Introduction: Immune-related adverse events (irAEs) were mostly induced by immune checkpoint blockade (ICB) and were associated with the immune response. Whether irAEs are associated with clinical benefits during ICB treatment in cancer patients remains unclear. This systematic review and meta-analysis aimed to investigate the relationship between irAEs and clinical efficacy.

Methods: We systemically searched and selected irAEs and clinical outcome data from cancer patients treated with ICB in the PubMed, Embase, and Cochrane Central Trial databases up to July 26, 2018. Keywords used for the search included PD-1, PD-L1, CTLA-4, immune checkpoint and immune-related adverse events. The relationships between the occurrence of irAEs and the objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) were assessed using relative risk (RR) or hazard ratio (HR) values and 95% confidence intervals (CIs) in random-effect models.

Results: Nineteen eligible observational articles were included in this systematic review and fourteen studies including 3022 participants (1264 with irAEs and 1758 with non-irAE) were included in our meta-analysis. The occurrence of irAEs was significantly associated with higher ORR (RR = 2.36, 95% CI: 1.85-3.02; P < 0.001), better PFS (HR

= 0.48, 95% CI: 0.26-0.70; P < 0.001), and longer OS (HR = 0.42; 95% CI = 0.18-0.67; P = 0.001) than those in the non-irAE group. Subgroup analysis showed that the effect size of ORR in anti-PD-1 therapy (RR = 2.68, 95% CI, 2.21-3.26) was inferior to that of the anti-CTLA-4 therapy (RR = 1.91, 95% CI, 0.44-8.32). The meta-regression models also found that ICB type (anti-CTLA-4 or anti-PD-1) were associated with significant heterogeneity (P = 0.005).

Conclusion: In conclusion, irAEs indicate greater ORR, PFS and OS than non-irAEs in ICB treatment, and the relationship in anti-PD-1 therapy was stronger than in anti-CTLA-4 therapy. With appropriate management of irAEs, the clinical predictor, continued treatment may be possible to maximize its potential ICB benefits.

Note: This abstract was not presented at the meeting.

Citation Format: Xu Yang, Dongxu Wang, Jianzhen Lin, Jianping Xiong, Junyu Long, Yi Bai, Jin Bian, Hanchun Huang, Xiaobo Yang, Yilei Mao, Xinting Sang, Haitao Zhao. The occurrence of immune-related adverse events indicates better efficacy of immune checkpoint blockade in solid tumors: A systematic review and meta-analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4992.