Biomimetic Nanoemulsion for Synergistic Photodynamic‐Immunotherapy Against Hypoxic Breast Tumor

Abstract Photodynamic therapy (PDT) is commonly used as an “in situ vaccine” to enhance the response rate of PD‐1/PD‐L1 antibodies. Unfortunately, the high cost and adverse effects of these antibodies, and the hypoxic state of solid tumors limits the efficacy of synergistic photodynamic‐immunotherapy. Here, we developed a biomimetic nanoemulsion camouflaged with a PD‐1‐expressing cell membrane for synergistic photodynamic‐immunotherapy against hypoxic breast tumors. The perfluorocarbon of the nanoemulsion could provide oxygen as the source of PDT against hypoxic tumors. Moreover, co‐delivering a photosensitizer and the PD‐1 protein (substituting for a PD‐L1 antibody) achieves the synergy effect of PDT and immunotherapy. Synergistic photodynamic‐immunotherapy completely inhibited primary and distant subcutaneous 4T1 tumors, mechanistically by boosting the maturation of dendritic cells and tumor infiltration of cytotoxic T lymphocytes.