Basics of photodynamic therapy for malignant brain tumors

Abstract

Photodynamic therapy (PDT) for primary malignant brain tumors has now been approved for coverage under Japanese national health insurance. In this therapy, talaporfin sodium (Laserphyrin®) is used as a photosensitizer to be used along with an exclusively developed laser beam source. PDT is a tumor-selective, bimodal treatment, that is based on various photodynamic reactions involving molecular oxygen and oxygenated products, which are harmful for tumor tissue. After administration, the photosensitizer is accumulated and localized in the tumor tissue, which is then exposed to a laser beam with a wavelength appropriate for absorption by the sensitizer, providing photodynamic reactions. The treatment rationale, characteristics of talaporfin sodium and the laser source used for PDT of malignant brain tumors are also described.