Zafgen reports second death in Phase III trial of ZAF-311 (beloranib), a proposed treatment for Prader-Willi syndrome

Zafgen provided an update on the open label extension (OLE) portion of the pivotal Phase III ZAF-311 (beloranib) bestPWS clinical trial evaluating beloranib in patients with Prader-Willi syndrome (PWS). On 1 December 2015, the Company learned that a patient receiving beloranib as part of the OLE portion of the study was diagnosed with bilateral pulmonary emboli and has died. As previously announced, the Company continues to expect top-line results of the randomised portion of the ZAF-311 clinical trial in the first quarter of 2016.

Comment: This is the second patient to have died in the trial and in this case from bilateral pulmonary emboli. Zafgen has been investigating the first death and is screening patients for thromboembolic events. The drug has a significant effect on weight loss similar to the effect of gastric bypass surgery but safety must be the major concern of the company now.