Introduction to Drugs for Photodynamic Therapy of Malignant Tumors

Abstract

Photodynamic therapy (PDT) offers a safer alternative to surgery, chemotherapy, and radiotherapy for cancer treatment. Photosensitizers (PS) accumulate selectively in tumor cells and, upon specific-wavelength light activation, generate singlet oxygen that oxidizes DNA, inducing apoptosis and activating the STING pathway for antitumor M1 macrophage polarization. Originating from Oskar Raab's 1900 discovery with eosin, PDT advanced in the 1970s via hematoporphyrin derivatives, despite issues like skin photosensitivity. Improved second-generation PS, such as chlorin e6 and pheophorbide a from chlorophyll, provide better absorbance at 664 nm for deeper tumors and efficacy against colorectal cancer, melanoma, and glioblastoma. Phthalocyanines and curcumin conjugates show further promise. Polymer delivery systems like PVP enhance bioavailability, prevent aggregation, boost light absorption, and target tumors selectively, reducing side effects. This review synthesizes PDT's mechanisms, evolution, and delivery innovations, underscoring its potential in oncology.