Pembrolizumab in Combination With Gemcitabine and Concurrent Hypofractionated Radiation Therapy as Bladder-sparing Treatment for Muscle-invasive Urothelial Cancer of the Bladder: A Multicenter Phase 2 Trial.

Abstract

Trimodality therapy (TMT) is an accepted bladder-preserving option for selected patients with muscle-invasive bladder cancer (MIBC). Pembrolizumab has demonstrated activity in MIBC and may enhance the effects of chemotherapy and radiation. We evaluated the safety and efficacy of adding pembrolizumab to TMT. In this multicenter phase 2 trial, patients with MIBC received one dose of pembrolizumab followed by maximal transurethral resection, then definitive bladder radiation with concurrent low-dose gemcitabine and pembrolizumab every 3 wk for three doses. The primary end point was 2-yr bladder-intact disease-free survival (BIDFS). Secondary end points included safety, metastasis-free survival (MFS), and overall survival (OS). Fifty-four patients were enrolled, including 48 in the efficacy cohort; 67% had clinical stage T2 disease. The 2-yr BIDFS was 60% (95% confidence interval [CI], 45-73). Two-yr MFS and OS were 81% (95% CI, 66-92) and 83% (95% CI, 69-91), respectively. Grade ≥3 treatment-related adverse events occurred in 25% of patients. Limitations include the single-arm design and modest sample size. Pembrolizumab combined with gemcitabine-based chemoradiation was feasible and showed efficacy comparable to standard TMT. Ongoing phase 3 trials will further define its role in bladder preservation.