The pharmaceutical company Exelixis has announced that their experimental treatment, cabozantinib has failed the Phase III clinical trial for men with metastatic castration-resistant prostate cancer (mCRPC). In the trial the experimental treatment cabozantinib was compared to the drug prednisone.

In the trial known as COMET-1, Cabozantinib, a tyrosine kinase inhibitor, did not meet its primary endpoint of demonstrating a statistically significant increase in overall survival (OS) for men compared to prednisone.   The trial compared the effectiveness of cabozantinib and prednisone in 960 men with mCRPC whose disease progressed after treatment with docetaxel as well as abiraterone and/or enzalutamide.

Men were randomized 2:1 to receive cabozantinib (60 mg daily) or prednisone (5 mg twice daily). COMET-1 yielded a median overall survival (OS) for men treated with cabozantinib of 11 months, compared with 9.8 months for the prednisone arm, which was not statically significant. Median progression-free survival (PFS) was 5.5 months for the cabozantinib arm.

Joel T. Nowak, M.A., M.S.W.