Effect of Route of Administration on the Selectivity of Hematoporphyrin Derivative for Tumor Tissue

Abstract

Hematoporphyrin derivative (HPD) has the ability to localize with moderate selectivity to tumor tissue, where it can be activated by visible light and produce singlet oxygen-mediated damage to cellular biomolecules. However, HPD is less than ideal as an agent for tumor photoradiation therapy because it produces a period of photosensitivity that can last 30 days or more, and it can be toxic to surrounding tissues such as skin when used in the treatment of subcutaneous metastases. The usefulness of intra-arterial injection for refining the selectivity of HPD was investigated in this work. Intraarterial administration of HPD was not found to provide higher tumor levels of HPD, nor was it able to increase significantly the concentration of HPD relative to surrounding tissues, such as skin and muscle. However, fluorescence microscopy findings suggested that some fluorescent HPD component is rapidly accumulated in tumor macrophages following intraarterial injection.