Exelixis' cabozantinib fails to meet primary endpoint in Phase III prostate cancer trial

US biotech firm Exelixis (Nasdaq: EXEL) has announced top-line results from the final analysis of COMET-2, a randomized, double-blind, controlled trial of cabozantinib, that did not reach its primary endpoint in men with metastatic castration-resistant prostate cancer (mCRPC).

The trial was in for men who are suffering from moderate to severe pain despite optimized narcotic medication, and whose disease has progressed following treatment with docetaxel as well as abiraterone and/or enzalutamide.

It did not meet its primary endpoint of alleviation of bone pain, as determined by comparing the percentage of patients in the two treatment arms who achieved a pain response at week six that was confirmed at week 12 without increase in narcotic medication. Some 15% of patients in the cabozantinib arm reported a pain response, compared to 17% of patients in the control arm receiving mitoxantrone/ prednisone. The difference in pain response between the arms was not statistically significant. The safety profile of cabozantinib in the trial was consistent with that observed in previous studies in mCRPC.