Pembrolizumab Retreatment in Patients with Advanced or Metastatic Urothelial Carcinoma Who Responded to First-course Pembrolizumab-based Therapy.

Patients with metastatic solid tumors who previously had stable disease or a response with immunotherapy may derive benefit from immunotherapy retreatment. This post hoc analysis evaluated pembrolizumab retreatment in patients with advanced/metastatic urothelial carcinoma who received pembrolizumab in KEYNOTE-045, KEYNOTE-052, or KEYNOTE-361, and either stopped pembrolizumab after a complete response (CR) or completed pembrolizumab (35 cycles [∼2 yr]) with an objective response or stable disease. Upon disease progression, protocol-specified pembrolizumab retreatment (200 mg intravenously every 3 wk) was administered for ≤17 cycles. Forty-nine patients met the criteria and were included. The median follow-up was 24.4 mo (range, 1.4-53.5). The median time between first-course therapy cessation and pembrolizumab retreatment was 10.7 mo (1.0-36.3). Twenty patients (41%) had an objective response with pembrolizumab retreatment, 65% of whom had a CR to first-course treatment. The median retreatment duration was 8.3 mo (range, 0.0-13.2); the median duration of response was 14.0 mo (2.1+ to 20.5). From retreatment initiation, the median (95% confidence interval) progression-free survival and overall survival were 9.5 mo (5.6-15.0) and 25.7 mo (21.5-27.5), respectively. Treatment-related adverse events occurred in 45% (grade 3-4: 6%; grade 5: 0%). Data suggest that pembrolizumab retreatment is beneficial and tolerable for some patients with advanced/metastatic urothelial carcinoma who previously had a CR or completed 2 yr of pembrolizumab.