Atezolizumab in Patients with Pretreated Urothelial Cancer: a Korean Single-Center, Retrospective Study

PURPOSE: Treatment targeting immune checkpoint with programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors has demonstrated efficacy and tolerability in the treatment of metastatic urothelial carcinoma (mUC). We investigated the efficacy and safety of atezolizumab in mUC patients who failed platinum-based chemotherapy. Materials and Methods: A retrospective study using the Samsung Medical Center cancer chemotherapy registry was performed on 50 consecutive patients with mUC treated with atezolizumab, regardless of their PD-L1(SP142) status, as salvage therapy after chemotherapy failure between May 2017 and June 2018. Endpoints included overall response rate (RR), progression-free survival (PFS), and safety. RESULTS: Among 50 patients, men constituted 76% and the median age was 68 years (range, 46 to 82 years). Twenty-three patients (46%) received atezolizumab as second-line therapy. PD-L1 (SP142) status IC0/1 and IC2/3 were found in 21 (42%) and 21 (42%) of patients, respectively; in eight patients (16%), PD-L1 (SP142) expression was not available. Atezolizumab was generally well tolerated, with pruritus and fatigue being the most commonly observed toxicities. As a result, partial response was noted in 20 patients (40%), with 12 (24%) stable diseases. RRwas higherin IC2/3 (62%) than in IC0/1 patients (24%, p=0.013). The median PFS was 7.4 months (95% confidence interval, 3.4 to 11.4 months). As expected, PFS also was significantly longer in IC2/3 patients than in IC0/1 (median, 12.7 vs. 2.1 months; p=0.005). PFS was not significantly influenced by age, sex, performance status, number of previous chemotherapy, site of metastases, or any of the baseline laboratory parameters. CONCLUSION: In this retrospective study, atezolizumab demonstrated clinically efficacy and tolerability in unselected mUC patients who failed platinum-based chemotherapy.