A comparative study of hematoporphyrin derivative, photofrin II and uroporphyrin in tumor localization

Hematoporphyrin derivative (HPD) a complex mixture of at least six different dicarboxylic porphyrins, has been studied for its potential utilization as a tumor localizer both as a diagnostic marker of early cancer (flourescent properties) and for photoradiation therapy of malignancy (photodynamic properties). The basis for its use is its relative abundance in neoplastic as opposed to normal tissue. However, there are several disadvantages which limit its clinical usefulness. Firstly, there is significant retention by normal skin for periods of 4 to 6 weeks. Thus, patients suffer a photocutaneous syndrome like that of the human disease, porphyria and have to avoid excessive exposure to sunlight for 4-6 weeks after a single intravenous injection. The retention by skin limits the dose of light used in the treatment of skin tumors in that neighboring normal skin may undergo photodynamic damage. With regard to mucosal HPD uptake, no studies documenting porphyrin content in normal and neoplastic tissues have been published in humans and it has been used on a limited basis both in bronchogenic and bladder carcinoma. There has been no application in gastrointestinal malignancy to date. We were the first to report the tumor localization of uroporphyrin (UROP) I and III (1,2,3). The purpose of this paper is to review data that suggests UROP has superior qualities with regard to tumor localization, with miminal skin and gut mucosal retention. A porphyrin with these characteristics could be the basis of wide application in the clinical arena. In this report, we conducted a comparative study on the tumor localization of uroporphyrin, HPD and Photofrin II using mouse mammary carcinoma, and rats bearing hepatoma and fibrosarcoma as models.