The Hsp90 inhibitor ganetespib stirred excitement at the 2013 ASCO Annual Meeting when results of the GALAXY-1 trial were presented, notes moderator Corey J. Langer, MD. In this study, ganetespib plus docetaxel demonstrated some promise as a treatment for patients with non-small cell lung cancer (NSCLC), in the second-line setting.

There was excitement for this class of agents, even before these results were presented, believes Anne S. Tsao, MD. Initially, the GALAXY-1 trial enrolled patients with all histologies. However, following the accrual of 72 patients with squamous NSCLC, the enrollment was halted. Overall, there was a high-rate of hemoptysis and a lack of efficacy in the squamous population, Tsao notes. After this point, only patients with adenocarcinoma were enrolled.

In the results presented at ASCO, the combination of ganetespib and docetaxel showed a nonstatistically significant improvement in overall survival and progression-free survival for patients with adenocarcinoma. However, Tsao suggests that several problems existed in the design of the trial. In total, patients in the ganetespib plus docetaxel arm received a median of 6 cycles of treatment compared to only 4 in the docetaxel alone arm. Moreover, patient characteristics were not well balanced in each arm, in regard to gender and location. Additionally, more patients received salvage pemetrexed in the investigational arm compared to the control, Tsao states.

A single biomarker of response was not identified in the phase II trial, notes Tsao. However, patients who received treatment greater than 6 months following diagnosis experienced a statistically significant prolongation in survival. As a result, a phase III trial was formed investigating ganetespib plus docetaxel for patients with adenocarcinoma after at least 6 months from the time of diagnosis, which is an unusual eligibility criterion for a clinical trial in NSCLC, Langer notes.