Real-world outcomes in patients with metastatic clear cell renal cell carcinoma receiving front-line axitinib plus pembrolizumab versus ipilimumab plus nivolumab.

4551 Background: Front-line treatment for patients (pts) with metastatic clear cell renal cell carcinoma (mRCC) has undergone rapid advances in the last five years. This evolution has led to uncertainty about the optimal first line combination regimen. Herein, we compare real-world outcomes in pts treated with either axitinib/pembrolizumab (A/P) or ipilimumab/nivolumab (I/N) reported by International Metastatic RCC Database Consortium (IMDC) score. Methods: The nationwide Flatiron Health electronic health records-derived database was used to select pts diagnosed with mRCC and treated with front-line A/P or I/N from 2018-2020. The primary endpoints were overall-survival (OS) and real-world progression free survival (rwPFS). The survival analyses were adjusted using propensity score-based Inverse Probability of Treatment weighting, providing balance on age, gender, insurance, race, IMDC, practice type, and nephrectomy. Survival was assessed from beginning of therapy, and survival by treatment groups was compared using weighted and unweighted Kaplan-Meier curves with log-rank tests and weighted Cox proportional hazards regressions. Disease characteristics between the treatment groups were compared using chi-square and T-tests. Results: 821 pts received frontline A/P (n=259) or I/N (n= 562). Demographics and clinical parameters were similar between the two cohorts. Median age was 66 years, 73% were male, and 54.9% had a nephrectomy. 459 pts had all IMDC criteria factors available, 242 pts had missing factors but enough to define as intermediate/poor risk, 120 pts had unknown IMDC risk. Adjusted median OS was not statistically different: mOS for A/P was not reached (NR) while I/N was 22 mo (95% CI, 19.8-NR; p=0.40). Twelve-month survival was 68.5% for A/P treated pts and 65.8% for I/N treated pts (P=0.41). Twelve-month rwPFS was 41.4% for A/P treated pts and 39.7% for I/N treated pts (P=0.14). No statistical difference in survival was seen within IMDC risk strata (see table). Conclusions: In this retrospective, real-world study of pts treated with front-line A/P or I/N, 12-month survival was not statistically different irrespective of IMDC risk. Longer follow-up will be necessary to discern any significant differences.[Table: see text]