Influenza Vaccination in Cancer Patients Treated With Immune Checkpoint Inhibitors: A Systematic Review and Meta-analysis

Abstract

The safety and efficacy of influenza vaccination is not well-studied in cancer patients receiving immune checkpoint inhibitors (ICIs). A systematic review and meta-analysis was performed aiming to summarize available data regarding influenza vaccination in ICI-treated cancer patients. Peer-reviewed studies or nonpeer-reviewed conference abstracts including ICI-treated cancer patients who received at least 1 dose of influenza vaccine were deemed eligible. A systematic search in PubMed/EMBASE was performed until October 26, 2021. Endpoints of interest included mortality as the primary outcome and secondary safety outcomes such as the incidence of immune-related adverse events (irAEs). Twenty-five studies were included in the systematic review, among which 9 were included in the meta-analysis. Meta-analysis of 3 studies (n=589, weighted age 64 y, men 61%, influenza vaccinated 32%) showed pooled odds ratio for death in influenza vaccinated versus nonvaccinated patients at 1.25 [(95% confidence intervals (CI): 0.81-1.92), P=non significant (NS)]. Meta-analysis of 6 studies studies (n=1285, weighted age 60 y, men 59%, influenza vaccinated 48%) showed pooled odds ratio for any irAEs in influenza vaccinated versus nonvaccinated patients at 0.82 [95% CI: 0.63-1.08, P=NS]. Similar results were observed in sensitivity analyses for serious irAEs, as well as when only peer-reviewed studies were included. Influenza vaccination appears to be a safe and reasonable intervention for cancer patients receiving ICIs. Most data are derived from retrospective observational studies. Randomized studies are needed to provide high-quality evidence.