This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Di Paolo, C. Articles by Zangemeister-Wittke, U. Search for Related Content PubMed PubMed Citation Articles by Di Paolo, C. Articles by Zangemeister-Wittke, U.

A Recombinant Immunotoxin Derived from a Humanized Epithelial Cell Adhesion Molecule-specific Single-Chain Antibody Fragment Has Potent and Selective Antitumor Activity¹

Clinic and Policlinic for Oncology, University Hospital, CH-8044 Zürich [C. D. P., I. L., R. A. S., U. Z-W.]; Clinic of Otorhinolaryngology, Head and Neck Surgery, University Hospital, CH-8091 Zürich [D. T.]; Department of Biochemistry, University of Zürich, CH-8057 Zürich [J. W., S. K., A. P.]; and Center for Radiopharmaceutical Science, Paul Scherrer Institute, CH-5232 Villigen [R. W.], Switzerland

Purpose: Epithelial cell adhesion molecule (Ep-CAM) is a tumor-associated antigen overexpressed in many solid tumors but shows limited expression in normal epithelial tissues. To exploit this favorable expression pattern for targeted cancer therapy, an Ep-CAM-specific recombinant immunotoxin was developed and its antitumor activity investigated.

Experimental Design: The immunotoxin 4D5MOCB-ETA was developed by genetically fusing a truncated form of Pseudomonas aeruginosa exotoxin A (ETA) (ETA_252–608KDEL) to the highly stable humanized single-chain antibody fragment (scFv) 4D5MOCB. Cytotoxicity of 4D5MOCB-ETA was measured in cell growth and leucine incorporation assays in vitro. Tumor localization and antitumor activity were assessed in athymic mice bearing established human tumor xenografts.

Results: Fusion of the toxin moiety to the scFv did neither affect its thermal stability nor its antigen-binding affinity. In vitro, 4D5MOCB-ETA potently and specifically inhibited protein synthesis and reduced the viability of Ep-CAM-positive carcinoma cells of diverse histological origins with IC₅₀s ranging from 0.005 to 0.2 pM. Upon systemic administration in mice, 4D5MOCB-ETA showed similar organ distribution as the scFv 4D5MOCB and preferentially localized to Ep-CAM-positive tumor xenografts with a tumor:blood ratio of 5.4. The potent antitumor activity of 4D5MOCB-ETA was demonstrated by its ability to strongly inhibit the growth and induce regression of relatively large tumor xenografts derived from lung, colon, or squamous cell carcinomas.

Conclusions: We describe for the first time the development of a fully recombinant Ep-CAM-specific immunotoxin and demonstrate its potent activity against solid tumors of various histological origins. 4D5MOCB-ETA is currently being evaluated in a Phase I study in patients with refractory squamous cell carcinoma of the head and neck.

This article has been cited by other articles:

				A. Honegger, A. D. Malebranche, D. Rothlisberger, and A. Pluckthun The influence of the framework core residues on the biophysical properties of immunoglobulin heavy chain variable domains Protein Eng. Des. Sel., March 1, 2009; 22(3): 121 - 134. [Abstract] [Full Text] [PDF]

				S. Hussain, A. Pluckthun, T. M. Allen, and U. Zangemeister-Wittke Antitumor activity of an epithelial cell adhesion molecule targeted nanovesicular drug delivery system Mol. Cancer Ther., November 1, 2007; 6(11): 3019 - 3027. [Abstract] [Full Text] [PDF]

				M. Trzpis, P. M.J. McLaughlin, L. M.F.H. de Leij, and M. C. Harmsen Epithelial Cell Adhesion Molecule: More than a Carcinoma Marker and Adhesion Molecule Am. J. Pathol., August 1, 2007; 171(2): 386 - 395. [Abstract] [Full Text] [PDF]

				B. J. Stish, H. Chen, Y. Shu, A. Panoskaltsis-Mortari, and D. A. Vallera Increasing Anticarcinoma Activity of an Anti-erbB2 Recombinant Immunotoxin by the Addition of an Anti-EpCAM sFv Clin. Cancer Res., May 15, 2007; 13(10): 3058 - 3067. [Abstract] [Full Text] [PDF]

				S. Hussain, A. Pluckthun, T. M. Allen, and U. Zangemeister-Wittke Chemosensitization of carcinoma cells using epithelial cell adhesion molecule-targeted liposomal antisense against bcl-2/bcl-xL Mol. Cancer Ther., December 1, 2006; 5(12): 3170 - 3180. [Abstract] [Full Text] [PDF]

				M. S. K. Sutherland, R. J. Sanderson, K. A. Gordon, J. Andreyka, C. G. Cerveny, C. Yu, T. S. Lewis, D. L. Meyer, R. F. Zabinski, S. O. Doronina, et al. Lysosomal Trafficking and Cysteine Protease Metabolism Confer Target-specific Cytotoxicity by Peptide-linked Anti-CD30-Auristatin Conjugates J. Biol. Chem., April 14, 2006; 281(15): 10540 - 10547. [Abstract] [Full Text] [PDF]

				D. Xu and M. E. Hemler Metabolic Activation-related CD147-CD98 Complex Mol. Cell. Proteomics, August 1, 2005; 4(8): 1061 - 1071. [Abstract] [Full Text] [PDF]

				M. Varga, P. Obrist, S. Schneeberger, G. Muhlmann, C. Felgel-Farnholz, D. Fong, M. Zitt, T. Brunhuber, G. Schafer, G. Gastl, et al. Overexpression of Epithelial Cell Adhesion Molecule Antigen in Gallbladder Carcinoma Is an Independent Marker for Poor Survival Clin. Cancer Res., May 1, 2004; 10(9): 3131 - 3136. [Abstract] [Full Text] [PDF]

				M. K. Tur, M. Huhn, T. Thepen, M. Stocker, R. Krohn, S. Vogel, E. Jost, R. Osieka, J. G. van de Winkel, R. Fischer, et al. Recombinant CD64-Specific Single Chain Immunotoxin Exhibits Specific Cytotoxicity against Acute Myeloid Leukemia Cells Cancer Res., December 1, 2003; 63(23): 8414 - 8419. [Abstract] [Full Text] [PDF]