Real-world treatment outcomes of first-line axitinib plus pembrolizumab in patients with advanced renal cell carcinoma in the United States.

314 Background: The combination of axitinib plus pembrolizumab (AXI+PEM) is a standard of care in the first-line (1L) treatment of patients with advanced clear cell renal cell carcinoma (RCC). This analysis describes the demographic and clinical characteristics, treatment and outcomes of patients receiving 1L AXI+PEM in a real-world setting. Methods: Medical record data were extracted from the Flatiron Health Database, which includes ̃280 cancer clinics across 800 sites in the US. Patients had confirmed Stage IV or metastatic RCC and initiated 1L AXI+PEM on or after 1/1/2018 to 3/31/2021. Tumor response is reported as best overall response to 1L therapy; real-world progression-free survival (rwPFS) and overall survival (rwOS) are reported as patients without a clinical event (rwPFS; progression/death; rwOS; death) at landmark time periods (3, 6, 9, and 12 months); denominators include censored patients. Other data are reported as medians (min, max) unless otherwise noted. Results: Three hundred and fifty-five patients received 1L AXI+PEM, with follow-up of 9.7 (0.1–24.3) months. Most patients were male (69.6%), and age was 68.0 (21.0–84.0) years. At diagnosis, 55.5% of patients had Stage IV RCC and 77.2% of patients had clear cell histology. IMDC Risk Score was favorable, intermediate, and poor in 27 (7.6%), 126 (35.5%), and 76 (24.4%) patients, respectively. At the time of analysis, 270 patients (76.1%) received only 1L therapy with AXI+PEM, while 85 patients (24.3%) received ≥1 subsequent line of treatment. VEGF-R inhibitors were the most commonly used second-line (2L) treatment (51 patients, 60.0%), with cabozantinib as the most frequently used VEGF-R inhibitor (40 patients, 47.1%). rwPFS at 3 months and 1 year was achieved by 248 patients (69.9%) and 77 patients (21.7%), respectively. rwOS ranged from 293 patients (82.5%) surviving at 3 months to 142 patients (40.0%) surviving at 1 year. Best overall response rate to 1L was 47.9% (complete or partial response observed in 170/355 patients). Conclusions: This study provides real-world evidence for the use and effectiveness of 1L AXI+PEM in patients with advanced RCC. AXI+PEM was used across all IMDC risk groups. While these initial finding support the use of AXI+PEM, additional follow-up is warranted to provide further understanding of the clinical outcomes and treatment patterns of patients with advanced RCC in the US receiving 1L AXI+PEM.