Photodynamic therapy of cancer-Challenges of multidrug resistance

Photodynamic therapy(PDT)of cancer is a two-step drug device combination modality,which involves the topical or systemie administration of a photosensitizer followed by light ilumnination of cancer site.In the presence of oxygen molecules,the light illmnination of photosensitizer(PS)can lead to the generation of cytotoxic reactive oxygen species(ROS)and consequently destroy cancer.Similar to many other anticancer therapies,PDT is also subject to intrinsic cancer resistance mediated by mutidrug resistance(MDR)mechanisms.This paper will review the recent progress in understanding the interaction between MDR transporters and PS uptalke.The strategies that can be used in a clinical setting to owercome or bypass MDR will also be discussed.