Sierra Oncology, Inc. is a biopharmaceutical firm focused on the late-stage research, development, and commercialization of therapeutic solutions for patients with blood disorders and various cancers. The company's primary drug candidate is momelotinib, an orally administered, selective inhibitor that targets Janus kinase 1 (JAK1), JAK2, and Activin A receptor type 1 (ACVR1). Additionally, its pipeline includes SRA515, a selective bromodomain-containing protein 4 inhibitor, and SRA737, an orally bioavailable small molecule designed to inhibit Checkpoint kinase 1. Sierra Oncology maintains license agreements with partners such as Carna Biosciences, Inc. for the development and commercialization of SRA141 (a small molecule kinase inhibitor targeting Cdc7), along with AstraZeneca AB and CRT Pioneer Fund LP. Established in 2003, the company was initially known as ProNAi Therapeutics, Inc. before rebranding to Sierra Oncology, Inc. in January 2017. Headquartered in San Mateo, California, Sierra Oncology, Inc. has been operating as a subsidiary of GSK plc since July 1, 2022.