Definition

A synthetic light-activated compound composed of three benzenesulfonic acid isomers: fimaporfin A (TPCS2a; tetraphenyl chlorin disulfonate), fimaporfin B, and fimaporfin C, with potential photosensitizing activity upon photodynamic therapy (PDT) . Upon intradermal administration, fimaporfin is incorporated into the tumor cells’ endosome and lysosome membranes. Subsequently, cytotoxic agents are administered and accumulate in the endosomal and lysosomal compartments; upon local activation by light, fimaporfin produces reactive oxygen species (ROS), such as singlet oxygen, damaging endo/lysosomal membranes and accumulated cytotoxic agents are released into the tumor cell cytosol. This photochemical internalization (PCI) method can enhance the efficacy and selectivity of cytotoxic agents.