CLINICAL STUDY OF SEQUENTIAL THERAPY WITH ABIRATERONE AND ENZALUTAMIDE FOLLOWING DOCETAXEL THERAPY FOR CASTRATION-RESISTANT PROSTATE CANCER

: (Purpose) This study is to evaluate the efficacy and safety of sequential therapy with two novel drugs, abiraterone and enzalutamide after docetaxel (DOC) therapy for castration-resistant prostate cancer (CRPC). (Material and methods) Twenty-one patients were identified received sequential therapy with abiraterone and enzalutamide after DOC therapy at our institution. We investigated PSA response (decrease of 50% or more) to prior administered drug as primary endpoint, and overall survival rate and occurrence of adverse events as secondary endpoint. (Results) There were 12 patients in the group preliminarily administered enzalutamide (Group E) and 9 patients in the group preliminarily administered abiraterone (Group A). The novel drugs were administered immediately following DOC therapy in nearly all cases. Of the 9 patients in Group A, only one patient (11%) and of the 12 patients in Group E, only one patient (9%) achieved PSA decrease of 50% or more, thus resulting in a poor response rate. There was not significantly difference in both groups. The overall survival rates of Group A and E were not significantly difference. There were three adverse events which required change drug. Those were two cases (appetite loss and general fatigue) on enzalutamide and one case (edema) on abiraterone. (Conclusion) This study suggested that sequential therapy with abiraterone and enzalutamide after DOC therapy had poor clinical benefit regardless of the order of administration of both drugs.