title: High throughput cytotoxicity screening of anti-HER2 immunotoxins conjugated with antibody fragments from phage-displayed synthetic antibody libraries.
abstract: Immunotoxins are an important class of antibody-based therapeutics. The potency of the immunotoxins depends on the antibody fragments as the guiding modules targeting designated molecules on cell surfaces. Phage-displayed synthetic antibody scFv libraries provide abundant antibody fragment candidates as targeting modules for the immunoconjugates, but the discovery of optimally functional immunoconjugates is limited by the scFv-payload conjugation procedure. In this work, cytotoxicity screening of non-covalently assembled immunotoxins was developed in high throughput format to discover highly functional synthetic antibody fragments for delivering toxin payloads. The principles governing the efficiency of the antibodies as targeting modules have been elucidated from large volume of cytotoxicity data: (a) epitope and paratope of the antibody-based targeting module are major determinants for the potency of the immunotoxins; (b) immunotoxins with bivalent antibody-based targeting modules are generally superior in cytotoxic potency to those with corresponding monovalent targeting module; and (c) the potency of the immunotoxins is positively correlated with the densities of the cell surface antigen. These findings suggest that screening against the target cells with a large pool of antibodies from synthetic antibody libraries without the limitations of natural antibody responses can lead to optimal potency and minimal off-target toxicity of the immunoconjugates.
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Shin-Chen
authors.initials: SC
authors.lastname: Hou
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Hong-Sen
authors.initials: HS
authors.lastname: Chen
authors.affiliation: Department of Life Science, Tunghai University, Taichung 407, Taiwan.
authors.forename: Hung-Wei
authors.initials: HW
authors.lastname: Lin
authors.affiliation: Department of Life Science, Tunghai University, Taichung 407, Taiwan.
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Chao
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Yao-Sheng
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Chi-Yu
authors.initials: CY
authors.lastname: Fu
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Yu
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Kai-Fa
authors.initials: KF
authors.lastname: Huang
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Andrew H-J
authors.initials: AH
authors.lastname: Wang
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei 115, Taiwan.
authors.forename: An-Suei
authors.initials: AS
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D000915:Antibody Affinity / Q000276:immunology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D057809:HEK293 Cells; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology; D000922:Immunotoxins / Q000737:chemistry / Q000276:immunology*; D061986:MCF-7 Cells; D019151:Peptide Library; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
chemical_list: D000939:Epitopes; D018796:Immunoconjugates; D000922:Immunotoxins; D019151:Peptide Library; D018719:Erb-b2 Receptor Tyrosine Kinases; D057127:Single-Chain Antibodies