Response to first-line chemotherapy regimen is associated with efficacy of immune checkpoint blockade therapies in patients with metastatic urothelial carcinoma

Abstract

Background: atezolizumab (ATZ) has demonstrated antitumor activity in previous studies in patients with metastatic platinum-resistant urothelial carcinoma. However, the response rate of ATZ was modest. Therefore, finding biologic or clinical biomarkers that could help to select patients who respond to the immune checkpoint blockade remains important. Patients and methods: in this study, we present the retrospective analysis of 105 patients with urothelial cancer treated with ATZ after progression on first-line chemotherapy. Data of patients were obtained from patient files and hospital records. The association between response to first-line chemotherapy and ATZ was using Fisher's exact test. Median follow-up was calculated using the reverse Kaplan-Meier method. OS was estimated by using the Kaplan-Meier method. Results The median follow-up time was 23.5 months. Forty (74.1%) of patients who experienced clinical benefit after firs-line chemotherapy also had clinical benefit after atezolizumab, while only 14 (25.9%) of patients with initial PD after first-line chemotherapy subsequently experienced clinical benefit with ATZ (p = 0.001). The median OS on ATZ of 14.8 and 3.4 months for patients with clinical benefit and progressive disease in response to first-line chemotherapy, respectively (p = 0.001). Three of the adverse prognostic factors according to the Bellmunt criteria were independent factors of short survival: liver metastases {Hazard ratio [HR] = 1.9; p = 0.04}, ECOG PS >= 1 (HR = 2.7; p = 0.001), and Hemoglobin level below 10 mg/dl (HR = 2.8; p < 0.001). In addition, patients with clinical benefit from first-line chemotherapy (HR = 0.39; p < 0.001) maintained a significant association with OS in multivariate analysis. Conclusions: our study demonstrated that clinical benefit from first-line chemotherapy was independent prognostic factors on OS in patients' use of ATZ as second-line treatment in metastatic bladder cancer. Furthermore, these findings are important for stratification factors for future immunotherapy study design in patients with bladder cancer who have progressed after first-line chemotherapy.