Clinical outcomes and prognostic factors in metastatic nonclear cell renal cell carcinoma treated with immuno-oncology combination therapy

BACKGROUND: Metastatic nonclear cell renal cell carcinoma (nccRCC) is a heterogeneous disease with poor prognosis. The clinical characteristics and prognostic factors of immuno-oncology (IO) combination therapy for nccRCC are not well known. This study analyzed patients with metastatic nccRCC treated with IO combination therapy. METHODS: We retrospectively collected data from 447 patients with metastatic RCC treated with IO-based combination therapy as first-line treatment between September 2018 and July 2023 in a Japanese multicenter study. The primary endpoints were objective response rate, progression-free survival (PFS), and overall survival (OS), comparing groups treated with IO-IO and IO-tyrosine kinase inhibitor (TKI) therapies. RESULTS: Seventy-five patients with metastatic nccRCC were eligible for analysis: 39 were classified into the IO-IO group and 36 into the IO-TKI group. Median PFS was 5.4 months (95% CI: 1.6-9.1) for the IO-IO group and 5.6 (95% CI: 3.4-12.0) for the IO + TKI group. Median OS was 24.2 months (95% CI: 7.5-NA) for the IO-IO group and 23.4 (95% CI: 18.8-NA) for the IO + TKI group, with no significant difference. In univariate analysis, International Metastatic Renal Cell Carcinoma Database Consortium scores, Karnofsky performance status, neutrophil-to-lymphocyte ratio, and the presence of liver metastases were significantly associated with OS, whereas in multivariate analysis, only the presence of liver metastases was significantly associated with OS (P = .035). CONCLUSIONS: There was no significant difference in OS or PFS between IO-IO and IO-TKI combination therapy as first-line treatment for patients with nccRCC. Liver metastasis is a poor prognostic factor for such patients.