Sierra Oncology, Inc., formerly ProNAi Therapeutics, Inc., is a clinical-stage drug development company. The Company’s lead drug candidate, SRA737, is orally bioavailable small molecule inhibitor of Checkpoint kinase 1 (Chk1), a key cell cycle checkpoint and central regulator of the deoxyribonucleic acid (DNA) Damage Response (DDR) network. SRA737 is being investigated in approximately two Phase I clinical trials in patients with advanced cancer. Sierra Oncology is also advancing SRA141, an orally bioavailable small molecule inhibitor of the cell division cycle 7 kinase (Cdc7) kinase undergoing preclinical development. Sierra is building a range of pipeline of various oncology assets against targets at the edge of cancer biology. The Company’s SRA737 and SRA141 target the DDR network, a scientifically approach with far-reaching potential across oncology. SRA141 is an orally available small molecule inhibitor of Cdc7.