2740 Sand Hill Road, 2nd Floor Menlo Park, CA 94025 (650) 854-

SRRA / Sierra Oncology Inc / Vivo Capital IX, LLC - AMENDMENT NO. 2 TO SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2 )* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U404 (CUSIP Number) November 5, 2021 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule purs

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2021 OR ? Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncolog

Registration No. 333-260799

Table of Contents As filed with the Securities and Exchange Commission on November 5, 2021 Registration No.

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13D, dated November 5, 2021, with respect to the ordinary shares of Sierra Oncology, Inc.

Form of Indenture

Exhibit 4.6 SIERRA ONCOLOGY, INC. INDENTURE Dated as of , 20 [] Trustee TABLE OF CONTENTS Page ARTICLE I DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.1 Definitions 1 Section 1.2 Other Definitions 4 Section 1.3 Incorporation by Reference of Trust Indenture Act 5 Section 1.4 Rules of Construction 5 ARTICLE II THE SECURITIES 5 Section 2.1 Issuable in Series 5 Section 2.2 Establishment of Te

SRRA / Sierra Oncology Inc / ORBIMED ADVISORS LLC - AMENDMENT NO. 1 Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 82640U 10 7 (CUSIP Number) OrbiMed Advisors LLC OrbiMed Capital GP VII LLC OrbiMed Genesis GP LLC OrbiMed Capital LLC 601 Lexington Avenue, 54th Floor New York, NY 10022 T

License Agreement dated August 3, 2021 by and between the Registrant and AstraZeneca AB.

Confidential EXHIBIT 10.1 [***] = redacted LICENSE AGREEMENT between AstraZeneca AB and Sierra Oncology, Inc., Dated as of August 03, 2021 Confidential TABLE OF CONTENTS RECITALS 1 ARTICLE 1 DEFINITIONS 1 ARTICLE 2 GRANT OF RIGHTS 14 ARTICLE 3 DEVELOPMENT, REGULATORY, TRANSITION AND COMMERCIALIZATION ACTIVITIES 16 ARTICLE 4 PAYMENTS AND TAXES 21 ARTICLE 5 INTELLECTUAL PROPERTY 28 ARTICLE 6 CONFIDE

Financial Statements and Exhibits, Results of Operations and Financial Condition, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 5, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Sierra Oncology Reports Third Quarter 2021 Results – MOMENTUM study on track for topline data read-out by February 2022 – – Global in-licensing deal expands myelofibrosis pipeline and provides options for combination studies in other hematologic mali

Exhibit 99.1 Sierra Oncology Reports Third Quarter 2021 Results ? MOMENTUM study on track for topline data read-out by February 2022 ? ? Global in-licensing deal expands myelofibrosis pipeline and provides options for combination studies in other hematologic malignancies and solid tumors ? SAN MATEO, CA, November 5, 2021- Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company with a

SRRA / Sierra Oncology Inc / Abingworth LLP - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1) Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) John Heard Abingworth LLP Princes House 38 Jermyn Street London, England SW1Y 6DN +44 20 7534 1500 (Name, Address and T

Up to $50,000,000 Common Stock

Table of Contents As Filed Pursuant to Rule 424(b)5 Registration No. 333-241443 PROSPECTUS SUPPLEMENT (To prospectus dated August 13, 2020) Up to $50,000,000 Common Stock We have previously entered into an Open Market Sale AgreementSM, or the sales agreement, with Jefferies LLC, or Jefferies, relating to shares of our common stock offered by this prospectus supplement. In accordance with the terms

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 8, 2021 SIERRA ONCOLOGY

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 8, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Form of Amendment No. 1 to the Series A Warrant to Purchase Common Stock

Exhibit 4.1 AMENDMENT NO. 1 TO THE SERIES A WARRANT TO PURCHASE COMMON STOCK This Amendment No. 1 to the Series A Warrant to Purchase Common Stock dated September 8, 2021 is made effective as of September 8, 2021 (the ?Amendment?), by and among Sierra Oncology, Inc., a Delaware corporation (the ?Company?), and [ ] (the ?Investor? and together with the Company, the ?Parties?). WHEREAS, the Company

Form of Amendment No. 1 to the Series B Warrant to Purchase Common Stock

Exhibit 4.2 AMENDMENT NO. 1 TO THE SERIES B WARRANT TO PURCHASE COMMON STOCK This Amendment No. 1 to the Series B Warrant to Purchase Common Stock dated September 8, 2021 is made effective as of September 8, 2021 (the ?Amendment?), by and among Sierra Oncology, Inc., a Delaware corporation (the ?Company?), and [ ] (the ?Investor? and together with the Company, the ?Parties?). WHEREAS, the Company

POWER OF ATTORNEY

EXHIBIT B POWER OF ATTORNEY KNOW ALL BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Steve R.

SRRA / Sierra Oncology Inc / Frazier Life Sciences Public Fund, L.P. - SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

AGREEMENT

EXHIBIT A AGREEMENT Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of Common Stock of Sierra Oncology, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2021 OR ? Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncology, In

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 5, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission F

Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 3, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission F

Sierra Oncology Reports Second Quarter 2021 Results – Enrollment Complete for Pivotal MOMENTUM Phase 3 Trial in Myelofibrosis – – Topline Data Expected in Q1 2022; NDA Filing to Follow in Mid-2022 –

Exhibit 99.1 Sierra Oncology Reports Second Quarter 2021 Results ? Enrollment Complete for Pivotal MOMENTUM Phase 3 Trial in Myelofibrosis ? ? Topline Data Expected in Q1 2022; NDA Filing to Follow in Mid-2022 ? SAN MATEO, CA, August 5, 2021- Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company with a mission to deliver targeted therapies that treat rare forms of cancer, today repo

Sierra Oncology Signs Exclusive Global In-Licensing Agreement with AstraZeneca for Novel BET Inhibitor to Expand Myelofibrosis Pipeline —Combination study to build upon momelotinib’s differentiated potential as a cornerstone myelofibrosis therapy-—

Exhibit 99.1 Sierra Oncology Signs Exclusive Global In-Licensing Agreement with AstraZeneca for Novel BET Inhibitor to Expand Myelofibrosis Pipeline ?Combination study to build upon momelotinib?s differentiated potential as a cornerstone myelofibrosis therapy-? SAN MATEO, CA, August 5, 2021 - Sierra Oncology, Inc. (NASDAQ: SRRA), a late-stage biopharmaceutical company on a mission to deliver targe

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 8, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission Fil

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Ru

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 1, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) N/A (Former name or former address, if changed since last report) Delaware 001-37490 20-01389

Sierra Oncology Welcomes Two New Independent Directors to its Board —Georgia Erbez and Christy Oliger bring additional strategy, finance and commercial experience as Sierra prepares for commercialization of momelotinib—

Exhibit 99.1 For Distribution Thursday, June 3 at 7:00 am ET Sierra Oncology Welcomes Two New Independent Directors to its Board ?Georgia Erbez and Christy Oliger bring additional strategy, finance and commercial experience as Sierra prepares for commercialization of momelotinib? SAN MATEO, June 3, 2021?Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company on a quest to deliver targ

Financial Statements and Exhibits, Results of Operations and Financial Condition, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 7, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission File

Quarterly Report - 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2021 OR ? Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncology, I

Up to $50,000,000 Common Stock

Table of Contents As Filed Pursuant to Rule 424(b)5 Registration No. 333-241443 PROSPECTUS SUPPLEMENT (To prospectus dated August 13, 2020) Up to $50,000,000 Common Stock We have previously entered into an Open Market Sale Agreement, or the sales agreement, with Jefferies LLC, or Jefferies, relating to shares of our common stock offered by this prospectus supplement. In accordance with the terms o

Sierra Oncology Reports First Quarter 2021 Results – Pivotal MOMENTUM Phase 3 Trial Anticipated to Complete Enrollment in June 2021 – – Topline Data Now Expected in Q1 2022 –

Exhibit 99.1 Sierra Oncology Reports First Quarter 2021 Results ? Pivotal MOMENTUM Phase 3 Trial Anticipated to Complete Enrollment in June 2021 ? ? Topline Data Now Expected in Q1 2022 ? SAN MATEO, CA, May 7, 2021 - Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company on a quest to deliver targeted therapies that treat rare forms of cancer, today reported its financial and operati

Schedule 14A

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (

- DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Ru

Sierra Oncology, Inc.

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) March 22, 2021 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant to wh

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 11, 2021 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission F

Annual Report - 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2020 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number: 001-37490 Sierra Oncology, Inc. (Ex

Office Sublease, dated December 1, 2020, by and between Sierra Oncology Canada ULC and Scougall Management (1987) Limited and consented to on December 18, 2020 by Van885 West Georgia GP Ltd. and Ontrea Inc., the general partners of Van885 West Georgia LP.

EXHIBIT 10.14 SUBLANDLORD: SIERRA ONCOLOGY CANADA ULC SUBTENANT: SCOUGALL MANAGEMENT (1987) LIMITED BUILDING: Suite 2150 885 WEST GEORGIA STREET VANCOUVER, BC S U B L E A S E S U B L E A S E This Sublease (the ?Sublease?) date as of the 1st day of December 2020 BETWEEN SIERRA ONCOLOGY CANADA ULC (The ?Sublandlord?); and SCOUGALL MANAGEMENT (1987) LIMITED (The ?Subtenant?) Sublandlord subleases to

2015 Equity Incentive Plan, as amended, and forms of award agreements thereunder.

Exhibit 10.3 SIERRA ONCOLOGY, INC. 2015 EQUITY INCENTIVE PLAN As amended on January 21, 2020 1. PURPOSE. The purpose of this Plan is to provide incentives to attract, retain and motivate eligible persons whose present and potential contributions are important to the success of the Company, and any Parents and Subsidiaries that exist now or in the future, by offering them an opportunity to particip

2018 Equity Inducement Plan, as amended

EXHIBIT 10.5 SIERRA ONCOLOGY, INC. 2018 EQUITY INDUCEMENT PLAN ADOPTED BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: SEPTEMBER 2018 FIRST AMENDMENT BY THE BOARD OF DIRECTORS: JUNE 2020 SECOND AMENDMENT BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: FEBRUARY 2021 1.PURPOSE. The purpose of this Plan is to provide incentives to attract, retain and motivate eligible persons whose

Registration Statement No. 333-254126, filed with the Commission on March 11, 2021, relating to the registration of (i) 445,139 additional Shares under the 2015 Equity Incentive Plan and (ii) 500,000 additional Shares under the 2018 Equity Inducement Plan;

As filed with the Securities and Exchange Commission on March 11, 2021 Registration No.

Sierra Oncology Reports 2020 Year End Results – MOMENTUM Phase 3 Trial on Track to Complete Enrollment in mid-2021 with Top-line Data Anticipated in H1 2022 – – Data Presented Throughout the Year Included Long-Term Overall Survival, Efficacy in Vario

Exhibit 99.1 Sierra Oncology Reports 2020 Year End Results – MOMENTUM Phase 3 Trial on Track to Complete Enrollment in mid-2021 with Top-line Data Anticipated in H1 2022 – – Data Presented Throughout the Year Included Long-Term Overall Survival, Efficacy in Various Patient Subsets and Dosing Durability – – Key Appointments Made to Executive Team in Preparation for Commercial Execution – SAN MATEO,

Amendment No. 1 to the License Agreement dated November 10, 2020 by and between the Registrant and CRT Pioneer Fund LP.

EXHIBIT 10.12 CERTAIN IDENTIFIED INFORMATION HAS BEEN OMITTED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND WOULD LIKELY CAUSE COMPETITIVE HARM TO THE REGISTRANT IF PUBLICLY DISCLOSED. [*****] INDICATES THAT INFORMATION HAS BEEN OMITTED. Amendment No.1 to the License Agreement This Amendment of the License Agreement (?Amendment No. 1?) is made and entered on the last signature date below by and

Office Lease, dated December 10, 2020 and effective December 14, 2020, by and between Sierra Oncology, Inc. and KW Fund VI-San Mateo, LLC.

EXHIBIT 10.15 OFFICE LEASE SAN MATEO GATEWAY 1820 GATEWAY DRIVE, SAN MATEO, CA 94404 KW FUND VI-SAN MATEO, LLC, a Delaware limited liability company, as Landlord, and SIERRA ONCOLOGY, INC., a Delaware corporation, as Tenant SAN MATEO GATEWAY SUMMARY OF BASIC LEASE INFORMATION This Summary of Basic Lease Information (the "Summary") is hereby incorporated by reference into and made a part of the att

Subsidiaries of the Registrant.

EX-21.1 7 srra-ex21111.htm EX-21.1 EXHIBIT 21.1 LIST OF SUBSIDIARIES OF SIERRA ONCOLOGY, INC. Subsidiary Jurisdiction of Incorporation or Organization Sierra Oncology Canada ULC Canada, British Columbia

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Secur

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U107 (CUSIP Number) January 26, 2021 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the ru

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)*

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Secur

SC 13G/A 1 brhc1009804sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U107 (CUSIP Number) December 31, 2020 (Date of Event which Requires Filing of this Statement) Ch

Financial Statements and Exhibits, Other Events

8-K 1 d65889d8k.htm 8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 12, 2021 SIERRA ONCOLOGY, INC. (Exact Name of Registrant as Specified in Charter) Delaware 001-37490 20-0138994 (State or Other Jurisdiction of Incorpor

Up to $30,000,000 Common Stock

424B5 Table of Contents As Filed Pursuant to Rule 424(b)5 Registration No. 333-241443 PROSPECTUS SUPPLEMENT (To prospectus dated August 13, 2020) Up to $30,000,000 Common Stock We have previously entered into an Open Market Sale AgreementSM, or the sales agreement, with Jefferies LLC, or Jefferies, relating to shares of our common stock offered by this prospectus supplement. In accordance with the

Entry into a Material Definitive Agreement - 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 18, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissio

Entry into a Material Definitive Agreement, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant - 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 14, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissio

- 8-K NOVEMBER 9 2020

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 9, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Quarterly Report - 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2020 OR ☐ Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncolog

Financial Statements and Exhibits, Results of Operations and Financial Condition - 8-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 5, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Sierra Oncology Reports Third Quarter 2020 Results - MOMENTUM Phase 3 clinical trial enrollment on track; top-line data anticipated in H1 2022 -

Exhibit 99.1 Sierra Oncology Reports Third Quarter 2020 Results - MOMENTUM Phase 3 clinical trial enrollment on track; top-line data anticipated in H1 2022 - VANCOUVER, November 5, 2020 - Sierra Oncology, Inc. (SRRA), a late-stage biopharmaceutical company focused on the Phase 3 execution, registration and potential commercialization of momelotinib, a novel drug that may address serious unmet need

SRRA / Sierra Oncology / Rock Springs Capital Management LP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

-

CORRESP SIERRA ONCOLOGY, INC. 2150 – 885 West Georgia Street Vancouver, British Columbia, Canada V6C 3E8 August 11, 2020 United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, DC 20549 Attention: Office of Life Sciences Re: Sierra Oncology, Inc. Registration Statement on Form S-3 Filed August 6, 2020 File No. 333-241443 Requested Date: Augus

Open Market Sale AgreementSM dated August 6, 2020, by and between the Registrant and Jefferies LLC

EX-1.2 Exhibit 1.2 OPEN MARKET SALE AGREEMENTSM August 6, 2020 JEFFERIES LLC 520 Madison Avenue New York, New York 10022 Ladies and Gentlemen: Sierra Oncology, Inc., f/k/a ProNAi Therapeutics, Inc., a Delaware corporation (the “Company”), proposes, subject to the terms and conditions stated herein, to issue and sell from time to time through Jefferies LLC, as sales agent and/or principal (the “Age

Registration No. 333-241443

S-3 Table of Contents As filed with the Securities and Exchange Commission on August 6, 2020 Registration No.

Separation Agreement dated May 28, 2020 between the Registrant and Nick Glover

EX-10.2 3 d948272dex102.htm EX-10.2 Exhibit 10.2 [EXECUTION COPY] May 22, 2020 Dear Nick Glover: Re: Separation Agreement and Release This letter confirms the agreement (this “Agreement”) between Sierra Oncology, Inc. and Sierra Oncology Canada ULC (the “Company” and, collectively with Sierra Oncology, Inc. and each of their respective affiliates and subsidiaries, the “Company Group”) and you conc

Quarterly Report - 10-Q

10-Q UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ Quarterly Report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2020 OR ☐ Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to . Commission File Number: 001-37490 Sierra Oncolog

Registration Statement No. 333-241414, filed with the Commission on August 6, 2020, relating to the registration of 500,000 additional Shares under the 2018 Equity Inducement Plan;

S-8 As filed with the Securities and Exchange Commission on August 6, 2020 Registration No.

Form of Indenture

EX-4.3 Exhibit 4.3 SIERRA ONCOLOGY, INC. And , as Trustee INDENTURE Dated as of , TABLE OF CONTENTS ARTICLE 1 – DEFINITIONS AND INCORPORATION BY REFERENCE 1 1.1   DEFINITIONS 1 1.2.   OTHER DEFINITIONS 4 1.3.   INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT 4 1.4.   RULES OF CONSTRUCTION 4 ARTICLE 2 – THE SECURITIES 5 2.1.   ISSUABLE IN SERIES 5 2.2.   ESTABLISHMENT OF TERMS OF SERIES OF SECURI

2018 Equity Inducement Plan, as amended

EX-10.3 4 d948272dex103.htm EX-10.3 Exhibit 10.3 SIERRA ONCOLOGY, INC. 2018 EQUITY INDUCEMENT PLAN ADOPTED BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS: SEPTEMBER 2018 AMENDED BY THE BOARD OF DIRECTORS: JUNE 2020 1. PURPOSE. The purpose of this Plan is to provide incentives to attract, retain and motivate eligible persons whose present and potential contributions are important to the su

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 6, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissi

Sierra Oncology Reports Second Quarter 2020 Results - MOMENTUM Phase 3 clinical trial enrollment on track; top-line data anticipated in H1 2022 - - Updated analyses comparing symptomatic benefits of momelotinib to ruxolitinib from the SIMPLIFY-1 Phas

EX-99.1 Exhibit 99.1 Sierra Oncology Reports Second Quarter 2020 Results - MOMENTUM Phase 3 clinical trial enrollment on track; top-line data anticipated in H1 2022 - - Updated analyses comparing symptomatic benefits of momelotinib to ruxolitinib from the SIMPLIFY-1 Phase 3 trial anticipated in late 2020 - VANCOUVER, August 6, 2020 - Sierra Oncology, Inc. (SRRA), a late-stage drug development comp

Employment Agreement between the Registrant and Stephen G. Dilly

EX-10.1 Exhibit 10.1 EMPLOYMENT AGREEMENT Dear Stephen Dilly: This Employment Agreement (this “Agreement”) memorializes your employment terms with Sierra Oncology Inc., a Delaware corporation (the “Company”), effective as of your start date with the Company, expected to be June 1, 2020, or on such different date as mutually agreed upon by you and the Company (the date of your actual start date, th

Form of Debt Security

EX-4.2 Exhibit 4.2 FORM OF DEBT SECURITY [Face of Security] SIERRA ONCOLOGY, INC. [If applicable, insert—FOR PURPOSES OF THE ORIGINAL ISSUE DISCOUNT PROVISIONS OF THE INTERNAL REVENUE CODE OF 1986, THE ISSUE PRICE OF THIS SECURITY IS % OF ITS PRINCIPAL AMOUNT AT STATED MATURITY SET FORTH BELOW (ITS “PRINCIPAL AMOUNT”), THE AMOUNT OF ORIGINAL ISSUE DISCOUNT IS % OF ITS PRINCIPAL AMOUNT, THE YIELD T

Submission of Matters to a Vote of Security Holders

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 9, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 28, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 21, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

- DEFA14A

DEFA14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitt

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 7, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Sierra Oncology Reports First Quarter 2020 Results - Company continues to operationalize the MOMENTUM Phase 3 clinical trial in myelofibrosis - - Impact of COVID-19 uncertain but may potentially affect overall MOMENTUM timelines - - Publications high

EX-99.1 Exhibit 99.1 Sierra Oncology Reports First Quarter 2020 Results - Company continues to operationalize the MOMENTUM Phase 3 clinical trial in myelofibrosis - - Impact of COVID-19 uncertain but may potentially affect overall MOMENTUM timelines - - Publications highlighting durability, safety, and efficacy data for momelotinib planned throughout 2020 - VANCOUVER, May 7, 2020 - Sierra Oncology

Quarterly Report - 10-Q

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

82640U404 / Sierra Oncology Inc / Frazier Life Sciences Viii, L.p. - SC 13D/A Activist Investment

SC 13D/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13D UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 2)* Sierra Oncology, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 82640U404 (CUSIP Number) Steve R. Bailey Frazier Healthcare Partners 601 Union Street, Suite 3200 Seattle, WA 98101 Telephone: (206) 621-7200 (Name, Address and T

- DEFA14A

DEFA14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitt

Definitive Proxy Statement on Schedule 14A

DEF 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Financial Statements and Exhibits

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 14, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissi

Amended and Restated Bylaws

EX-3.1 Exhibit 3.1 SIERRA ONCOLOGY, INC., a Delaware Corporation AMENDED AND RESTATED BYLAWS As Amended and Restated on April 14, 2020 SIERRA ONCOLOGY, INC., a Delaware Corporation AMENDED AND RESTATED BYLAWS TABLE OF CONTENTS Article I - STOCKHOLDERS 1 Section 1.1: Annual Meetings 1 Section 1.2: Special Meetings 1 Section 1.3: Notice of Meetings 1 Section 1.4: Adjournments 1 Section 1.5: Quorum 1

Subsidiaries of the Registrant.

EX-21.1 EXHIBIT 21.1 LIST OF SUBSIDIARIES OF SIERRA ONCOLOGY, INC. Subsidiary Jurisdiction of Incorporation or Organization Sierra Oncology Canada ULC Canada, British Columbia

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 3, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissio

2015 Equity Incentive Plan, as amended, and forms of award agreements thereunder

EX-10.3 EXHIBIT 10.3 SIERRA ONCOLOGY, INC. 2015 EQUITY INCENTIVE PLAN As amended on January 21, 2020 1. PURPOSE. The purpose of this Plan is to provide incentives to attract, retain and motivate eligible persons whose present and potential contributions are important to the success of the Company, and any Parents and Subsidiaries that exist now or in the future, by offering them an opportunity to

Form 10-K

10-K Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

Registration Statement No. 333-236854, filed with the Commission on March 3, 2020, relating to the registration of 4,387,188 additional Shares under the 2015 Equity Incentive Plan;

S-8 As filed with the Securities and Exchange Commission on March 3, 2020 Registration No.

Exhibit 4.5

EX-4.5 EXHIBIT 4.5 DESCRIPTION OF CAPITAL STOCK General Our authorized capital stock consists of 500,000,000 shares of common stock, $0.001 par value per share, and 10,000,000 shares of undesignated preferred stock, $0.001 par value per share. The following description summarizes the most important terms of our capital stock. Because it is only a summary, it does not contain all the information th

Amendment to Asset Purchase Agreement dated October 28, 2019, by and between the Registrant and YM Biosciences Australia Pty Ltd. and Gilead Sciences, Inc.

EX-2.2 EXHIBIT 2.2 CERTAIN IDENTIFIED INFORMATION HAS BEEN OMITTED FROM THIS DOCUMENT BECAUSE IT IS BOTH NOT MATERIAL AND WOULD BE COMPETITIVELY HARMFUL IF PUBLICLY DISCLOSED, AND HAS BEEN MARKED WITH “[***]” TO INDICATE WHERE OMISSIONS HAVE BEEN MADE. AMENDMENT TO ASSET PURCHASE AGREEMENT This Amendment to the Asset Purchase Agreement (this “Amendment”) effective as of October 28, 2019 (the “Amen

Sierra Oncology Reports 2019 Year End Results - MOMENTUM Phase 3 clinical trial for momelotinib underway, targeting enrolment of 180 patients with myelofibrosis who are symptomatic and anemic - - Publications highlighting durability, safety and effic

EX-99.1 Exhibit 99.1 Sierra Oncology Reports 2019 Year End Results - MOMENTUM Phase 3 clinical trial for momelotinib underway, targeting enrolment of 180 patients with myelofibrosis who are symptomatic and anemic - - Publications highlighting durability, safety and efficacy data for momelotinib planned throughout 2020 - - Company to host analyst conference call at 8 am ET today - VANCOUVER, March

AGREEMENT REGARDING JOINT FILING OF SCHEDULE 13G

EX-99.1 EXHIBIT 1 AGREEMENT REGARDING JOINT FILING OF SCHEDULE 13G Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of shares of Common Stock of Sierra Oncology, Inc. Date: February 12, 2020 NEW LEAF V

SRRA / Sierra Oncology / Broadfin Capital, LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

SRRA / Sierra Oncology / Vivo Capital IX, LLC - AMENDMENT NO. 1 TO SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U404 (CUSIP Number) January 29, 2020 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursu

SRRA / Sierra Oncology / New Leaf Biopharma Opportunities I, L.p. - SC 13G/A Passive Investment

SC 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2 (Amendment No. 2) Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) December 31, 2019 (Date of

SRRA / Sierra Oncology / Longitude Capital Partners Iii, Llc - SC 13D/A Activist Investment

SC 13D/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1) SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U404 (CUSIP Number) Patrick G. Enright Managing Member Longitude Capital Partners III, LLC 2740 Sand Hill Road, 2nd Floor Menlo Park, CA 94025 (

SRRA / Sierra Oncology / GILEAD SCIENCES INC - SC 13G Passive Investment

SC 13G 1 a20-72271sc13g.htm SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G (Amendment No. )* Under the Securities Exchange Act of 1934 Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Titles of Class of Securities) 82640U404 (CUSIP Number) January 31. 2020 (Date of Event Which Requires Filing of this Statement) Check the

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT This Agreement will confirm the agreement by and among the undersigned that the Schedule 13D filed with the Securities and Exchange Commission on the date hereof with respect to the beneficial ownership by the undersigned of the Common Shares of Sierra Oncology, Inc.

SRRA / Sierra Oncology / Abingworth LLP - SIERRA 13D Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U404 (CUSIP Number) John Heard Abingworth LLP Princes House 38 Jermyn Street London, England SW1Y 6DN +44 20 7534 1500 (Name, Address and Telephone Number of

Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, Financial Statements and Exhibits

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 31, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

Securities Purchase Agreement by and between the Company and Gilead Sciences, Inc.

EX-10.1 Exhibit 10.1 SECURITY PURCHASE AGREEMENT This Security Purchase Agreement (this “Agreement”) is made as of January 31, 2020 (the “Effective Date”) by and between Sierra Oncology, Inc., a Delaware corporation (the “Company”), and Gilead Sciences, Inc., a Delaware corporation (the “Purchaser”). 1. Issuance of Securities. Effective as the Effective Date, the Company will issue to Purchaser (i

Form of Warrant to Gilead Sciences, Inc.

EX-10.2 Exhibit 10.2 THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR UNDER THE SECURITIES LAWS OF CERTAIN STATES. THESE SECURITIES MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED EXCEPT AS PERMITTED UNDER THE ACT AND APPLICABLE STATE SECURITIES LAWS IN ACCORDANCE WITH APPLICABLE REGISTRATION REQUIREM

SRRA / Sierra Oncology / CAXTON CORP Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

Certificate of Amendment to the Restated Certificate of Incorporation.

EX-3.1 Exhibit 3.1 CERTIFICATE OF AMENDMENT OF RESTATED CERTIFICATE OF INCORPORATION OF SIERRA ONCOLOGY, INC. Sierra Oncology, Inc., a corporation organized and existing under the laws of the State of Delaware (the “Corporation”), hereby certifies as follows: First: The name of the Corporation is Sierra Oncology, Inc. The Corporation’s original Certificate of Incorporation was filed with the Secre

Sierra Oncology Announces Reverse Stock Split - Preferred shares issued in recently completed $103M financing to convert to common shares - - Gilead to become shareholder in Sierra in accordance with amendment to Purchase Agreement -

EX-99.1 Exhibit 99.1 Sierra Oncology Announces Reverse Stock Split - Preferred shares issued in recently completed $103M financing to convert to common shares - - Gilead to become shareholder in Sierra in accordance with amendment to Purchase Agreement - VANCOUVER, January 22, 2020 - Sierra Oncology, Inc. (SRRA), a late-stage drug development company focused on the development and commercializatio

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Financial Statements and Exhibits, Other Events, Submission of Matters to a Vote of Security Holders

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 21, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 14, 2020 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

SRRA / Sierra Oncology / MANGROVE PARTNERS Passive Investment

SC 13G 1 efc20-54sc13g.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U107 (CUSIP Number) November 13, 2019 (Date of Event which Requires Filing of this Statement) Check the appropri

SRRA / Sierra Oncology DEF 14A - - DEF 14A

DEF 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

SRRA / Sierra Oncology PRE 14A - - PRE 14A

PRE 14A Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

SRRA / Sierra Oncology / ORBIMED ADVISORS LLC - SCHEDULE 13D Activist Investment

SC 13D 1 ss158552sc13d.htm SCHEDULE 13D UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 Sierra Oncology, Inc. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 82640U 10 7 (CUSIP Number) OrbiMed Advisors LLC OrbiMed Capital GP VII LLC OrbiMed Global Healthcare GP LLC OrbiMed Capital LLC 601 Lexington Avenue,

JOINT FILING AGREEMENT

Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the Statement on Schedule 13D, dated November 26, 2019, with respect to the ordinary shares of Sierra Oncology, Inc.

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 20, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commi

SRRA / Sierra Oncology / Vivo Opportunity, Llc - SCHEDULE 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 82640U107 (CUSIP Number) November 13, 2019 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuan

Exhibit 99.1

Exhibit 99.1 JOINT FILING AGREEMENT In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the Common Stock, $0.001 par value, of Sierra Oncology, Inc., and further agree that this Joint Filing Agreement be includ

JOINT FILING AGREEMENT

EX-99.1 Exhibit 1 JOINT FILING AGREEMENT The undersigned hereby agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned, and any amendments thereto executed by the undersigned shall be filed on behalf of each of the undersigned without the necessity of filing any additional joint filing agreement. The undersigned acknowledge that each is responsible for the

SRRA / Sierra Oncology / Longitude Capital Partners Iii, Llc - SC 13D Activist Investment

SC 13D SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. ) SIERRA ONCOLOGY, INC. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U 10 7 (CUSIP Number) Patrick G. Enright Managing Member Longitude Capital Partners III, LLC 2740 Sand Hill Road, 2nd Floor Menlo Park, CA 94025 (6

SRRA / Sierra Oncology / Venrock Healthcare Capital Partners Ii, L.p. - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Sierra Oncology, Inc. (Name of Issuer) Common Stock, par value $0.001 per share (Title of Class of Securities) 82640U107 (CUSIP Number) November 13, 2019 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the ru

Form of Series A Convertible Voting Preferred Stock Certificate

EX-4.1 Exhibit 4.1 Number Shares *PR A- * Sierra Oncology, Inc. * * Incorporated Under the Laws of the State of Delaware CUSIP 82640U 20 6 SEE REVERSE FOR CERTAIN DEFINITIONS This certifies that Is the record holder of * ( )* FULLY PAID AND NONASSESSABLE SHARES OF SERIES A PREFERRED STOCK $0.001 PAR VALUE PER SHARE, OF SIERRA ONCOLOGY, INC. transferable on the books of the corporation in person or

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Entry into a Material Definitive Agreement, Financial Statements and Exhibits

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 13, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commi

Certificate of Designation of Preferences, Rights and Limitations, with respect to the Series A Convertible Voting Preferred Stock.

EX-3.1 Exhibit 3.1 SIERRA ONCOLOGY, INC. CERTIFICATE OF DESIGNATION OF PREFERENCES, RIGHTS AND LIMITATIONS OF SERIES A CONVERTIBLE VOTING PREFERRED STOCK PURSUANT TO SECTION 151 OF THE DELAWARE GENERAL CORPORATION LAW SIERRA ONCOLOGY, INC., a Delaware corporation (the “Corporation”), in accordance with the provisions of Section 103 of the Delaware General Corporation Law (the “DGCL”) does hereby c

103,000 Shares of Series A Convertible Voting Preferred Stock 312,090,000 Series A Warrants 312,090,000 Series B Warrants (and 727,169,700 shares of common stock underlying shares of Series A Convertible Voting Preferred Stock, Series A Warrants and

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-225650 PROSPECTUS SUPPLEMENT (To Prospectus dated June 21, 2018) 103,000 Shares of Series A Convertible Voting Preferred Stock 312,090,000 Series A Warrants 312,090,000 Series B Warrants (and 727,169,700 shares of common stock underlying shares of Series A Convertible Voting Preferred Stock, Series A Warrants and Series

Form of Series B Warrant

EX-4.2 Exhibit 4.2 SIERRA ONCOLOGY, INC. SERIES B WARRANT TO PURCHASE COMMON STOCK Number of Warrants: Warrant No.: [ ] Number of Warrant Shares: Date of Issuance: November [ ], 2019 (“Issuance Date”) Expiration Date: Seventy-fifth (75th) day anniversary of the Company’s (as defined below) announcement, via publicly disseminated press release or SEC filing, of the top-line data results from MOMENT

Sierra Oncology Announces Pricing of $103 Million Public Offering of Convertible Preferred Stock and Warrants

EX-99.1 Exhibit 99.1 Sierra Oncology Announces Pricing of $103 Million Public Offering of Convertible Preferred Stock and Warrants Vancouver – November 7, 2019. Sierra Oncology, Inc. (Nasdaq: SRRA), a late-stage drug development company focused on the development and commercialization of momelotinib, a JAK1, JAK2 & ACVR1 inhibitor with a potentially differentiated therapeutic profile for the treat

Form of Certificate of Designation of Preferences, Rights and Limitations of Series A Convertible Voting Preferred Stock

EX-3.1 Exhibit 3.1 SIERRA ONCOLOGY, INC. CERTIFICATE OF DESIGNATION OF PREFERENCES, RIGHTS AND LIMITATIONS OF SERIES A CONVERTIBLE VOTING PREFERRED STOCK PURSUANT TO SECTION 151 OF THE DELAWARE GENERAL CORPORATION LAW SIERRA ONCOLOGY, INC., a Delaware corporation (the “Corporation”), in accordance with the provisions of Section 103 of the Delaware General Corporation Law (the “DGCL”) does hereby c

Form of Series A Warrant

EX-4.1 Exhibit 4.1 SIERRA ONCOLOGY, INC. SERIES A WARRANT TO PURCHASE COMMON STOCK Number of Warrants: Warrant No.: [] Number of Warrant Shares: Date of Issuance: November [], 2019 (“Issuance Date”) Expiration Date: Five (5) year anniversary of the Exercisability Date (“Expiration Date”) Sierra Oncology, Inc., a Delaware corporation (the “Company”), certifies that, for good and valuable considerat

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Other Events

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 7, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

Underwriting Agreement, dated November 7, 2019

EX-1.1 Exhibit 1.1 Sierra Oncology, Inc. UNDERWRITING AGREEMENT 103,000 Shares of Series A Preferred Stock Series A Warrants Series B Warrants November 7, 2019 JEFFERIES LLC As Representative of the several Underwriters c/o JEFFERIES LLC 520 Madison Avenue New York, New York 10022 Ladies and Gentlemen: Introductory. Sierra Oncology, Inc., f/k/a ProNAi Therapeutics, Inc., a Delaware corporation (th

Pricing Term Sheet Sierra Oncology, Inc. Series A Convertible Voting Preferred Stock Series A Warrants Series B Warrants (and shares of common stock underlying shares of Series A Convertible Voting Preferred Stock, Series A Warrants and Series B Warr

FWP Issuer Free Writing Prospectus, dated November 7, 2019 Filed Pursuant to Rule 433 of the Securities Act of 1933 Registration Statement No.

SRRA / Sierra Oncology S-3MEF - - S-3MEF

S-3MEF 1 d830368ds3mef.htm S-3MEF As filed with the Securities and Exchange Commission on November 7, 2019 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-3 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 2834 20-0138994 (State or other jurisdiction of

Shares of Series A Convertible Voting Preferred Stock Series A Warrants Series B Warrants (and shares of common stock underlying shares of Series A Convertible Voting Preferred Stock, Series A Warrants and Series B Warrants)

424B5 Table of Contents Filed Pursuant to Rule 424(b)(5) Registration No. 333-225650 The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission and is effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to

Form 10-Q

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 4, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

Sierra Oncology Reports Third Quarter 2019 Results - MOMENTUM Phase 3 myelofibrosis clinical trial anticipated to launch in Q4 2019 -

EX-99.1 Exhibit 99.1 Sierra Oncology Reports Third Quarter 2019 Results - MOMENTUM Phase 3 myelofibrosis clinical trial anticipated to launch in Q4 2019 - VANCOUVER, November 4, 2019 — Sierra Oncology, Inc. (SRRA), a late-stage drug development company focused on advancing targeted therapeutics for the treatment of patients with significant unmet needs in hematology and oncology, today reported it

Sierra Oncology Reports Second Quarter 2019 Results - Sierra preparing to launch the MOMENTUM Phase 3 myelofibrosis clinical trial expected in Q4 2019 - - Exploring non-dilutive options to support future continued development of DDR portfolio -

EX-99.1 Exhibit 99.1 Sierra Oncology Reports Second Quarter 2019 Results - Sierra preparing to launch the MOMENTUM Phase 3 myelofibrosis clinical trial expected in Q4 2019 - - Exploring non-dilutive options to support future continued development of DDR portfolio - VANCOUVER, Aug 8, 2019 - Sierra Oncology, Inc. (SRRA), a late-stage drug development company focused on advancing targeted therapeutic

Financial Statements and Exhibits, Results of Operations and Financial Condition

Form 8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 8, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Com

Form 10-Q

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 16, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commissio

Submission of Matters to a Vote of Security Holders

Form 8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 11, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Comm

Sierra Announces FDA Regulatory Clarity for Momelotinib & Design of the MOMENTUM Phase 3 Clinical Trial - MOMENTUM Phase 3 clinical trial planned for launch in Q4 2019; topline efficacy data anticipated in Q4 2021 – - World renowned myelofibrosis exp

EX-99.1 Exhibit 99.1 Sierra Announces FDA Regulatory Clarity for Momelotinib & Design of the MOMENTUM Phase 3 Clinical Trial - MOMENTUM Phase 3 clinical trial planned for launch in Q4 2019; topline efficacy data anticipated in Q4 2021 – - World renowned myelofibrosis expert Dr. Srdan Verstovsek named Chief Investigator of the MOMENTUM Phase 3 study - - 180 patient 2:1 randomized, double blind clin

Sierra Announces Momelotinib Granted FDA Fast Track Designation - Fast Track designation highlights the potential for momelotinib to address the significant unmet needs of patients with Intermediate/High-Risk myelofibrosis who have previously receive

EX-99.2 Exhibit 99.2 Sierra Announces Momelotinib Granted FDA Fast Track Designation - Fast Track designation highlights the potential for momelotinib to address the significant unmet needs of patients with Intermediate/High-Risk myelofibrosis who have previously received a JAK inhibitor - - Fast Track Designation assures frequent communication with FDA, often leading to earlier drug approval and

Financial Statements and Exhibits, Other Events

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 4, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Sierra Announces Promising Preliminary Efficacy in SRA737 Clinical Program & Outlines Potential Path to Registration - Sierra reports 30% response rate for SRA737+LDG in anogenital cancer - - Anti-cancer activity demonstrated across multiple indicati

EX-99.1 Exhibit 99.1 Sierra Announces Promising Preliminary Efficacy in SRA737 Clinical Program & Outlines Potential Path to Registration - Sierra reports 30% response rate for SRA737+LDG in anogenital cancer - - Anti-cancer activity demonstrated across multiple indications and genetic contexts in preliminary Phase 1/2 data presentations at ASCO – - Sierra to discuss clinical findings and possible

Financial Statements and Exhibits, Other Events

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 1, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 8, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commission

Sierra Oncology Reports First Quarter 2019 Results - Momelotinib regulatory pathway clarity anticipated in Q2 2019 - - SRA737 Phase 1/2 preliminary clinical data anticipated at the 2019 ASCO Annual Meeting -

EX-99.1 Exhibit 99.1 Sierra Oncology Reports First Quarter 2019 Results - Momelotinib regulatory pathway clarity anticipated in Q2 2019 - - SRA737 Phase 1/2 preliminary clinical data anticipated at the 2019 ASCO Annual Meeting - Vancouver - May 8, 2019. Sierra Oncology, Inc. (“Sierra Oncology”) (Nasdaq: SRRA), a clinical stage drug development company focused on advancing targeted therapeutics for

Form 10-Q

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

SRRA / Sierra Oncology DEFINITIVE ADDITIONAL MATERIALS

DEFA14A 1 d732747ddefa14a.htm DEFINITIVE ADDITIONAL MATERIALS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Rule 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Co

Schedule 14A

Definitive Proxy Statement Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.

Registration Statement No. 333-229933, filed with the Commission on February 28, 2019, relating to the registration of 2,974,638 additional Shares under the 2015 Equity Incentive Plan;

S-8 As filed with the Securities and Exchange Commission on February 28, 2019 Registration No.

Sierra Oncology Reports 2018 Year End Results - Momelotinib regulatory pathway clarity anticipated in H1 2019 - - SRA737 preliminary data anticipated in H1 2019 -

EX-99.1 Exhibit 99.1 Sierra Oncology Reports 2018 Year End Results - Momelotinib regulatory pathway clarity anticipated in H1 2019 - - SRA737 preliminary data anticipated in H1 2019 - VANCOUVER, February 28, 2019 — Sierra Oncology, Inc. (Nasdaq: SRRA), a clinical stage drug development company focused on advancing targeted therapeutics for the treatment of patients with significant unmet needs in

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K 1 d710768d8k.htm 8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 28, 2019 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of

Form 10-K

10-K Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

Subsidiaries of the Registrant.

EX-21.1 EXHIBIT 21.1 LIST OF SUBSIDIARIES OF SIERRA ONCOLOGY, INC. Subsidiary Jurisdiction of Incorporation or Organization Sierra Oncology Canada ULC Canada, British Columbia

SRRA / Sierra Oncology / PERCEPTIVE ADVISORS LLC - SC 13G/A Passive Investment

SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U 10 7 (CUSIP Number) December 31, 2018 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to desi

SRRA / Sierra Oncology / Broadfin Capital, LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

AGREEMENT REGARDING JOINT FILING OF SCHEDULE 13G

EX-99.1 EXHIBIT 1 AGREEMENT REGARDING JOINT FILING OF SCHEDULE 13G Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of shares of Common Stock of Sierra Oncology, Inc. Date: February 12, 2019 NEW LEAF B

SRRA / Sierra Oncology / ORBIMED ADVISORS LLC - SCHEDULE 13G HOLDINGS REPORT AMENDMENT Passive Investment

SC 13G/A 1 orbimed-srra123118a1.htm SCHEDULE 13G HOLDINGS REPORT AMENDMENT UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock, Par Value $0.001 Per Share (Title of Class of Securities) 82640U107 (CUSIP Number) December 31, 2018 (Date of Event Which Requ

SRRA / Sierra Oncology / New Leaf Biopharma Opportunities I, L.p. - SC 13G/A Passive Investment

SC 13G/A 1 d700844dsc13ga.htm SC 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2 (Amendment No. 1) Sierra Oncology, Inc. (Name of Issuer) Common Stock, $0.001 par value per share (Title of Class of Securities) 82640U107 (CUSIP Numbe

SRRA / Sierra Oncology / Frazier Life Sciences Viii, L.p. - SCHEDULE 13D/A (AMENDMENT NO. 1) Activist Investment

Schedule 13D/A (Amendment No. 1) UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13D UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. 1)* Sierra Oncology, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 74346L101 (CUSIP Number) Steve R. Bailey Frazier Healthcare Partners 601 Union Street, Suite 3200 Seattle, WA 98101 Telephone: (206) 621-7

Registration Statement No. 333-228263, filed with the Commission on November 8, 2018, relating to the registration of 1,500,000 Shares under the 2018 Equity Inducement Plan;

S-8 As filed with the Securities and Exchange Commission on November 8, 2018 Registration No.

Financial Statements and Exhibits, Results of Operations and Financial Condition

8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 8, 2018 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001- 37490 20-0138994 (State or other jurisdiction of incorporation) (Commis

Sierra Oncology Reports Third Quarter Results - Momelotinib regulatory pathway clarity anticipated in H1 2019 - - SRA737 Monotherapy and LDG Combination trial preliminary data anticipated in H1 2019 -

EX-99.1 Exhibit 99.1 Sierra Oncology Reports Third Quarter Results - Momelotinib regulatory pathway clarity anticipated in H1 2019 - - SRA737 Monotherapy and LDG Combination trial preliminary data anticipated in H1 2019 - VANCOUVER, November 8, 2018—Sierra Oncology, Inc. (Nasdaq: SRRA), a clinical stage drug development company focused on advancing targeted therapeutics for the treatment of patien

Warrant dated August 21, 2018 issued to Silicon Valley Bank

EX-4.1 Exhibit 4.1 THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AS SET FORTH IN SECTIONS 5.3 AND 5.4 BELOW, MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND LAWS OR IN FORM AND SUBSTANCE SATISFACTORY TO THE COM

Loan and Security Agreement dated August 21, 2018, by and between the Registrant and Silicon Valley Bank.

EX-10.1 EXHIBIT 10.1 [***] Certain confidential information contained in this document, marked by brackets, has been omitted and filed separately with the Securities and Exchange Commission pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. LOAN AND SECURITY AGREEMENT THIS LOAN AND SECURITY AGREEMENT (this “Agreement”) dated and effective as of August 21, 2018 (the “Effecti

2018 Equity Inducement Plan and forms of award agreements thereunder.

EX-10.2 Exhibit 10.2 SIERRA ONCOLOGY, INC. 2018 EQUITY INDUCEMENT PLAN 1. PURPOSE. The purpose of this Plan is to provide incentives to attract, retain and motivate eligible persons whose present and potential contributions are important to the success of the Company, and any Parents and Subsidiaries that exist now or in the future, by offering them an opportunity to participate in the Company’s f

SRRA / Sierra Oncology 10-Q (Quarterly Report)

10-Q Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

Asset Purchase Agreement dated August 20, 2018 by and between the Registrant and YM Biosciences Australia Pty Ltd. and Gilead Sciences, Inc.

EX-2.1 EXHIBIT 2.1 [***] Certain confidential information contained in this document, marked by brackets, has been omitted and filed separately with the Securities and Exchange Commission pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. Execution Version ASSET PURCHASE AGREEMENT by and among SIERRA ONCOLOGY, INC., YM BIOSCIENCES AUSTRALIA PTY LTD, and GILEAD SCIENCES, INC

SRRA / Sierra Oncology / Broadfin Capital, LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant, Completion of Acquisition or Disposition of Assets

8-K 1 d612613d8k.htm 8-K UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 20, 2018 SIERRA ONCOLOGY, INC. (Exact name of registrant as specified in its charter) Delaware 001-37490 20-0138994 (State or other jurisdiction of inc

Sierra Oncology Acquires Momelotinib, an Investigational Janus Kinase (JAK) 1/2 and Activin Receptor Type 1 (ACVR1) Inhibitor for Myelofibrosis, from Gilead Sciences - More than 1,200 patients treated to date with momelotinib, including in two Phase

EX-99.1 Exhibit 99.1 Sierra Oncology Acquires Momelotinib, an Investigational Janus Kinase (JAK) 1/2 and Activin Receptor Type 1 (ACVR1) Inhibitor for Myelofibrosis, from Gilead Sciences - More than 1,200 patients treated to date with momelotinib, including in two Phase 3 trials; ongoing therapy for more than seven years in some patients - - Demonstrated meaningful anemia-related benefits - - Subs