Oncological Outcomes and Prognostic Factors of Platinum‐Based Chemotherapy Followed by Avelumab Maintenance Therapy Compared With Platinum‐Based Chemotherapy Alone: A Propensity Score–Matched Analysis in a Real‐World Population

OBJECTIVES: Avelumab maintenance therapy following platinum-based chemotherapy is recommended as an alternative treatment in patients with locally advanced or metastatic urothelial carcinoma; however, real-world data are limited, and no predictive system has been established to identify suitable candidates for avelumab at the initiation of chemotherapy. METHODS: This retrospective study analyzed 324 patients with locally advanced or metastatic urothelial carcinoma who received platinum-based chemotherapy. Patients were divided into three groups: 130 who received avelumab (avelumab group), 58 who did not experience disease progression on chemotherapy within 4 cycles but did not receive avelumab (PBC-only group), and 136 who experienced disease progression on chemotherapy within 4 cycles (PBC-PD group). Oncological outcomes were compared among the groups, and a system for predicting the maintained response to chemotherapy for 4 or more cycles was explored. RESULTS: The avelumab group had significantly longer overall survival than the other two groups. After propensity score matching, overall survival was significantly longer in the avelumab group than in the PBC-only group. Lymph node-only metastasis and a low neutrophil-to-lymphocyte ratio were identified as predictive factors for maintaining response to chemotherapy. Among patients with these two factors (favorable group), 81.1% maintained a response, and those who received avelumab maintenance therapy showed that the median overall survival was 33.4 months from initiation of chemotherapy. CONCLUSIONS: The survival benefit of avelumab following chemotherapy compared to chemotherapy alone was confirmed. In the favorable group, avelumab following chemotherapy may be a valuable option if they are ineligible or unwilling to receive the preferred regimen.