Background and importance Few options exist for patients with metastatic urothelial carcinoma (MUC). Atezolizumab, an anti-PD-L1 immune checkpoint inhibitor, has been shown to reduce tumour size in patients who have been treated with platinum chemotherapy or who are not eligible for such treatment in MUC.

Aim and objectives To evaluate the effectiveness and safety of atezolizumab in MUC in real clinical practice, comparing the results with the pivotal clinical trial IMvigor211.

Material and methods This was a retrospective observational study including all patients with MUC treated with atezolizumab, between January 2018 and October 2021. Variables included were age, sex, smoking status, Eastern Cooperative Oncology Group (ECOG), line of treatment, cycles received, duration and causes of treatment discontinuation (progression, toxicity, death). Effectiveness was assessed by the Kaplan–Meier method (SPSS v25.0) in terms of progression-free survival (PFS) and overall survival (OS). Adverse effects (AE) were collected and classified according to the Common Terminology Criteria for Adverse Events (CTCAE) scale v5.0.

Results 33 patients (87.9% men) were included. Median age was 67 (53–85) years. 24.2% were smokers and 66.7% former smokers. All patients had ECOG ≤1 at the begining of treatment. Treatment line of atezolizumab: 12.1% firstline, 72.7% secondline, 12.1% thirdline and 3% fourthline. 87.9% received at least one previous platinum-based line. Median of cycles received and duration of treatment were 5 (1–21) and 4 months, respectively. 81.8% of the patients discontinued therapy: 21.2% due to death and 60.6% due to progression. Median PFS and OS were 5 months (95% CI 3.9 to 6.1) and 15 months (95% CI 1.7 to 28.3), respectively. In IMvigor211, median PFS and OS were 2.1 and 8.6 months, respectively. 39.4% of patients had AE only grade 1–2. The most comon AE were pruritus (n=6), asthenia (n=3), oedema (n=3), constipation (n=2) and neuropathy (n=2). In IMvigor211, 95% had AE (55.8% ≥ grade 3) and the most common of any grade were fatigue, pruritus and asthenia.

Conclusion and relevance The effectiveness results observed in real clinical practice appear to be superior to those obtained in the pivotal study, although our sample size and design are limited. The safety profile appears to be better than IMvigor211 with a similar toxicity profile.

Conflict of interest No conflict of interest