KEYNOTE-365 cohort C updated results: Pembrolizumab (pembro) plus enzalutamide (enza) in abiraterone (abi)-pretreated patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC).
William L. Berry, Peter C.C. Fong, Josep M. Piulats, Leonard J. Appleman, Henry Jacob Conter, Susan Feyerabend, Neal D. Shore, Gwénaëlle Gravis, Brigitte Laguerre, Howard Gurney, Margitta Retz, Emanuela Romano, Loı̈c Mourey, Johann S. de Bono, Audrey E. Kam, Urban Emmenegger, Helen Wu, Charles Schloss, Christian Poehlein, Evan Y. Yu
Abstract
102 Background: KEYNOTE-365 (NCT02861573) is a phase 1b/2 study evaluating pembro in combination with other agents in mCRPC. An earlier report of cohort C showed activity and acceptable safety with pembro + enza. Updated results from cohort C are reported. Methods: Pts who failed or became intolerant to ≥4 wks of abi in prechemotherapy mCRPC state and whose disease progressed within 6 mo of screening per PSA progression or radiologic bone or soft tissue progression enrolled. Pts received pembro 200 mg IV Q3W with enza 160 mg/day PO. Primary end points: safety, PSA response rate (confirmed PSA decline ≥50%), and objective response rate (ORR) per blinded independent central review. Key secondary end points: disease control rate (DCR), duration of response (DOR), time to PSA progression, rPFS, and OS. Results: Of 102 treated pts, 73 discontinued, primarily due to progression (60%). Median age was 70 y (range, 43-87), 29% were PD-L1+, 17% had visceral disease, and 39% had measurable disease. Median follow up was 13 mo for all patients (n=102) and 17 mo for patients with ≥27 wks’ follow-up (n=69). See Table for efficacy outcomes. Treatment-related AEs occurred in 92 pts (90%); most frequent (≥20%) were fatigue (38%), nausea (22%), and rash (20%). Grade 3-5 treatment-related AEs occurred in 40 pts (39%). Three pts died of AEs (1 AE was treatment related [cause unknown]). Conclusions: With additional follow-up, pembro + enza continued to show activity in pts with abi-pretreated mCRPC. Safety of the combination was consistent with known profiles of pembro and enza. Clinical trial information: NCT02861573. [Table: see text]