4583 Background: The use of High-Dose Corticosteroids (HDC) has been linked to poor outcomes in patients with lung cancer treated with immune checkpoint inhibitors (ICIs) (Ricciuti B, JCO, 2019). There is no data on the effect of HDC on renal cell carcinoma patients (RCC) treated with immunotherapy. We hypothesized that HDC use would be associated with worse outcomes in RCC patients receiving ICIs. Methods: This study evaluated a retrospective cohort of patients with RCC at Dana-Farber Cancer Institute in Boston, MA. Clinical information including demographics, IMDC risk score, RCC histology, steroid administration, ICI regimen, line of therapy, time to treatment failure (TTF) and overall survival (OS) were collected. Patients were divided into those receiving HDC (prednisone ≥10 mg or equivalent for ≥ 1 week, HDC group) or not receiving HDC (No-HDC group). HDC administration was evaluated in relation to TTF and OS in a univariate analysis (Log-rank test) and a multivariate analysis (Cox regression). Results: 190 patients with RCC receiving ICIs were included, with a median age of 59 years. HDC were administered to 56 patients and 134 patients received no (N= 116) or only low-dose (N=18) steroids. In the HDC group, 40 patients received steroids for immune-related adverse events, 8 for other cancer-related indications, and 8 for non-oncological indications. There was no difference in TTF between the HDC and No-HDC groups (12-mo TTF rate: 34.8 vs. 32.3%, respectively; log-rank p=0.65). Similarly, there was no difference in OS between the HDC and No-HDC groups (36-mo OS rate: 56.7 vs. 62.4%, respectively; log-rank p=0.97). After adjusting for IMDC risk group, RCC histology, ICI regimen type, and line of therapy, TTF and OS did not differ in the HDC group as compared to No-HDC group (HR=1.14 [95%CI: 0.80-1.62], p=0.44 and HR=1.17 [95%CI: 0.65-2.11], p=0.59, respectively). Conclusions: In this retrospective study of patients with RCC treated with ICIs, administration of high-dose corticosteroids was not associated with worse outcomes.[Table: see text]