Sensitivity analyses for progression-free survival (PFS) and radiographic PFS (rPFS) from the phase II STRIVE trial comparing enzalutamide (ENZA) with bicalutamide (BIC) in men with castration-resistant prostate cancer (CRPC).
Penson, DF; Armstrong, AJ; Concepcion, RS; Wu, K; Wang, F; Krivoshik, AP; Phung, D; Higano, CS
Published in: Journal of Clinical Oncology
169 Background: STRIVE was arandomized, double-blind, phase 2 trial comparing ENZA vs BIC in nonmetastatic (M0) or metastatic (M1) CRPC. In this study, ENZA significantly reduced the risk of prostate cancer progression or death compared with BIC in patients with M0 or M1 CRPC. Methods: 396 men with M0 (n = 139) or M1 (n = 257) CRPC were randomized to ENZA 160 mg/day or BIC 50 mg/day. The primary endpoint of PFS was defined as the time from randomization to radiographic progression, PSA progression, or death from any cause, whichever occurred first. rPFS was defined as the time from randomization to death or the first objective evidence of radiographic disease progression in soft-tissue disease per RECIST v1.1 or in bone per PCWG2 guidelines. Sensitivity analyses were prespecified to assess the impact of alternative definitions for PFS in all patients and were performed post hoc for the key secondary endpoint of rPFS in patients with M1 disease only (table). Results: Consistent with the primary analyses of PFS and rPFS, the results from all sensitivity analyses favored ENZA over BIC (table). Conclusions: PFS and rPFS sensitivity analyses in STRIVE demonstrated a consistent and robust treatment benefit with ENZA compared with BIC by any variation of the original definition of PFS. Clinical trial information: NCT01664923. [Table: see text]