Fimaporfin
Fimaporfin is 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.