SAUL, a single-arm study of atezolizumab for chemotherapy-pretreated locally advanced or metastatic carcinoma of the urinary tract: outcomes by key baseline factors, PD-L1 expression and prior platinum therapy

•Bellmunt stratification is an accepted risk algorithm in second-line chemotherapy for aUC.•The impact of pretreatment factors on immune checkpoint inhibition in aUC requires further evaluation.•We studied the prognostic significance of pretreatment factors in post-platinum immunotherapy of aUC in real-world setting.•Bellmunt factors, TFLC, prior therapy and PD-L1 expression were identified as prognostic factors.•Our results suggest a need for novel prognostic signatures for immunotherapy in aUC.