Disease Control with Prior Platinum-based Chemotherapy Is Prognostic for Survival in Patients with Metastatic Urothelial Cancer Treated with Atezolizumab in Real-world Practice

BACKGROUND: Atezolizumab, a programmed-death ligand-1 (PD-L1) inhibitor, is a novel treatment option for patients with metastatic urothelial cancer (mUC). Clinical prognostic factors, survival outcomes, and the safety of patients with mUC treated with atezolizumab, in a real-world setting, were investigated. PATIENTS AND METHODS: 62 patients with mUC, treated at the Institute of Oncology Ljubljana between May 8th 2018 and Dec 31st 2019, were included. Response rates and immune-related adverse events (irAE) were collected. Progression-free survival and overall survival times were assessed using the Kaplan-Meier method. The Cox proportional hazards model was applied to identify the factors affecting survival. RESULTS: Of 62 patients, five (8.1%) have not yet been evaluated and 20 (32%) died prior to the first radiographic evaluation. We observed clinical benefit in 19 (33%), objective response in 12 (21%), and complete response in five (9%) patients. Median overall survival for the whole population was 6.8 (95% CI, 2.6–11.0), for platinum-naïve 8.7 (95% CI: 0.8–16.5), and for the platinum-treated group 6.8 (95% CI, 3.7–10) months. At the 5.8 (0.3–23.1) month median follow-up, the median duration of the response was not reached. IrAE occurred in 20 (32%) patients and seven (11%) of them discontinued the treatment. Multivariate analysis in platinum-treated patients showed that a treatment-free interval of more than six months was prognostic for overall survival (OS). CONCLUSIONS: Responses to atezolizumab led to long disease remission in a subset of our patients. The median OS in our real-world population was compromised by a large percentage of patients with poor ECOG performance status (PS). A treatment-free interval from chemotherapy was associated with the longer survival of platinum-treated patients with mUC receiving further atezolizumab.