Effect of bleomycin on hematoporphyrin derivative phototherapy of solid tumors. Hematoporphyrin derivative phototherapy (HpD-PT) has been successfully used to localize and treat superficial squamous cell cancers. Bleomycin sulfate is a glycopeptide antibiotic that has antineoplastic properties against squamous cell cancers. Because both HpD-PT and bleomycin chemotherapy are accepted forms of treatment for squamous cell cancer and their cytotoxicity is mediated by singlet oxygen and oxygen radicals, we studied the possibility of enhancing the response of solid tumors to HpD-PT by combining this modality with systemic bleomycin chemotherapy in a murine tumor model. Bleomycin did not enhance HpD-PT significantly. Also, we are not confident that HpD-PT alone or in combination with other agents can eradicate solid tumors; it certainly did not in this syngeneic murine tumor model. 