Zafgen Obesity Drug Trial on Hold After Patient Deaths

  • Company says patient died of blood blockages in the lungs
  • U.S. Food and Drug Administration stops trial from continuing

Zafgen Inc. said its trial of an experimental drug to fight obesity was placed on hold by U.S. regulators after a second patient died.

The trial, in patients with a rare genetic disease called Prader-Willi syndrome that causes overeating, was a key study Zafgen needed to finish leading up to a U.S. Food and Drug Administration decision on whether to approve the drug for those patients.

While Zafgen had finished the part of the trial that compared effects of the drug to a placebo, it continued with an extension phase in which all the patients took the drug. The FDA ordered a complete clinical hold, meaning Zafgen must stop this extension phase and all other clinical work on the drug, the drugmaker said Wednesday in a statement.

Earlier in the day, Zafgen said a patient on the drug, beloranib, died of blood blockages in the lungs, sending the company’s shares plunging 61 percent to $6.28 at the New York close. The stock continued to slide in late trading after news of the FDA’s trial hold, dropping 13 percent to $5.49 at 7:59 p.m. New York time.

“We are working diligently to assemble and analyze the data from our ZAF-311 clinical trial to be able to provide a clear view of the safety and efficacy of beloranib” for Prader-Willi syndrome patients, said Thomas Hughes, Zafgen’s chief executive officer, in a statement. “We remain committed to advancing beloranib as a potential new therapy for this underserved patient population.”

Second Fatality

It’s the second patient death on the drug, Zafgen’s only experimental product being tested in people. In October, the Boston-based company said a trial patient had died of respiratory failure due to blood clots in the lungs, and said it was ending the randomized part of the study early.

The drug, which works by helping the body metabolize fat, has been tested in two other types of obesity. Prader-Willi syndrome gives patients an insatiable appetite and leads to chronic overeating, and can cause delayed development. The condition has a high rate of mortality linked to obesity and its related conditions, according to the company.

Zafgen said Wednesday that it still expects results from the randomized portion of the trial in the first three months of next year.

(Corrects trial status in second paragraph, cause of death in sixth paragraph.)
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