Nivolumab in previously treated metastatic renal cell carcinoma: real-world data from the Czech Republic and Slovakia.

Background: Immune checkpoint inhibitors (ICIs) have become a cornerstone of treatment for metastatic renal cell carcinoma (mRCC). Nivolumab monotherapy remains an established option in previously treated patients; however, real-world data (RWD) from Central and Eastern Europe are limited. Methods: We conducted a retrospective multicenter cohort study using data from the RENIS II registry, including 501 patients with mRCC treated with nivolumab in the second or later line between 2013 and 2025 across the Czech Republic and Slovakia. The primary endpoints were overall survival (OS) and progression-free survival (PFS). Secondary endpoints included objective response rate (ORR), disease control rate (DCR), safety, and exploratory analyses of baseline inflammatory indices (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], and systemic immune-inflammation index [SII]). Results: Median OS was 24.2 months and median PFS was 8.6 months. The ORR was 28.8% and the DCR was 61.2% in the response-evaluable population. Grade 3/4 adverse events were recorded in 11.4% of patients. In exploratory analyses, higher baseline NLR, PLR, and SII were associated with inferior survival in univariable analyses. In multivariable models, NLR and PLR remained independently associated with OS and PFS, whereas SII did not retain independent prognostic significance. Conclusion: In this large multicenter real-world cohort, nivolumab monotherapy demonstrated consistent clinical activity and manageable toxicity in previously treated mRCC, with outcomes comparable to those reported in clinical trials and other European real-world studies. Baseline inflammatory indices, particularly NLR and PLR, showed potential prognostic value and warrant further investigation.