Outcomes With Combination Pembrolizumab and Axitinib in Second and Further Line Treatment of Metastatic Renal Cell Carcinoma

Immune checkpoint inhibitor-based combinations have an established role in the first-line treatment of patients with metastatic renal cell carcinoma; however, evidence on the selection of therapies in subsequent lines is limited. Herein, we present a retrospective analysis of patients who received pembrolizumab/axitinib beyond first line. In this heavily pretreated patient population, we observed an objective response in one-fourth of patients, with progression-free survival and response duration outcomes encouraging for further efforts examining this combination in prospective randomized settings. Introduction: Combination immune checkpoint inhibitors (ICI) and vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGF-R-TKI), including pembrolizumab/axitinib, are approved for first-line treatment of metastatic renal cell carcinoma (mRCC). Pembrolizumab/axitinib is associated with superior progression free survival (PFS), objective response rate (ORR), and overall survival over sunitinib. However, to date, the activit y and safet y of pembrolizumab/axitinib in later lines of therapy has not been reported. Materials and Methods: Clinical data of consec-utive patients receiving pembrolizumab/axitinib in the second-line or beyond for mRCC at Yale-New Haven Hospital were retrospectively collected. Best objective response was assessed using RECIST 1.1 criteria. Kaplan-Meier function was used to analyze survival. Results: Thirty-eight patients were included. Median age was 64, 92.1% had clear cell mRCC, 18.4% had sarcomatoid dedifferentiation; 94.7% had prior ICI and 39.5% had prior VEGF-R-TKI. Pembrolizumab/axitinib was administered as second-line therapy in 21 (55.5%) patients, third-line in 5 (13.2%) and beyond in 12 (30.2%). Adverse events (AEs) occurred in 86.8% of patients. Grade 3-4 AEs attributed to pembrolizumab and axitinib were seen in 18.4% and 6.4% of patients, respectively. No grade 5 AEs occurred. At a median follow up of 17.1 months, median PFS was 9.7 months (95% CI, 4.1-15.3). Amongst 36 response evaluable patients, the ORR was 25.0% (all partial) and disease control rate (including stable disease for at least 6 months) was 66.6%. The most frequent treatment sequence was first-line nivolumab/ipilimumab followed by second-line pembrolizumab/axitinib (n = 17, 44.7%); among this cohort, median PFS with pembrolizumab/axitinib was 11.1 (95% CI, 8.4-13.7) months, with an ORR of 31.4%. Conclusion: Combination pembrolizumab/axitinib among previously treated mRCC patients has activity, with AE rates comparable to those reported in the first line. Prospective studies evaluating ICI-VEGF-R-TKI combinations beyond first-line are warranted to identify the most beneficial treatment sequencing in mRCC.