LAUSR

66 Background: Patients with mRCC with S/R components tend to have a poor prognosis with few therapeutic options available. Recent data suggest that immune checkpoint inhibitor (ICI)-based therapies may be especially effective for these patients. Our aim was to evaluate the efficacy of ICI-based therapies in patients with S/R mRCC. Methods: We retrospectively assessed objective response rate (ORR), progression free survival (PFS) & overall survival (OS) of patients with S/R mRCC treated at our institution with first-line ICI-based therapies and compared these to those of patients treated with first-line non-ICI-based therapies. Univariable and multivariable (adjusted for IMDC group) Cox and logistic regressions were performed. Results: 92 patients (70 S, 9 R, and 13 S&R) patients were included, of which 74 with a clear-cell component. For all patients (regardless of therapy), 74 (80.4%) patients experienced a PFS event (progression or death) and 52 (56.5%) died at 25.3 months (m) median follow-up. Overall median PFS was 5.3 m (95% CI= 3.4–7.2) and 24 m OS rate was 39.5% (27.4–51.7). Out of 78 patients in whom response was evaluable, ORR was 30.8% (20.4–41.2). Patients treated with ICI-based therapies had significantly better ORR, PFS, and OS on multivariable analysis (table). Conclusions: mRCC patients with S/R components have significantly better ORR, PFS, and OS with first-line ICI-based compared to non-ICI-based therapies. These data support the use of ICI-based therapies for patients with S/R mRCC. [Table: see text]