A phase II study of enzalutamide (Enz) with dutasteride (Dut) or finasteride (Fin) in men ≥ 65 years with hormone-naive systemic prostate cancer (HNSPCa).

179Background: Older men are at a high risk for adverse events (AEs) from androgen deprivation therapy (ADT). In prior studies, peripheral androgen blockade with bicalutamide and Fin was better tolerated but less efficacious than ADT in HNSPCa. The potential syngerism of Enz (a potent antiandrogen) and Dut/Fin (5-a reductase inhibitors for conversion of testosterone [T] to dihydrotestosterone [DHT]) provided the rationale for this Phase II study that examined the clinical efficacy and safety of Enz with Dut/Fin in men > 65 years with HNSPCa. Methods: Eligible patients were > 65 years (y) ; at a high risk of AE from ADT by comprehensive geriatric assessment or treating physicians; had metastatic (M1) or biochemical recurrent (M0) HNSPCa with a PSA doubling time 50ng/dl. They received Enz (160mg daily) and Dut (0.5mg daily) or Fin (5mg daily) until disease progression according to the Prostate Cancer Working Group 2 guidelines. The primary study endpoint is time to PSA progression. T...