title: Cytokines fused to antibodies and their combinations as therapeutic agents against different peritoneal HER2/neu expressing tumors.
abstract: We have previously generated antihuman HER2/neu-humanized IgG3 fused to interleukin-2 (IL-2), IL-12, or granulocyte macrophage colony-stimulating factor (GM-CSF) [monofunctional fusion proteins (mono-AbFP)] or fused to IL-2 and IL-12 or IL-12 and GM-CSF [bifunctional fusion proteins (bi-AbFP)]. These AbFPs retained cytokine and antigen-binding activities. We have now further characterized the AbFPs and determined the heparin-binding activity of the fused cytokines, their ability to trigger IFN-gamma secretion and natural killer (NK) activation, and their direct antitumor efficacy. Flow cytometry revealed heparin-binding activity in the AbFPs containing IL-12 and IL-2, although this activity seems to be decreased in the bi-AbFPs. However, both bi-AbFPs retained the capacity to stimulate IL-12-dependent IFN-gamma secretion in the NK cell line KY-1, and IL-12/IL-2 bi-AbFP induced NK activity in splenocytes. The antitumor effectiveness of bi-AbFPs and mono-AbFP combinations was studied in mice challenged i.p. with three different human HER2/neu murine syngeneic models (D2F2/E2, CT26-HER2/neu, and MC38-HER2/neu). Although a significant variability in the profile of antitumor response was observed in the different tumor models, the combination of IL-12 and GM-CSF mono-AbFPs protected 100% of D2F2/E2-challenged and 75% of CT26-HER2/neu-challenged mice. In contrast, bi-AbFPs protected less than the combination of mono-AbFPs and, in some models, even less than mono-AbFPs alone. However, in all cases, most of long-term survivors showed protection after s.c. rechallenge with the tumors and later with the parental tumors not expressing HER2/neu. These results show that, although the pattern of protection is tumor model dependent, treatments with AbFPs can effectively generate high levels of protection against peritoneal tumors expressing HER2/neu, which may be relevant in patients with primary or metastatic peritoneal carcinomatosis that may be observed in ovarian, colon, stomach, bladder, lung, and breast cancers.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, University of California, Los Angeles, Box 167817, Los Angeles, CA 90095-1678, USA.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Helguera
authors.forename: José A
authors.initials: JA
authors.lastname: Rodríguez
authors.forename: Manuel L
authors.initials: ML
authors.lastname: Penichet
mesh_terms: D000818:Animals; D000906:Antibodies / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000276:immunology*; D016207:Cytokines / Q000276:immunology* / Q000627:therapeutic use*; D018734:Genes, erbB-2 / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000627:therapeutic use; D018664:Interleukin-12 / Q000627:therapeutic use; D007376:Interleukin-2 / Q000627:therapeutic use; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009101:Multiple Myeloma / Q000188:drug therapy / Q000276:immunology*
chemical_list: D000906:Antibodies; D016207:Cytokines; D007376:Interleukin-2; D018664:Interleukin-12; D016178:Granulocyte-Macrophage Colony-Stimulating Factor