Geron slumps as imetelstat fails in Ph II breast cancer and NSCLC studies

Shares of US drug developer Geron Corp (Nasdaq: GERN) plunged 50% to $1.44 in pre-market trading yesterday, as the company revealed it is discontinuing its randomized Phase II trial of imetelstat in metastatic HER2-negative breast cancer because median progression-free survival (PFS) in the imetelstat arm was shorter than in the comparator arm.

The company also announced that it is continuing its randomized Phase II study of imetelstat in advanced non-small cell lung cancer (NSCLC). However, although a separate interim analysis of the NSCLC study suggested a modest trend of efficacy in favor of the imetelstat arm, the pre-specified success criteria in this trial are unlikely to be met, and, as a consequence, it is doubtful that Geron will take imetelstat forward into Phase III development for NSCLC.

The study in metastatic HER2-negative breast cancer was a randomized, controlled trial of 166 patients in which imetelstat was evaluated in combination with paclitaxel, compared to paclitaxel alone. The primary efficacy endpoint was an estimate of PFS.