title: Interferon enhancement of radioimmunotherapy for colon carcinoma.
abstract: Recombinant human gamma-interferon (IFN-gamma) has recently been shown to enhance localization of radiolabeled monoclonal antibodies (MAb) to human colon carcinoma xenografts in athymic mice. The present study investigates the ability of gamma-interferon to enhance radioimmunotherapy of a low carcinoembryonic antigen-expressing human colon cancer (WiDr) in athymic mice. Growth curve analysis, antibody localization, and dose estimation studies were performed. A significant tumor growth delay, measured as the time to reach 1.0 g, was noted for animals receiving specific anti-carcinoembryonic antigen 90Y-MAb (ZCE025, 120 microCi) plus IFN-gamma (61.8 days) as compared to animals that received specific 90Y-MAb with phosphate-buffered saline (34.9 days; P less than 0.005). IFN-gamma (100,000 units) was given i.p. every 8 h for 2 days before and 4 days after 90Y-MAb therapy. The time required to reach 1.0 g for animals treated with nonspecific 90Y-MAb (ZME018) was significantly less either with (38.3 days) or without (34.4 days) IFN-gamma. The difference was more apparent when compared to animals receiving IFN-gamma alone (30.0 days) or phosphate-buffered saline alone (28.9 days; P less than 0.001). Increased antibody localization in the tumors of animals treated with IFN-gamma plus specific 90Y-MAb (43.2% injected dose/g) was seen in comparison to animals treated with specific 90Y-MAb without IFN-gamma (18.2% injected dose/g). The estimate of radiation dose delivered to the tumors, based on biodistribution data over time, revealed significantly higher levels in animals treated with specific 90Y-MAb with IFN-gamma (2477 cGy) compared to animals treated without IFN-gamma (1217 cGy). These results provide support for the use of gamma-interferon as an immunomodulating agent prior to radioimmunotherapy.
authors.affiliation: Department of General Oncologic Surgery, City of Hope National Medical Center, Duarte, California 91010.
authors.forename: J A
authors.initials: JA
authors.lastname: Kuhn
authors.forename: B G
authors.initials: BG
authors.lastname: Beatty
authors.forename: J Y
authors.initials: JY
authors.lastname: Wong
authors.forename: J M
authors.initials: JM
authors.lastname: Esteban
authors.forename: P M
authors.initials: PM
authors.lastname: Wanek
authors.forename: F
authors.initials: F
authors.lastname: Wall
authors.forename: R R
authors.initials: RR
authors.lastname: Buras
authors.forename: L E
authors.initials: LE
authors.lastname: Williams
authors.forename: J D
authors.initials: JD
authors.lastname: Beatty
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000627:therapeutic use*; D002272:Carcinoembryonic Antigen / Q000276:immunology* / Q000378:metabolism; D003110:Colonic Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy; D005260:Female; D007167:Immunotherapy / Q000379:methods*; D007371:Interferon-gamma / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D015021:Yttrium Radioisotopes / Q000627:therapeutic use*
chemical_list: D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D015021:Yttrium Radioisotopes; D007371:Interferon-gamma