Re‐challenging chemotherapy after pembrolizumab in platinum‐refractory urothelial carcinoma

Objectives To assess the real‐world clinical benefit of re‐challenging chemotherapy after pembrolizumab in patients with metastatic urothelial carcinoma (mUC), as there have been several reports suggesting that programmed cell death protein‐1/programmed death‐ligand 1inhibitors can restore platinum sensitivity. Patients and Methods Of 236 patients treated with pembrolizumab, we excluded 45 patients who did not experience progressive disease (PD) for pembrolizumab during the follow‐up and 86 patients who discontinued pembrolizumab by the diagnosis of PD followed by the best supportive care. A total of 105 patients were identified for a logistic regression propensity score model to compare the survival outcomes between patients treated with continuing pembrolizumab (80) and re‐challenging chemotherapy (25) after the diagnosis of PD for pembrolizumab. Results A median overall survival (OS) from PD for pembrolizumab was 11 months in 105 patients. Of 25 patients treated with re‐challenging chemotherapy, platinum‐including chemotherapy (gemcitabine and cisplatin; gemcitabine/cisplatin/paclitaxel [GCP]; methotrexate and vinblastine and adriamycin and cisplatin; and methotrexate and carboplatin and vinblastine MCAVI) was offered in 20 patients (80%). The objective response rate (ORR) for the first‐line chemotherapy in the 105 patients was 30%, with a comparable ORR in 25 patients treated with re‐challenging chemotherapy of 28%. GCP as a re‐challenging regimen was offered in 12 of 25 (48%) patients. The ORR for the GCP regimen was 50%. Propensity score matching was performed using putative clinical factors, from which 34 patients were identified as pair‐matched groups. The OS for patients treated with re‐challenging chemotherapy was significantly longer than continuing pembrolizumab (a median of 13.9 and 5.8 months, respectively: P = 0.048). Conclusion Re‐challenging chemotherapy including platinum agents after PD with pembrolizumab offers clinical benefits in patients with mUC.