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.

CONCLUSION:

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: Gerhard Moldenhauer, Alexei V Salnikov, Sandra Lüttgau, Ingrid Herr, Jan Anderl, Heinz Faulstich
• Journal: Journal of the National Cancer Institute (J Natl Cancer Inst) Vol. 104 Issue 8 Pg. 622-34 (Apr 18 2012) ISSN: 1460-2105 [Electronic] United States
• PMID: 22457476 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Alpha-Amanitin
• Angiogenesis Inhibitors
• Antibodies, Monoclonal
• Antigens, Neoplasm
• Antineoplastic Agents
• Biomarkers, Tumor
• Cell Adhesion Molecules
• EPCAM protein, human
• Enzyme Inhibitors
• Epithelial Cell Adhesion Molecule
• Immunoconjugates
• human epithelial antigen-125

Topics

• Alpha-Amanitin (immunology, pharmacology)
• Angiogenesis Inhibitors (pharmacology)
• Animals
• Antibodies, Monoclonal (immunology, pharmacology)
• Antigens, Neoplasm (immunology, metabolism)
• Antineoplastic Agents (immunology, pharmacology)
• Biomarkers, Tumor (immunology, metabolism)
• Carcinoma (drug therapy, immunology, pathology)
• Cell Adhesion Molecules (immunology, metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Chimera
• Colonic Neoplasms (drug therapy)
• Enzyme Inhibitors (immunology, pharmacology)
• Epithelial Cell Adhesion Molecule
• Female
• Flow Cytometry
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Immunoconjugates (immunology, pharmacology)
• Immunohistochemistry
• Liver (enzymology)
• Mice
• Mice, Inbred NOD
• Mice, SCID
• Pancreatic Neoplasms (drug therapy, immunology, pathology)
• Up-Regulation (drug effects)
• Xenograft Model Antitumor Assays