title: Enhanced tumor-targeting selectivity by modulating bispecific antibody binding affinity and format valence.
abstract: Bispecific antibodies are considered attractive bio-therapeutic agents owing to their ability to target two distinct disease mediators. Cross-arm avidity targeting of antigen double-positive cancer cells over single-positive normal tissue is believed to enhance the therapeutic efficacy, restrict major escape mechanisms and increase tumor-targeting selectivity, leading to reduced systemic toxicity and improved therapeutic index. However, the interplay of factors regulating target selectivity is not well understood and often overlooked when developing clinically relevant bispecific therapeutics. We show in vivo that dual targeting alone is not sufficient to endow selective tumor-targeting, and report the pivotal roles played by the affinity of the individual arms, overall avidity and format valence. Specifically, a series of monovalent and bivalent bispecific IgGs composed of the anti-HER2 trastuzumab moiety paired with affinity-modulated VHand VLregions of the anti-EGFR GA201 mAb were tested for selective targeting and eradication of double-positive human NCI-H358 non-small cell lung cancer target tumors over single-positive, non-target NCI-H358-HER2 CRISPR knock out tumors in nude mice bearing dual-flank tumor xenografts. Affinity-reduced monovalent bispecific variants, but not their bivalent bispecific counterparts, mediated a greater degree of tumor targeting selectivity, while the overall efficacy against the targeted tumor was not substantially affected.
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA.
authors.forename: Yariv
authors.initials: Y
authors.lastname: Mazor
authors.affiliation: Department of Oncology, MedImmune, Gaithersburg, MD, USA.
authors.forename: Kris F
authors.initials: KF
authors.lastname: Sachsenmeier
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA.
authors.forename: Chunning
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Respiratory, Inflammation and Autoimmunity, MedImmune, Gaithersburg, MD, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Hansen
authors.affiliation: Department of Oncology, MedImmune, Gaithersburg, MD, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Filderman
authors.affiliation: Department of Oncology, MedImmune, Gaithersburg, MD, USA.
authors.forename: Kathy
authors.initials: K
authors.lastname: Mulgrew
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA.
authors.forename: Herren
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Dall'Acqua
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000008:administration & dosage / Q000276:immunology*; D000915:Antibody Affinity; D000918:Antibody Specificity; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000276:immunology*; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000276:immunology; D006801:Humans; D008819:Mice, Nude; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology; D000068878:Trastuzumab / Q000008:administration & dosage / Q000276:immunology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D018033:Antibodies, Bispecific; D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C512478:EGFR protein, human; C508053:ERBB2 protein, human