Sunesis shares crushed in a rout after leukemia PhIII ends in defeat

Shares of South San Francisco-based Sunesis ($SNSS) were crushed this morning after the biotech put out word that its drug vosaroxin had flunked a Phase III test for acute myeloid leukemia. The stock plunged about 70% on the news that the experimental therapy had failed to significantly improve survival rates compared to a placebo.

Patients in the drug arm combined with cytarabine posted a median OS rate of 7.5 months compared to 6.1 months for the placebo arm of the study. But after slicing the data by age and excluding patients who had undergone a stem cell transplant, the biotech did its best to pluck success from the open mouth of a defeat.

Those over 60 did better, according to the biotech, which the company believes is enough with the transplant qualifier to file for an approval in Europe.  For some reason the placebo arm in the analysis excluding patients who had undergone stem cell transplants experienced a shorter survival rate, helping vosaroxin in the comparison. 

Talks are planned with the FDA. Investors, though, weren't in a forgiving mood after reviewing the data on the primary endpoint. Another complicating factor: Investigators tracked a significantly higher rate of serious adverse events among patients--55.5% in the vosaroxin combination arm compared to 35.7% in the placebo and cytarabine arm. 

Robert Stuart

"VALOR was a robust, well-conducted trial, among the largest in the relapsed or refractory AML setting. The study outcomes are very encouraging, and I look forward to a full presentation of the data in a peer-reviewed forum," said Robert Stuart, a professor at Medical University of South Carolina and an investigator in the VALOR study. "The clinical benefit is particularly impressive in patients aged 60 years and older, a population for whom there is no therapeutic standard of care."

- here's the release

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