Phase III trial of ZGN 433 (beloranib) in Prader-Willi syndrome meets endpoints- Zafgen

Zafgen announced positive efficacy results from the bestPWS ZAF-311 study, a pivotal, double-blind, placebo-controlled Phase III trial evaluating the safety and efficacy of ZGN 433 (beloranib) in patients with Prader-Willi syndrome (PWS) during a six-month randomized treatment period. The clinical trial achieved its co-primary efficacy endpoints, as beloranib demonstrated a statistically significant reduction in both body weight and hyperphagia-related behaviors, making it the first investigational drug to demonstrate a positive impact on these two hallmark challenges in PWS.

Treatment with the 2.4 mg and the 1.8 mg doses of beloranib resulted in 9.45 percent and 8.20 percent reductions in body weight relative to placebo, respectively. Treatment with the 2.4 mg and the 1.8 mg doses of beloranib also resulted in reductions of hyperphagia-related behaviors of 7.0 units and 6.3 units relative to placebo, respectively, as measured by the Hyperphagia Questionnaire for Clinical Trials (HQ-CT).

Comment: In December 2015 Zafgen received notice from the FDA that its ZGN 433 (beloranib) investigational new drug application in patients with Prader-Willi syndrome (PWS) had been placed on complete clinical hold, affecting the ongoing open label extension (OLE) portion of the pivotal Phase III ZAF-311 bestPWS clinical trial. A complete clinical hold is an order that the FDA issues to a sponsor to suspend all clinical work requested under the Company’s IND application. This follows a second death reported during the trial. In order to address the clinical hold, Zafgen plans to present to the FDA the efficacy and safety data from the bestPWS ZAF-311 study, data from the Phase IIb trial of beloranib in severe obesity complicated by type 2 diabetes, ZAF-203, expected later this quarter, and a proposal for a risk mitigation strategy for beloranib in PWS.