Muscle-Wasting Drug Enobosarm Shows Mixed Results in Phase 3 Trials
Drug fails to meet responder endpoints in lung cancer patients (August 19)
Disappointing results have been reported from two phase 3 clinical studies of enobosarm (GTx, Inc.) — the POWER 1 and POWER 2 trials — in patients with non–small-cell lung cancer (NSCLC) receiving chemotherapy.
Both studies failed to meet the overall criteria for the co-primary responder endpoints of lean body mass (LBM) and physical function, as agreed upon with the FDA; the responder endpoints showed mixed results (for POWER 1 and POWER 2, P values at day 84 for LBM were 0.036 and 0.113, respectively; P values at day 84 for stair climb power [SCP] were 0.315 and 0.289, respectively).
An initial exploratory quantitative analysis demonstrated that enobosarm had a consistent effect on LBM compared with placebo in both studies at all assessment time points (P values were 0.0003 and 0.0227 at day 84 for POWER 1 and POWER 2, respectively). Corresponding analyses for SCP were inconsistent between trials (P values were 0.0336 and 0.7923, respectively).
In the POWER 1 trial, the four most common adverse events (in decreasing order of incidence) were nausea, alopecia, anemia, and vomiting. In POWER 2, the four most common adverse events reported were anemia, nausea, neutropenia, and vomiting. In the safety analysis of survival, there was no evidence of a difference between patients treated with enobosarm and placebo in either study.
Enobosarm is an investigational selective androgen receptor modulator (SARM).
Source: GTx, Inc.; August 19, 2013.