1. The Company and Basis of Presentation Organization and Description of Business Sierra Oncology, Inc. (together with its subsidiaries, collectively referred to as the Company), a Delaware corporation, is 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 needs in myelofibrosis. Momelotinib is a selective and orally-bioavailable JAK1 (Janus kinase 1), JAK2 (Janus kinase 2) and ACVR1 (Activin A receptor type 1) inhibitor with a differentiated mechanism of action that enables it to potentially address all three key drivers of myelofibrosis: anemia of inflammation, constitutional symptoms and enlarged spleen. More than 1,200 subjects have received momelotinib since clinical studies began in 2009, including more than 800 patients treated for myelofibrosis. Several of these patients remain on treatment for more than 10 years. The Companys portfolio also includes SRA737, a selective, orally bioavailable small molecule inhibitor of Checkpoint kinase 1 (Chk1), an emerging target for the treatment of cancer which has a key role in the DNA Damage Response (DDR). The Company is currently focusing its resources on the development of momelotinib and exploring options to support any future continued development of SRA737. The Companys primary activities since inception have been conducting research and development activities, conducting preclinical and clinical testing, recruiting personnel, performing business and financial planning, identifying and evaluating additional drug candidates for potential in-licensing or acquisition, and raising capital to support development activities. The Company has not generated any product revenue related to its primary business purpose to date, nor has it generated any net income, and is subject to a number of risks and uncertainties, which include dependence on key individuals, the need to identify and successfully develop commercially viable products, the need to obtain regulatory approval for its products and commercialize them, and the need to obtain adequate additional financing to fund the development of momelotinib. As of September 30, 2020, the Company had $109.0 million of cash and cash equivalents. The Company believes that its balance of cash and cash equivalents as of the date of the issuance of these condensed consolidated financial statements is sufficient to fund its current operational plan for at least the next twelve months, though it may pursue raising additional capital through equity financings or other arrangements. Reverse Stock Split On January 21, 2020, the Companys shareholders approved an amendment to the Companys certificate of incorporation to effect a reverse split of the Companys common stock (Reverse Stock Split). On January 21, 2020, the Companys board of directors approved the specific ratio for the Reverse Stock Split, which became effective on January 22, 2020, at 1-for-40. The authorized shares and par value of the common and preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, warrants for common stock, options for common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented.