Photodynamic activity of lutetium-texaphyrin in a mouse tumor system

Background and Objective: New photosensitizers proposed for photodynamic th erapy (PDT) treatment of tumors need to be evaluated in animal models to de termine the parameters needed for treatment. They also need to be compared with existing photosensitizers for efficacy. We examined the PDT response t o lutetium-texaphyrin (PCI-0123) in a mouse mammary adenocarcinoma model an d compared it with the PDT response seen when using Photofrin(R). Study Design/Materials and Methods: DBA/2 mice with SMT-F tumors were used to explore PCI-0123 toxicity, laser light dose, and drug dose effects on PD T response and to determine the most effective time for light application. The PDT response of PCI-0123-treated tumors was compared with that of Photo frin(R)-itreated tumors. Results: Treatment of tumors with 150 J/cm(2) of 740 nm laser light 5-6 hr after PCI-0123 administration (40 mg/kg) resulted in a 100% response rate a nd a 55% cure rate. Tumors treated with 150 J/cm(2) of 630 nm laser light 2 4 hr after Photofrin (R) administration (10 mg/kg) resulted in a 67% respon se rate and a 16% cure rate. Conclusion: PCI-0123 was found to be a more effective photosensitizer than Photofrin(R). (C) 1999 Wiley-Liss, Inc.