The association between immune-related adverse events and the prognosis of solid cancer patients treated with immunotherapy: a systematic review and meta-analysis

BACKGROUND: Immune-related adverse events (irAEs) are common during immune checkpoint inhibitor (ICI) treatment and reported to be associated with good survival. This study evaluated the association between onset timing of irAEs and survival of cancer patients treated with ICIs. METHODS: Databases including PubMed, Embase, and the Cochrane library were systematically searched to retrieve clinical studies assessing the relationship between irAEs and survival in cancer patients with ICIs. The overall response rate for treatment response and hazard ratio (HR) for overall survival (OS) and progression-free survival (PFS) were calculated using RevMan 5.3. Subgroup analysis in terms of cancer type, ICIs type, region, specific irAEs, accordingly. RESULTS: A total of 34 studies were included. The HRs for OS and PFS in cancer patients with versus without irAEs were 0.57 [95% confidence interval (CI): 0.44, 0.74; p < 0.0001], and 0.50 (95% CI: 0.37, 0.67; p < 0.00001), respectively. The odds ratio for overall response in cancer patients with irAEs was 4.72 (95% CI: 3.48, 6.40; p < 0.00001) compared with those without irAEs. Subgroup analyses suggested that the prognostic role of irAEs was associated with cancer types and region, but not irAEs types. The landmark analysis of OS revealed that there is a non-proportional (early) effect of irAEs on OS in ICI-treated cancer patients (landmark >12 weeks, HR(OS) = 1.08; 95% CI: 0.89, 1.30; p = 0.46). CONCLUSION: Our findings suggest that the occurrence of irAEs could be a prognostic factor for cancer patients who were treated with ICIs.