This study reported on the real-world clinical outcomes of patients at seven academic institutions who were treated with enzalutamide, with the primary objective being to assess the effect of prior therapies (namely abireterone and docetaxel). Three hundred and ten patients received enzalutamide, with 79 of these having received abiraterone prior to this, 30 receiving prior docetaxel and 165 patients receiving both prior docetaxel and abiraterone. The groups that had received prior abiraterone achieved ≥30% prostate specific antigen (PSA) decline in 28% (solely abireterone) and 24% (abireterone and docetaxel) compared with 67% (no prior treatment) and 43% (purely docetaxel). Twelve-month overall survival was 64% (solely abiraterone) and 51% (abiraterone and docetaxel) compared with 78% (no prior treatment) and 77% (purely docetaxel). These findings demonstrate that in the abiraterone- and docetaxel-naïve patient, prior docetaxel attenuates the response to enzalutamide in terms of PSA decline and overall survival, while prior abiraterone attenuates this effect further. At a time when both abiraterone and enzalutamide have demonstrated such clinical promise, this study highlights the need to determine the optimal timing, sequence and combination of administration of these agents.
