We recently reported on the use of CyTOF analysis to describe the changes occurring in peripheral blood immune cells after vaccination with a different VRP-based vaccine encoding the tumor antigen HER2 (VRP-HER2).28 In that study, we also observed the expansion of an antigen-specific, cytolytic CD8 T cell population, suggesting that CyTOF may be a preferred approach for assessing immunogenicity of cancer vaccines. This evidence concerns the gene ERBB2 and cancer.