Sierra Oncology Acquires Gilead’s Stalled Myelofibrosis Drug

Xconomy Seattle — 

An experimental myelofibrosis drug that fell short of expectations for Gilead Sciences is getting another shot under Sierra Oncology.

Vancouver, BC-based Sierra (NASDAQ: SRRA) has acquired the drug, momelotinib, from Gilead (NASDAQ: GILD), for $3 million up front. The deal adds a late-stage drug candidate to Sierra’s pipeline of early-stage cancer drugs. Meanwhile, Foster City, CA-based Gilead, gains a way to salvage something from the $510 million acquisition of YM Biosciences in 2012, which brought it momelotinib. If Sierra can bring the drug to the market, Gilead stands to gain as much as $195 million in milestone payments, plus royalties from sales.

Myelofibrosis is a bone marrow cancer that leads patients to develop anemia, weakness, and an enlarged spleen and liver. Between 50 percent and 60 percent of myelofibrosis patients have a mutation of the Janus kinase 2 gene (JAK2), according to the Leukemia & Lymphoma Society. The mutations can cause abnormal signals in the pathways governing the bone marrow’s production of blood cells.

The pain and discomfort that myelofibrosis patients feel is due in part to an enlarged spleen. Ruxolitinib (Jakafi), a JAK inhibitor marketed by Incyte (NASDAQ: INCY), reduces spleen size. Gilead had hoped its drug would offer the advantage of improving anemia symptoms in addition to reducing spleen size. The company advanced momelotinib, which is also a JAK inhibitor, into late-stage clinical trials. But in 2016, the company reported mixed results from two Phase 3 studies that compared its drug to Incyte’s. Though momelotinib reduced spleen size, it did not sufficiently distance itself from the Incyte drug in measures of anemia symptoms.

There are other companies developing myelofibrosis drugs. Seattle-based CTI BioPharma (NASDAQ: CTIC) has advanced its JAK inhibitor, pacritinib, into mid-stage studies. Imetelstat, a drug from Menlo Park, CA-based Geron takes a different approach, blocking an enzyme called telomerase. That drug is currently in Phase 2 studies testing it in patients who have relapsed or whose cancer has spread following treatment with a JAK inhibitor.

Sierra’s momelotinib acquisition represents a reunion of sorts. The company’s CEO, Nick Glover, led YM Biosciences when it was acquired by Gilead. Mark Kowalski, Sierra’s chief medical officer, is YM’s former CMO. In a prepared statement, Glover said that Sierra will likely need to conduct another clinical trial testing momelotinib and the company plans to meet with the FDA to discuss the drug’s regulatory pathway. In the meantime, Sierra has secured up to $15 million in debt financing from Silicon Valley Bank for the acquisition and future development of momelotinib. Sierra may borrow an additional $25 million, if the bank approves.

Photo by Flickr user JamesZ_Flickr via a Creative Commons license