**Abstract**

Reports in the literature show that certain vaccines against infectious pathogens, can be effective in eliciting antitumor immune response when injected intratumorally. In mouse tumor models, intratumoral delivery of rotavirus, yellow fever, and influenza vaccines have been shown to also synergize with checkpoint inhibitors, in the leading immunotherapy in the clinical practice today. The combined approach can thus become a very promising novel strategy for anticancer immunotherapy. In humans, an attenuated poliomyelitis virus vaccine, a peptide-based vaccines against papilloma and one based on detoxified diphtheria protein have already been tested as intratumoral treatments readily. In those studies, the role of available anti-pathogen immunity appears an important element in mediating the activity of the repurposed vaccines against cancer. We therefore suggest how evaluating or eventually developing anti-pathogen immunity before intratumoral delivery could be helpful in repurposing infectious pathogen vaccines in cancer immunotherapy.

**Keywords:** cancer immunotherapy, cancer vaccines, repurposed vaccines, infectious agents vaccines, intratumoral delivery
