CD4 and neoplasm: The results demonstrated that TBP‐NMOF‐induced PDT could not only kill the 4T1 murine breast tumor cells, but also augment the presentation of tumor‐activated antigens, further stimulating adaptive immune response for initiating the secretion of inflammatory cytokines (IFN‐γ, TNF‐α) and recruiting tumor‐infiltrating T cells (CD4+, CD8+).