A substance that is being studied in the treatment of cancer using photodynamic therapy. It belongs to the family of drugs called metallotexaphyrins. Also called lutetium texaphyrin. Or A pentadentate aromatic metallotexaphyrin with photosensitizing properties. Motexafin lutetium preferentially accumulates in tumor cells due to their increased rates of metabolism and absorbs light, forming an extended high energy conformational state that produces high quantum yields of singlet oxygen, resulting in local cytotoxic effects.