Targeted photodynamic immunotherapy

Abstract Photodynamic therapy (PDT), a minimally-invasive therapeutic strategy, comprises a topical or systemic administration of a photosensitizer followed by selective irradiation of the target lesion. PDT is a promising alternative approach for cancer therapy which can directly destroy local tumor cells due to the release of cytotoxic reactive oxygen species at the tumor site. Importantly, PDT also induces immunological cell death, triggering an acute immune response that further potentiate PDT-mediated cell death. Nevertheless, some regulatory immune mechanisms can arise, limiting the immune response induced by PDT. The combination with immunotherapeutic approaches, like immune checkpoint inhibitors, is therefore necessary to reduce the immunosuppression at the tumor microenvironment and potentiate the antitumor immunity. Here, we explored the recent advances in the combinatory PDT immunotherapy and its current limitations for clinical translation.