Recent Progresses in Phototherapy-Synergized Cancer Immunotherapy

Cancer immunotherapy has recently gained much attention in the search of cancer cure due to its ability to “train” the immune system in seeking out and removing residual tumor cells. However, relying on cancer immunotherapy alone may fail to ablate primary tumors. Phototherapy is a promising modality that offers an elegant solution to eradicate tumors through the simple application of light irradiation and meanwhile triggers immune responses by immunogenic cell death to enhance antitumor immunity. Uniting phototherapy with cancer immunotherapy has been found to achieve synergistic outcomes, promote cancer regression, and even attain immunologic memory. This review summarizes the recent studies on utilizing phototherapy and immunotherapy combinatorial approaches to treat cancer. A variety of nanoplatforms have been investigated in combination with immunoadjuvants and immune checkpoint blockades such as CTLA4 and PD-L1 pathways. Higher levels of proinflammatory cytokines, improved migration of dendritic cells, and an increased ratio of tumor-infiltrating cytotoxic T cells against regulatory T cells are revealed in many studies, offering a glimpse into the mechanistic principles. Future advancements targeting different cancer checkpoints that could offer better immunosuppression coupled with other phototherapeutic strategies remain to be explored in accomplishing complete elimination of cancer.