CGP 55 847, liposome-delivered zinc(II)-phthalocyanine as a phototherapeutic agent for tumors

Zinc(II)-phthalocyanine (Zn-Pc) was chosen for development as a second-generation photosensitizer for photodynamic therapy (PDT) of tumors and for benign conditions because of its advantageous chemical and photophysical properties. Zn-Pc displayed good selectivity for malignant tissue in pharmacokinetic studies with Meth-A-sarcoma-bearing BALB/c mice when injected in a dose of 0.125 mg/kg, delivered by CGP 55 847. Intravenous doses of Zn- Pc ranging from 0.032 to 0.375 mg/kg caused tumor necrosis and, subsequently, cure of Meth-A-sarcoma-bearing mice when phototreatment was performed 48 hours after injection of CGP 55 847. Intravenous injection of Zn-Pc into hairless mice in doses ranging from 0.1 to 1.0 mg/kg caused dose- and time-dependent phototoxicity. We conclude that the promising pharmacological properties of liposomally delivered Zn-Pc, along with its advantageous chemical and photophysical properties, warrant the development of CGP 55 847 as a candidate drug for photodynamic therapy of tumors in humans.