The enhanced secretion of TNF‐α and IFN‐γ by activated T cells indicates that Th1 responses were stimulated.[53, 54] However, we did not observe an increase in the production of IL‐2, the main cytokine produced during the primary reaction of Th1 cells, in vaccinated mice (Figure S9A, Supporting Information)[55] Furthermore, we evaluated the infiltration of T cells into the tumor microenvironment using IHC staining of CD4 and CD8. Here, CD4 is linked to neoplasm.