Enobosarm fails endpoints in Ph III study

US biotech firm GTx (Nasdaq: GTXI) revealed disappointing results for its two Phase III enobosarm clinical studies, the POWER trials, in patients with non-small cell lung cancer (NSCLC) receiving chemotherapy.

The news caused GTx shares to plunge 64% to $1.48 in morning trading on Monday, which, according to a Bloomberg report, was its biggest intra-day decline since the company’s initial public offering in 2004. Last year, the stock plummeted 30% after the US Food and Drug Administration put a clinical hold the company’s clinical trials evaluating Capesaris (GTx-758) for primary (first line) androgen deprivation therapy for advanced prostate cancer and secondary (second line) hormonal treatment (The Pharma Letter February 24, 2012).

The drug failed to meet the overall criteria for the co-primary responder endpoints of lean body mass and physical function as agreed on with the US FDA; the responder endpoints showed mixed results (for POWER1 and POWER2, p values at Day 84 for LBM were 0.036 and 0.113, respectively; p values at Day 84 for SCP were 0.315 and 0.289, respectively).