title: Interleukin-12 induces an effective antitumor response in malignant mesothelioma.
abstract: Malignant mesothelioma (MM) is a fatal solid tumor of the mesothelium for which there is currently no ameliorating treatment. Using our murine model of this malignancy, which closely resembles the human disease, we have shown that immunotherapy may be of value in the treatment of MM. Because recombinant interleukin-12 (rIL-12) has strong immunomodulatory effects in vivo, we studied the effects of rIL-12 on murine antitumor immune responses, using a nonimmunogenic murine MM tumor cell line (AB1) in vivo. Systemic administration of rIL-12 at the time of tumor inoculation prevented AB1 tumor growth in up to 70% of treated mice, 50% of which were still resistant to AB1 upon rechallenge, indicating that long-term immunologic antitumor effects had been established. This rIL-12-induced effect was dependent on the involvement of both CD4(+) and CD8(+) but not natural killer (NK) cells. Importantly, treatment of established tumors with intralesional injections of rIL-12 resulted in temporary tumor regression or growth inhibition. This effect was dependent on the continuous presence of rIL-12 and correlated with increased numbers of CD4(+) and CD8(+) cells infiltrating the remaining tumor mass. Effective inhibition of tumor growth also occurred when IL-12 was released within MM tumors by coadministration of MM cells that had been stably transfected with the gene for IL-12. These data indicate that IL-12 has potential in the immunotherapy of MM, through gene transfer or local cytokine administration, provided that significant intratumor levels of IL-12 can be achieved for prolonged periods.
authors.affiliation: University Department of Medicine, University of Western Australia, and Australian Neuromuscular Research Institute, Queen Elizabeth II Medical Centre, Nedlands, Australia.
authors.forename: I
authors.initials: I
authors.lastname: Caminschi
authors.forename: E
authors.initials: E
authors.lastname: Venetsanakos
authors.forename: C C
authors.initials: CC
authors.lastname: Leong
authors.forename: M J
authors.initials: MJ
authors.lastname: Garlepp
authors.forename: B
authors.initials: B
authors.lastname: Scott
authors.forename: B W
authors.initials: BW
authors.lastname: Robinson
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015704:CD4 Antigens / Q000276:immunology; D002455:Cell Division / Q000187:drug effects; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000097:blood; D018664:Interleukin-12 / Q000276:immunology / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000276:immunology; D008654:Mesothelioma / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology; D014162:Transfection / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D000276:Adjuvants, Immunologic; D000970:Antineoplastic Agents; D015704:CD4 Antigens; D011994:Recombinant Proteins; D018664:Interleukin-12; D007371:Interferon-gamma