1. Characterization of a CC49-Based Single-Chain Fragment−β-Lactamase Fusion Protein for Antibody-Directed Enzyme Prodrug Therapy (ADEPT)
- Author
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Joshua Roy Basler, Lilia Babé, Peter D. Senter, Volker Schellenberger, Enrique Escandon, Ralph F. Alderson, Martin Roberge, Wei Geng, Brian E. Toki, Regina Chin, Roanna Ueda, Judith A. Fox, Tianling Chen, Amy Liu, Tessi Kanavarioti, and Douglas Hodges
- Subjects
Antibodies, Neoplasm ,Recombinant Fusion Proteins ,Cell ,Immunoglobulin Variable Region ,Biomedical Engineering ,Mice, Nude ,Pharmaceutical Science ,Mutagenesis (molecular biology technique) ,Bioengineering ,Irinotecan ,beta-Lactamases ,Epitope ,Mice ,Drug Delivery Systems ,medicine ,Animals ,Humans ,Prodrugs ,Antineoplastic Agents, Alkylating ,Immunoglobulin Fragments ,Melphalan ,Binding selectivity ,Pharmacology ,Drug Carriers ,Antibiotics, Antineoplastic ,Molecular Structure ,biology ,Chemistry ,Organic Chemistry ,Adept ,Prodrug ,Antineoplastic Agents, Phytogenic ,Fusion protein ,Molecular biology ,Cephalosporins ,medicine.anatomical_structure ,Biochemistry ,Doxorubicin ,Nitrogen Mustard Compounds ,biology.protein ,Camptothecin ,Female ,Antibody ,Colorectal Neoplasms ,Neoplasm Transplantation ,Biotechnology - Abstract
CC49 is a clinically validated antibody with specificity for TAG-72, a carbohydrate epitope that is overexpressed and exposed on the cell surface in a large fraction of solid malignancies. We constructed a single-chain fragment (scFv) based on CC49 and fused it to beta-lactamase (BLA). Following optimization of the scFv domain by combinatorial consensus mutagenesis (CCM) for increased expression and stability, we characterized the protein variant for binding, in vivo pharmacokinetics (PK), and antitumor efficacy. The fusion protein TAB2.5 possessed a similar binding specificity relative to the parent antibody CC49. TAB2.5 also showed prolonged retention (T(1/2) = 36.9 h) in tumor-bearing mice with tumor/plasma ratios of up to 1000. Preliminary evaluation of TAB2.5, in combination with a novel prodrug, GC-Mel, resulted in significant efficacy in a colorectal xenograft tumor model and supports the utility of the protein as an agent for tumor-selective prodrug activation.
- Published
- 2006
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