Sunesis dives as company plans to focus on getting Qinprezo approved in EU; FDA wants new data

Shares of Sunesis Pharmaceuticals plunged in aftermarket trading Thursday after the company said it will focus on trying to get its blood cancer drug Qinprezo on the market in Europe because regulators in the U.S. won't approve it based on available data.

Sunesis said European regulators suggested it seek marketing approval for Qinprezo in patients 60 years and older because they need a new treatment the most, and benefited the most from treatment with the drug during the company's late-stage clinical trial. If the drug were approved only for elderly patients, that would likely limit its use. Sunesis has been studying the drug as a treatment for acute myeloid leukemia in patients who have suffered a relapse or whose cancer did not respond to previous treatment.

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The Food and Drug Administration doesn't support a filing, Sunesis said. It said the agency wants to see more clinical evidence supporting the drug. The South San Francisco, California-based company said it will evaluate and refine its plans for marketing the drug in the U.S.

Sunesis shares fell $2.16, or about 62 percent, to $1.31 in aftermarket trading.

In October the company said Qinprezo, or vosaroxin, didn't meet its main goal in a late-stage study. Patients who were treated with the drug and the chemotherapy drug cytarabine did not survive significantly longer than patients who were given cytarabine and a placebo.

Shares of Sunesis Pharmaceuticals Inc. tumbled 78 percent on Oct. 6, the day those results were announced, and closed at $1.46. The stock has gradually recovered since then and closed at $3.47 on Thursday.