The effects of enzalutamide and abiraterone on skeletal related events and bone radiological progression free survival in castration resistant prostate cancer patients: An indirect comparison of randomized controlled trials

Two new drugs, the CYP17 inhibitor abiraterone acetate and the androgen receptor (AR) antagonist enzalutamide, have recently shown to prolong OS prior chemotherapy or in docetaxel treated mCRPC patients, using steroidal therapy or placebo as control group. Updated analyses underlined the role of these new agents on two prostate-specific endpoints as radiographic progression-free survival (rPFS) and time to first skeletal-related event (tSRE). On the basis of these reports, we made an indirect comparison between abiraterone and enzalutamide. We obtained a clinically but not significant difference favouring enzalutamide over abiraterone in terms of rPFS (HR 0.48, 95% CI 0.22-1.02). No significant difference was shown in term of tSRE (HR 0.99, 95% CI 0.83-1.17). In conclusion, abiraterone and enzalutamide have both demonstrated to significantly delay the bone progression resulting in similar improvements in bone-related endpoints in patients with mCRPC.