Zafgen shares plunge as another fatality reported with beloranib

Shares of Boston, USA-based biotech firm Zafgen (Nasdaq: ZFGN) plunged as much as 57% to $6.95 in pre-market trading this morning, after the company reported that another patient with a very rare disease called Prader-Willi syndrome who took part in a trial of the company's obesity drug candidate beloranib has died due to a blood clot.

In a statement this morning, the company said it had learned the day earlier that a patient receiving beloranib as part of the open label extension (OLE) portion of the Phase III study was diagnosed with bilateral pulmonary emboli and has died.

The company said it is discussing its next steps for development of the drug with the Food and Drug Administration, but added that it continues to expect top-line results of the randomized portion of the ZAF-311 clinical trial in the first quarter of 2016.