Efficacy and safety of immunological checkpoint inhibitors combined with anti-angiogenic drugs in first-line treatment of metastatic renal cell carcinoma: a systematic review and meta-analysis

Background: Immune checkpoint inhibitors (ICIs) have shown promising results for the second-line treatment of metastatic renal cell carcinoma (mRCC). Several randomized controlled trials have so far also evaluated the efficacy of ICIs for first-line treatment of mRCC. In this study, we conducted a meta-analysis of relevant studies to further clarify the efficacy and safety of ICIs combined with anti-angiogenic drugs for the treatment of mRCC. Methods: We searched the PubMed, Embase, and Cochrane libraries for RCT trials of ICIs combined with anti-angiogenic drugs for first-line treatment of mRCC published before November 20, 2019. A meta-analysis was conducted based on methodological recommendations by the Cochrane Collaboration. Results: Four articles with a total of 2,967 patients met the inclusion criteria. Our meta-analysis revealed that progression-free survival (PFS) and objective response rate (ORR) were significantly improved in the experimental group while there was no significant difference in overall survival (OS) (HR 0.75, 95% CI: 0.67-0.84; HR 1.43, 95% CI: 1.07-1.91; HR 0.74, 95% CI: 0.53-1.03). After stratification for PD-L1 expression, OS, PFS, and ORR of PD-L1 positive patients were significantly increased in the experimental group (HR 0.74, 95% CI: 0.56-0.96; HR 1.66, 95% CI: 1.11-2.49; HR 0.65, 95% CI: 0.57-0.75). Conclusions: Immunological checkpoint inhibitors combined with anti-angiogenic drugs as a first-line treatment for mRCC improve PFS and ORR. This effect is more pronounced in PD-L1 positive patients, where ICIs also improve OS. ICIs do not increase the incidence of adverse events.