CGP55847, liposomal zinc(II)-phthalocyanine (Zn-Pc), was administered by the intravenous route to Swiss mice bearing intramuscularly implanted Ehrlich carcinomas or to C57/BL6 mice bearing subcutaneously implanted B16 melanomas. Tumors were removed 3 h or 24 h after dosing the intratumoral distribution determined by fluorescence microscopy. Localization of the photosensitizer occurred more rapidly in the Ehrlich carcinoma than in the B16 melanoma; this difference in photosensitizer uptake may be related to a higher degree of vascularization of the carcinoma. The photosensitizer was found in association with blood vessels at 3 h but not 24 h after dosing and appeared to have a greater affinity for areas of tissue necrosis within the tumor compared to viable tumor tissue. Little or no Zn-Pc was detected in the muscle tissue invaded by the Ehrlich carcinoma and was associated with the membranes and the cytosol, but not the nucleus, of cells in both tumors.

The liposomal zinc(II) phthalocyaninc (Zn-Pc) formulation CGP55847 was administered intravenously (0.5mg Zn-Pc/kg) to C57/BL6 mice bearing subcutaneously implanted B 16 melanomas or to Swiss mice bearing intramuscularly implanted Ehrlich carcinomas. Tumours were removed 3 or 24h after dosing, and the Zn-Pc content and intratumoral distribution determined by extraction and quantitative fluorescence microscopy. Localisation of the photosensitiser within the tumour mass occurred more rapidly in the highly vascularised Ehrlich carcinoma compared to the less highly vascularised B16 melanoma. Zn-Pc was evident in and around blood vessels 3 but not 24h after dosing. More Zn-Pc was found in necrotic areas compared to viable tumour tissue; little or no Zn-Pc was detected in the muscle tissue invaded by the Ehrlich carcinoma. At the cellular level, Zn-Pc was associated with membranes and the cytosol but not the nucleus.