Cometriq fails to meet primary endpoint in metastatic castration-resistant prostate cancer

Results from a phase 3 trial have found that cabozantinib did not meet its primary endpoint of OS compared with prednisone for the treatment of metastatic castration-resistant prostate cancer, the manufacturer announced today.

In the phase 3 double-blind, placebo-controlled trial – COMET-1 – 960 patients with metastatic castration-resistant prostate cancer (mCRPC) whose disease progressed after treatment with docetaxel as well as abiraterone and/or enzalutamide were randomized 2:1 to receive either cabozantinib (Cometriq, Exelixis Inc.) (60 mg daily) or prednisone (5 mg twice daily).

According to study results, the median OS for the cabozantinib group was 11.0 months vs. 9.8 months for the prednisone group (HR 0.90; P=0.212).

In addition, median PFS was observed to be 5.5 months for the cabozantinib group vs. 2.8 months for the prednisone group (HR 0.50; P<.0001). Safety data were consistent with those observed in earlier-stage trials of cabozantinib in mCRPC.

“We are very disappointed that COMET-1 did not meet its primary endpoint of extending overall survival in men with mCRPC,” Michael M. Morrissey, PhD, president and CEO of Exelixis said in a press release. “We remain focused on the development program for cabozantinib beyond mCRPC, including the ongoing METEOR and CELESTIAL phase 3 pivotal trials, from which we expect top-line data in 2015 and 2017, respectively.”

Based on COMET-1 results, Exelixis has deprioritized the clinical development of cabozantinib in mCRPC and has halted enrollment in the COMET-2 trial, which is the second pivotal trial in mCRPC intended to evaluate pain palliation. Additionally, Exelixis-sponsored studies in mCRPC such as a randomized phase 2 study of cabozantinib in combination with abiraterone, have also been halted.