Updated analysis of progression-free survival with first subsequent therapy (PFS2) and safety in the SPARTAN study of apalutamide (APA) in patients (pts) with high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC).

144Background: In the phase 3 SPARTAN study, compared with placebo (PBO), APA, a next-generation androgen receptor inhibitor, decreased the risk of distant metastasis or death by 72% (hazard ratio [HR], 0.28; p < 0.0001) in men with high-risk nmCRPC. After 1 year of additional follow-up, PFS2 and safety were reevaluated to ensure maintenance of benefit against potential harm. Methods: Pts with nmCRPC and prostate-specific antigen doubling time of ≤ 10 mos were randomized 2:1 to APA (240 mg QD) + androgen deprivation therapy (ADT) or PBO + ADT. All pts who developed distant metastasis, determined by blinded independent central review, were eligible to receive subsequent therapy including open-label treatment with abiraterone acetate + prednisone, provided by the sponsor. The exploratory PFS2 end point (time from randomization to disease progression on subsequent anticancer therapy or death) was evaluated, as was incidence of treatment-emergent adverse events (TEAEs). Results: Median treatment duration with...