BOTHELL — OncoGenex Pharmaceuticals, a biotech firm developing cancer treatments in Bothell, is merging with California pharmaceutical company Achieve Life Science.

The combined company will take on the Achieve Life Science name. Achieve equity holders will own 75 percent of the combined company’s outstanding shares and current OncoGenex stockholders will own 25 percent upon completion of the proposed merger.

“After extensive and thorough review of strategic alternatives, we are very pleased to announce this proposed merger with Achieve as it adds both immediate and long-term product opportunities in indications with significant patient need and commercial opportunity,” said Scott Cormack, President and CEO of OncoGenex, in a statement.

OncoGenex is a publicly traded company. The company is developing cancer treatments, but one, prostate cancer drug custirsen, failed in clinical test announced last summer to show “significant improvements in overall survival of patients.”

Achieve Life Science is a privately held company that is developing a smoking cessation aid with cystisine, a plant-based alkyloid with a high binding affinity to the nicotinic acetylcholine receptor. It is an established smoking cessation treatment that has been approved and marketed in Central and Eastern Europe for more than 15 years, according to the statement.

The proposed merger will create a clinical-stage company focused on clinical and commercial development of cytisine.

“With cytisine in late-stage development for smoking cessation and having a defined regulatory path with FDA, we believe the proposed merger provides our stockholders with an opportunity to realize value from their investment in OncoGenex,” McCormack said.

Prior to the completion of the proposed merger, OncoGenex is expected to distribute to its stockholders contingent value rights for 80 percent of any net proceeds of certain payments arising from a future sale, transfer, license or similar transaction involving OncoGenex’s apatorsen cancer treatment, which is still in trials.

Rick Stewart, chairman of Achieve, said in the statement, “Achieve is expecting to meet a number of significant clinical and regulatory milestones within the next 12 to 18 months culminating in a final, large-scale Phase 3 clinical trial. The merger of OncoGenex and Achieve provides additional clinical and corporate resources to meet those milestones.”

The combined company’s executive management team will be led by Rick Stewart, chairman of Achieve; Anthony Clarke, chief scientific officer of Achieve; John Bencich, chief financial officer of OncoGenex; and Cindy Jacobs, chief medical officer of OncoGenex.