Treatment-free Survival After First-line Therapies for Metastatic Renal Cell Carcinoma: An International Metastatic Renal Cell Carcinoma Database Consortium Analysis

BACKGROUND AND OBJECTIVE: Patients receiving immune checkpoint blockade (ICB) therapy may experience periods of prolonged disease control without a need for systemic therapy. Treatment-free survival (TFS) is an important measure for this period, but no data are available for patients with metastatic renal cell carcinoma (mRCC) starting first-line agents. Our aim was to analyze TFS outcomes for patients with mRCC starting first-line therapy. METHODS: We analyzed data for patients with mRCC starting first-line systemic therapy with VEGFR-targeted monotherapy, an ICB + VEGFR combination, or an ICB doublet from February 1, 2014 to February 1, 2023 from the multicenter International Metastatic RCC Database Consortium (IMDC) database. We estimated 36-mo TFS as the difference in restricted mean survival time between (1) the time to first-line therapy discontinuation and (2) the time to subsequent systemic therapy initiation. KEY FINDINGS AND LIMITATIONS: The study population included 3758 patients receiving either first-line VEGFR monotherapy (n = 2635), an ICB + VEGFR combination (n = 354), or doublet ICB (n = 769) were included. For the IMDC favorable-risk cohort, the 36-mo TFS estimate was 3.1 mo (95% confidence interval [CI] 1.5-4.6) for the VEGFR monotherapy group and 3.7 mo (95% CI 0.2-7.2) for the ICB + VEGFR group. For the IMDC intermediate-/poor-risk cohort, TFS was 2.1 mo (95% CI 1.4-2.8) for the VEGFR monotherapy group, 3.7 mo (95% CI 1.0-6.4) for the ICB + VEGFR group, and 5.3 mo (95% CI 3.8-6.8) for ICB doublet group. Limitations include the retrospective design and an inability to quantify time spent with adverse events. CONCLUSIONS AND CLINICAL IMPLICATIONS: Our study demonstrates that patients with IMDC intermediate or poor risk treated with ICB doublet therapy experienced longer TFS than those treated with VEGFR monotherapy in the first-line setting. These results emphasize the utility of TFS as an informative endpoint and provide survival estimates to inform decision-making in mRCC. PATIENT SUMMARY: For patients with metastatic kidney cancer, we compared the survival time free from a second treatment line for different first-line treatment options. The results show that the time free from second-line treatment was longer when first-line treatment was with a combination of two immunotherapy drugs (ipilimumab and nivolumab) in comparison to other treatment options.