Immune-related adverse events associated with immune checkpoint inhibitors for advanced gastric and gastroesophageal junction cancer: A meta-analysis

BACKGROUND: Immune checkpoint inhibitors (ICIs) have shown promising efficacy in treatment and clinical management of advanced gastric and gastroesophageal junction cancer. However, the inhibitors also cause immune-related adverse events (irAEs). The current systematic review and meta-analysis study aimed to investigate the incidence and nature of irAEs caused by ICIs. AIM: To investigate the incidence and nature of irAEs in advanced gastric and gastroesophageal junction cancer. METHODS: This systematic review was registered with PROSPERO (Reg. number: CRD42020152291). Data included in this study were collected from patients diagnosed with advanced gastric cancer or gastroesophageal junction cancer and treated with ICIs. A systematic literature search was conducted using the PubMed, EMBASE, and Cochrane Library databases. Meta-analysis was carried out using the single sample rate method. Synthesis and analysis of the data was conducted using Stata/SE and Review Manager Software. RESULTS: The patients enrolled in the present study included 14 patients from 14 case reports, 326 patients from 6 case series, and 1249 patients from 8 clinical trials. It was found that the overall incidence of irAEs was 16% [95% confidence interval (CI): 11-20] for all grades and 3% (95%CI: 2-4) for the severe grade. It was evident that the incidence of irAEs varied with the type of inhibitor and organs. A comparative study of the anti-programmed cell death receptor-1 (PD-1) and anti-programmed death receptor-ligand 1 (PD-L1) treatments showed that the anti-PD-1 group had a higher overall incidence of irAEs (20%) as compared with that of the anti-PD-L1 group (13%). Results of this study showed that the endocrine system experienced the highest incidence of organ-specific irAEs (7.4%), including hypothyroidism, hyperthyroidism, thyroiditis, diabetes, and adrenal insufficiency, followed by gastroenterology (2.2%), pulmonology (1.8%), neurology (1.4%), dermatology (1.4%), hematology (0.8%), and hepatology (0.7%). In clinical trials, it was found that the incidence of death related to irAEs was 1% (95%CI: 0-2.0), whereby colitis and interstitial lung diseases were the leading causes of death. CONCLUSION: It was evident that the incidence and nature of irAEs are both organ- and inhibitor-specific. The anti-PD-1 group had the highest incidence of all irAEs grades including the severe grades of irAEs. Early identification and management of irAEs allows clinical oncologists to effectively consider the pros and cons and hence enables them to strike a balance.