Does prior exposure to immune checkpoint inhibitors treatment affect incidence and mortality of COVID-19 among the cancer patients: The systematic review and meta-analysis

Background: Immune checkpoint inhibitors (ICIs) treatment among cancer patients has been shown to have antiviral effects by reactivating exhausted T cells. However, they could also trigger inflammatory storm. Therefore, prior exposure to ICIs may influence the risk of SARS-CoV2 infection and subsequent mortality. Recent results from studies of ICIs treatment on incidence and mortality of COVID-19 are controversial. Materials and methods: We searched databases PubMed, Embase, ISI of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), as well as pre-print databases (MedRxiv and BioRxiv) for retrospective and prospective studies comparing ICIs versus other antitumor treatments in cancer patients in the area of COVID-19 pandemic. The primary outcome was the incidence of COVID-19. The secondary outcomes were mortality of COVID-19. Results: Twenty-three studies with a total of 117,735 patients were selected. Compared with other antitumor treatments, prior exposure to ICIs had not an increased risk of incidence [Odds ratio (OR), 0.84; 95% confidence interval (CI), 0.60-1.18; P = 0.32] and mortality (OR, 1.22; 95% CI, 0.91-1.62; P = 0.18) of COVID-19 infectioin. Our subgroup and meta-regression analyses indicated that prior exposure to ICIs may reduce the incidence of COVID-19 in metastatic cancer patients. Conclusions: There was no significant difference on incidence and mortality of COVID-19 between prior exposure to ICIs with other anti-tumor treatments. ICIs may reduce infection susceptibility of COVID-19 in metastatic cancer patients.