Biomedical applications of lanthanide (III) texaphyrins Lutetium(III) texaphyrins as potential photodynamic therapy photosensitizers

The texaphyrins are a novel class of pentadentate, porphyrin-like aromatic macrocyclic ligands that form kinetically stable complexes with essentially all cations of the trivalent lanthanide series. This ability, combined with certain features inherent to the texaphyrin skeleton, gives rise to species that are of potential interest in a range of medical applications including diagnosis and therapy. In this paper, the biomedical utility of one particular metallotexaphyrin derivative, namely the lutetium(III) complex PCI-0123 (1), is highlighted. This system generates singlet oxygen in 11% quantum yield in water (20–30% in organic solvents) and is an effective sensitizer for photodynamic cancer therapy as judged from animal model studies. It is currently in Phase I human clinical trials.