Salvage nivolumab and ipilimumab after prior anti‐PD‐1/PD‐L1 therapy in metastatic renal cell carcinoma: A meta‐analysis

BACKGROUND: Salvage nivolumab and ipilimumab after prior anti‐PD‐1/PD‐L1 therapy is frequently used off‐label for clear cell metastatic renal cell carcinoma (mRCC). However, limited data are available to guide such therapy. We performed a meta‐analysis to characterize further the safety and efficacy of salvage nivolumab and ipilimumab. METHODS: We conducted a systematic review in accordance with PRISMA. Studies of salvage nivolumab and ipilimumab in patients with mRCC published in English before June 1, 2021 were included. We also included patients treated at the Ohio State University from 2012 to 2020 through a retrospective chart review. The included studies were further stratified into adaptive and standard groups based on their designs. We calculated objective response rate (ORR) and adverse events (AEs) via pooled data and quantitative synthesis using the Stata metaprop procedure. A conservative random effect model was used to combine values. RESULTS: A total of 7 studies and 310 patients were included. Salvage nivolumab and ipilimumab had an ORR of 14% (95% CI, 0.09–0.21) and median progression‐free survival ranged between 3.7 and 5.5 months. Four out of the seven studies were standard design, whereas the other three studies were adaptive. The ORR was numerically higher in the standard group compared with the adaptive group (21% and 9–10%, respectively). The responses to salvage nivolumab and ipilimumab did not correlate with the initial anti‐PD‐1/PD‐L1 responses (odds ratio = 1.45; p = 0.5). Grade ≥3 AEs occurred in 26% of the patients (95% CI, 0.19–0.33). There were no new safety signals observed in this study. CONCLUSION: Salvage nivolumab and ipilimumab demonstrated moderate antitumor activity and a manageable safety profile in patients with mRCC who had prior anti‐PD‐1/PD‐L1 therapy. IMPLICATION FOR PRACTICE: Patients with metastatic renal cell carcinoma have limited treatment options after progressive disease on anti‐PD‐1/PD‐L1 therapy. The role of salvage nivolumab and ipilimumab in this patient population is poorly defined. The studies on this highly important and clinically relevant topic are limited by small sample sizes. The results from our meta‐analysis suggest that nivolumab and ipilimumab are feasible in the salvage setting with moderate efficacy and acceptable toxicity profile. The response rates differ with different treatment designs. This information will be beneficial to guide clinical decision‐making and accurately estimating toxicity.