Effectiveness of first-line immune checkpoint inhibitors (ICI) in advanced non-clear cell renal cell carcinoma (ccRCC).

316 Background: Immune checkpoint inhibitors (ICI) have demonstrated impressive activity in metastatic clear-cell renal cell carcinoma (ccRCC) and have become standard treatment options in this setting. Data supporting the effectiveness of ICI based therapy in non-clear cell RCC (nccRCC) is more limited. Methods: We performed a retrospective analysis using the International Metastatic RCC Database Consortium (IMDC). Patients with nccRCC were classified into 3 groups based on first-line therapy: ICI based therapy (in monotherapy or in combination), vascular endothelial growth factor targeted therapy (VEGF-TT) monotherapy, or mammalian target of rapamycin (mTOR) inhibitor monotherapy. Primary outcome was overall survival (OS). Secondary outcomes were time to treatment failure (TTF) and objective response rate (ORR). We used Kaplan-Meier method to compare OS and TTF between treatment groups and Cox proportional hazards models to adjust for prognostic covariates. Results: We identified 1181 patients with nccRCC. In first-line, 78.2% received VEGF-TT, 15.8% mTOR inhibitors, and 5.5% ICI based therapy, of which 41.5% in monotherapy, 30.8% doublet-ICIs and 27.7% an ICI combined with VEGF-TT. Median OS in the ICI group was 28.6 months, compared to 19.2 and 12.6 in the VEGF-TT and mTOR groups, respectively. Median TTF was 6.9 months vs. 5.1 and 3.9 and ORR was 25% vs. 17.8% and 5.8% in the ICI, VEGF-TT and mTOR groups, respectively. After adjusting for IMDC risk group, histological subtype, and age, the hazard ratio (HR) for OS was 0.58 (95% CI 0.35-0.94, p=0.03) for ICI vs. VEGF-TT and 0.48 (95% CI 0.29-0.80, p=0.005) for ICI vs. mTOR. Conclusions: In advanced nccRCC, first-line ICI based treatment appears to be associated with improved OS compared to VEGF and mTOR targeted therapy. These results need to be confirmed in prospective randomized trials. [Table: see text]