Clinical activity of PD1/PDL1 inhibitors in metastatic non-clear cell renal cell carcinoma (nccRCC).
482 Background: PD1/PDL1 inhibitors have shown significant activity in the treatment of patients (pts) with metastatic clear cell renal cell carcinoma (ccRCC), but their activity in nccRCC is poorly characterized. Methods: We conducted a retrospective multicenter study of pts with metastatic nccRCC treated with PD1/PDL1 inhibitors. Baseline clinical parameters, overall response rate (ORR) by RECIST, time-to-treatment failure (TTF), and overall survival (OS) were summarized. Results: We identified 40 pts across 8 academic institutions. Fourteen (35%) had papillary histology, 10 (25%) chromophobe, 3 (8%) translocation, and 7 (18%) unclassified. Six (16%) had ccRCC with a sarcomatoid component > 30%. 20% had International Metastatic RCC Database Consortium (IMDC) favorable-risk disease, 60% intermediate, and 20% poor-risk. Ten (25%) were treatment-naïve and the majority received PD1/PDL1 monotherapy (n=30, 75%), while the remaining received a combination of PD1/PDL1 with anti-VEGF(R) or anti-CTLA4 therapy. ORR for the total cohort was 18% and 10% for PD1/PDL1 monotherapy pts (Table). With a median follow-up of 5.6 months, the overall median TTF was 4.7 months (2.9-15.9) and six-month OS was 81% (60-91%). Conclusions: PD1/PDL1 blockade resulted in some activity in pts with various nccRCC histologies. In the absence of available clinical trials, this data may support the use of PD1/PDL1 blocking agents in pts with nccRCC. [Table: see text]