Cabozantinib Not Superior to Prednisone for Pretreated mCRPC
When compared to prednisone, cabozantinib failed to improve overall survival of heavily pretreated patients with mCRPC.
When compared to prednisone, cabozantinib failed to improve overall survival of heavily pretreated patients with metastatic castration-resistant prostate cancer (mCRPC) who experienced disease progression after docetaxel and abiraterone acetate and/or enzalutamide, according to a study published in the Journal of Clinical Oncology.1
For this phase 3 COMET-1 study, investigators enrolled 1028 patients with progressive mCRPC after receipt of docetaxel and abiraterone and/or enzalutamide. Participants were randomly assigned 2:1 to receive cabozantinib 60 mg orally once daily or prednisone 5 mg orally twice daily.
Median overall survival was 11.0 months with cabozantinib, versus 9.8 months with prednisone (hazard ratio, 0.90; 95% CI, 0.76-1.06; P = .213), suggesting that the primary end point of overall survival was not met.
Researchers found, however, that 42% of patients who received cabozantinib achieved a bone scan response at week 12, versus 3% of those who had prednisone (P < .001). Radiographic progression-free survival favored cabozantinib (hazard ratio, 0.48; 95% CI, 0.40-0.57; P < .001).
Cabozantinib was associated with improvements in circulating tumor cell (CTC) conversion, bone biomarkers, and incidence of symptomatic skeletal events, but it was not associated with improved serum PSA outcomes.
Seventy-one percent of patients in the cabozantinib arm reported grade 3 to 4 adverse events, compared with 56% in the prednisone arm; 33% and 12% discontinued therapy, respectively.
1. Smith M, De Bono J, Sternberg C, et al. Phase III study of cabozantinib in previously treated metastatic castration-resistant prostate cancer: COMET-1. J Clin Oncol. 2016 Jul 11. doi: 10.1200/JCO.2015.65.5597 [Epub ahead of print]