Vaccination and Immune Checkpoint Inhibitors: Does Vaccination Increase the Risk of Immune-related Adverse Events? A Systematic Review of Literature.

Introduction Immune checkpoint inhibitors (ICIs) have become part of cancer treatments. Their main side effects are immune-related adverse events (irAEs). So far, there has been no recommendation regarding routine vaccinations during ICIs treatment. Clinicians are aware of the risk of irAEs increases in this specific situation. The aim of this review of literature is to summarize the main studies about vaccination and ICIs interactions. Methods A systematic assessment of literature articles was performed by searching in PubMed (MEDLINE), and major oncology meeting following PRISMA guidelines. Results This review highlights the lack of literature. Indeed, most of the studies published were about influenza vaccination. Vaccination for patients under ICIs causes a humoral response and seems to be associated with an increase rate of seroconversion. Interestingly vaccination may provoke irAEs in ICIs-treated patients. So far, inactivated vaccines have not been contraindicated during ICI treatment. Conclusion Larger prospective studies are needed in order to define a consensus on the use of vaccines under immunotherapy.