title: Photoimmunotherapy: treatment of animal tumors with tumor-specific monoclonal antibody-hematoporphyrin conjugates.
abstract: The term "photoimmunotherapy" describes an anti-cancer treatment that combines the phototoxic effects of chemical such as hematoporphyrin and the target-seeking ability of antibodies. Hematoporphyrin was chemically coupled to monoclonal antibodies directed to the DBA/2J myosarcoma M-1. Administration of anti-M-1-hematoporphyrin conjugates i.v. to M-1 tumor-bearing animals followed by exposure to incandescent light resulted in suppression of M-1 growth. The time interval between injection and light exposure was an important parameter in terms of tumor suppression. Tumor-bearing animals maintained in the dark for 96 to 196 hr after hematoporphyrin-antibody injection followed by 4-hr light exposure demonstrated significantly lower tumor incidence and longer latency periods, in comparison to conjugate-treated animals instantly exposed to light. The growth inhibiting properties of the conjugate appeared to be M-1-specific; it had no effect on the growth of a C57BL/6J lymphoma EL4. In addition, conjugates made with a nonspecific monoclonal antibody did not have any specific anti-tumor effect on M-1 growth. Treatment with equivalent doses of hematoporphyrin or antibody had no significant inhibiting effect on tumor growth. Clearly, the homing ability of the specific monoclonal antibody-hematoporphyrin conjugate was essential for effective drug delivery and inhibition of tumor growth.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D000939:Epitopes; D005260:Female; D006415:Hematoporphyrins / Q000627:therapeutic use*; D006825:Hybridomas / Q000276:immunology; D007167:Immunotherapy; D008223:Lymphoma / Q000628:therapy; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010789:Phototherapy; D012208:Rhabdomyosarcoma / Q000628:therapy
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006415:Hematoporphyrins