title: Therapeutic potential of amanitin-conjugated anti-epithelial cell adhesion molecule monoclonal antibody against pancreatic carcinoma.
abstract: BACKGROUND
  Human epithelial cell adhesion molecule (EpCAM) is overexpressed in many cancers. Anti-EpCAM antibodies have shown promise in preclinical studies, but showed no tumor regression in a recent phase II clinical trial. Therefore, we generated a novel anti-EpCAM antibody-drug conjugate and assessed whether it showed enhanced antitumor effects.
  
  
  METHODS
  Chemical cross-linking was conducted to covalently conjugate α-amanitin, a toxin known to inhibit DNA transcription, with chiHEA125, a chimerized anti-EpCAM monoclonal antibody, to generate the antibody-drug conjugate α-amanitin-glutarate-chiHEA125 (chiHEA125-Ama). Antiproliferative activity of chiHEA125-Ama was tested in human pancreatic (BxPc-3 and Capan-1), colorectal (Colo205), breast (MCF-7), and bile duct (OZ) cancer cell lines in vitro using [(3)H]-thymidine incorporation assay. Antitumor activity of chiHEA125-Ama was assessed in vivo in immunocompromised mice bearing subcutaneous human BxPc-3 pancreatic carcinoma xenograft tumors (n = 66 mice). Cell proliferation and apoptosis were evaluated in xenograft tumors by immunohistochemistry. All statistical tests were two-sided.
  
  
  RESULTS
  In all cell lines, chiHEA125-Ama reduced cell proliferation (mean half maximal inhibitory concentration [IC(50)] = 2.5 × 10(-10) to 5.4 × 10(-12) M). A single dose of chiHEA125-Ama inhibited BxPc-3 xenograft tumor growth (chiHEA125 [control, n = 4 mice] vs. chiHEA125-Ama [n = 6 mice], dose of 15 mg/kg with respect to IgG and 50 μg/kg with respect to α-amanitin, mean relative increase in tumor volume on day 16 = 884% vs. -79%, difference = 963%, 95% CI = 582% to 1344%, P = .019). Two higher doses of chiHEA125-Ama (100 μg/kg with respect to α-amanitin), administered 1 week apart (n = 10 mice per group), led to complete tumor regression in nine of 10 (90%) mice compared with chiHEA125, during the observation period of 16 days; increased apoptosis and reduced cell proliferation were observed in mice treated with chiHEA125-Ama.
  
  
  CONCLUSIONS
  This preclinical study suggests that anti-EpCAM antibody conjugates with α-amanitin have the potential to be highly effective therapeutic agents for pancreatic carcinomas and various EpCAM-expressing malignancies.
authors.affiliation: Department of Translational Immunology (D015), German Cancer Research Center, Im Neuenheimer Feld 280, Heidelberg 69120, Germany. g.moldenhauer@dkfz.de
authors.forename: Gerhard
authors.initials: G
authors.lastname: Moldenhauer
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Salnikov
authors.forename: Sandra
authors.initials: S
authors.lastname: Lüttgau
authors.forename: Ingrid
authors.initials: I
authors.lastname: Herr
authors.forename: Jan
authors.initials: J
authors.lastname: Anderl
authors.forename: Heinz
authors.initials: H
authors.lastname: Faulstich
mesh_terms: D053959:Alpha-Amanitin / Q000276:immunology / Q000494:pharmacology*; D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000276:immunology / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology*; D014408:Biomarkers, Tumor / Q000276:immunology / Q000378:metabolism*; D002277:Carcinoma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002678:Chimera; D003110:Colonic Neoplasms / Q000188:drug therapy; D004791:Enzyme Inhibitors / Q000276:immunology / Q000494:pharmacology*; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D018796:Immunoconjugates / Q000276:immunology / Q000494:pharmacology*; D007150:Immunohistochemistry; D008099:Liver / Q000201:enzymology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D015854:Up-Regulation / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D053959:Alpha-Amanitin; D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D004791:Enzyme Inhibitors; D000071858:Epithelial Cell Adhesion Molecule; D018796:Immunoconjugates; C115012:human epithelial antigen-125