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Epizyme’s Blood Cancer Drug Studies Will Continue; Shares Fall

Shares of Epizyme Inc. fell Monday after investors were disappointed that preliminary data from the company’s mid-stage study of its blood cancer drug didn’t live up to the high expectations set by an earlier trial.

The drugmaker presented data Sunday showing that 28 percent of 47 patients whose results were available had their cancer disappear or shrink. That’s less than the 60 percent of patients who responded in an earlier stage test, Simos Simeonidis, an analyst with RBC Capital Markets, said in a note to clients. The mid-stage trial is still under way.

The stock fell as much as 9.6 percent, the biggest intraday drop since March 23. It was down 3.9 percent to $10.99 at 10:44 a.m. in New York. Simeonidis said the response rates could improve as more data are collected from the phase 2 trial.

Epizyme’s drug, called tazemetostat, is being tested in five groups of patients with different types of non-Hodgkin’s lymphoma who relapsed after taking other therapies. Testing in four of the groups will continue, and more data is needed to decide whether to continue the trial in a fifth patient group, the company said.

There will be about 73,000 new cases of non-Hodgkin’s lymphoma in the U.S. this year, according to the U.S. National Institutes of Health, and roughly 29 percent of patients die within five years of diagnosis. The trial was conducted in patients who had already undergone and stopped responding to aggressive cancer therapy and, while the data are still early, the results have been similar to earlier-stage tests, said Peter Ho, Epizyme’s chief medical officer.

Safety Data

“This is a very advanced and heavily pre-treated population of cancer patients,” Ho said by phone. “What we’re finding is that the very favorable safety profile that was in phase 1 is being replicated in phase 2.” 

Epizyme, based in Cambridge, Massachusetts, has no approved therapies and tazemetostat is its most advanced experimental drug.

Among 47 patients whose disease data were available, four had their tumors eliminated and nine saw tumor shrinkage, according to the statement. One patient whose tumor shrank has since started seeing regrowth, according to slides that will be presented at the American Society of Hematology Meeting on Lymphoma Biology in Colorado Springs, Colorado. Among 82 patients for whom safety data were available, 2 percent stopped taking tazemetostat because of drug-related side effects. The most common severe side effects were low white blood cell counts and platelet deficiencies.