Development of the investigational drug cabozantinib that initially showed promise in the treatment of metastatic, hormone-refractory prostate cancer has been halted due to discouraging results in a pivotal clinical trial. Enrollment in a second, phase III study of cabozantinib in prostate cancer has also been halted based on the negative outcome from the first study.
Prostate cancer is a hormonally sensitive disease that can be controlled for long periods with androgen deprivation therapy (ADT). When prostate cancer stops responding to this treatment is it referred to as hormone-refractory prostate cancer. Advances have been made in the treatment of hormone-refractory cancer, but challenges remain and new drugs like cabozantinib continue to be developed.
Cabozantinib is an investigational drug that targets two proteins—MET and VEGFR2—that play a role in the development and progression of many types of cancer. Initial results in a phase II clinical trial suggested that cabozantinib was active in the management of hormone refractory prostate cancer. However result form the so-called COMET-1 study that enrolled 960 men with advanced prostate cancer no longer responding to treatment with the chemotherapy drug docetaxel were not statistically significant and the study failed to achieve its primary endpoint causing the developer, Exelixis to discontinue the drugs development in prostate cancer.
Reference: Hussain M, Smith MR, Sweeney C et al. Cabozantinib (XL184) in metastatic castration-resistant prostate cancer (mCRPC): results from a phase II randomized discontinuation trial. Paper presented at: 2011 Annual Meeting of the American Society of Clinical Oncology; June 3-7, 2011; Chicago, IL. Abstract 4516.