Site-Specific Drug Delivery by Photochemical Internalization Enhances the Antitumor Effect of Bleomycin

Abstract

Purpose: Photochemical internalization is under development for improving macromolecular therapy by inducing photochemical damage to endocytic vesicles. This damage leads to the release of therapeutic macromolecules entrapped in endocytic vesicles into the cytosol. The macromolecules may in this way be able to interact with therapeutic targets instead of being degraded by lysosomal hydrolases. Bleomycin is used in several standard cancer chemotherapy regimens. Its hydrophilic and relatively large chemical structure limits its ability to penetrate membrane structures, which causes the accumulation of bleomycin in endocytic vesicles. The purpose of this study was to evaluate the therapeutic potential of aluminum phthalocyanine disulfonate (AlPcS_2a)–based photochemical delivery of bleomycin.