Efficacy of Rotations Between Abiraterone Acetate and Apalutamide in mCRPC Patients

This is an open-label, randomized phase II study to investigate the feasibility of alternating cycles of treatment with abiraterone plus prednisone and apalutamide compared to sequential treatment of abiratereone plus prednisone followed by apalutamide. 7 centers in Greece will participate in the study. The study population consists of adult patients (over 18 years old) with histologically confirmed metastatic prostate adenocarcinoma who have disease progression - as defined by PCWG2 criteria - despite androgen deprivation therapy and who have not received prior therapy for their castration resistant disease. The purpose of the study is to determine the progression free survival, feasibility and safety profile of the experimental arm compared to standard of care. In the experimental arm alternating treatment will consist of repeating cycles of 24 weeks of treatment consisting of 12 weeks of abiraterone acetate 1000mg orally qd and prednisone 5mg orally bid, followed by 12 weeks of apalutamide 240 mg per day. There will be no wash out period between cycles. The comparative arm will be the standard regimen of abiraterone 1000mg orally qd plus prednisone 5mg orally bid until progression, followed thereafter by apalutamide 240mg orally qd until progression.