Enhancement of anti-tumor immunity by photodynamic therapy

Photodynamic therapy (PDT) is an FDA-approved modality that rapidly eliminates local tumors, resulting in cure of early disease and palliation of advanced disease. PDT was originally considered to be a local treatment; however, both pre-clinical and clinical studies have shown that local PDT treatment of tumors can enhance systemic anti-tumor immunity. The current state of investigations into the ability of PDT to enhance anti-tumor immunity, the mechanisms behind this enhancement and the future of PDT as an immunotherapy are addressed in this review.