title: A new bispecific antibody targeting non-overlapping epitopes on IGF2: design, in vitro characterization and pharmacokinetics in macaques.
abstract: The insulin-like growth factor 2 (IGF2) is an important target for cancer therapy. We have previously proposed an approach for fast and irreversible removal of IGF2 from the circulation by using monoclonal antibodies (mAbs) that bind to two or more non-overlapping epitopes on the same molecule. We provided initial evidence for the formation of oligomeric antibody-ligand complexes that can bind to cells expressing Fc gamma receptors (FcγRs) with high avidity using an antibody domain with relatively low affinity as one of the anti-IGF2 mAbs. Recently, we identified a mAb, m708.5, in a scFv format which binds to both IGF2 and IGF1 with very high (pM) affinity. Interestingly, and rather surprisingly, this mAb did not compete with our other high affinity mAb, m610.27, for binding to IGF2. Therefore, we generated a new bispecific mAb, m67, by combining m708.5 and m610.27. As expected m67 potently inhibited binding of IGF2 to cells expressing the IGF1R and its phosphorylation, and resulted in formation of multimolecular complexes when incubated with IGF2 and bound with high avidity to cells expressing FcγRII; the complexes were internalized in a macrophage-like cell line. However, although m67 exhibited a reasonably long half-life (6.4 ± 0.6 days) in cynomolgus macaques and high stability in serum, its administration to three animals did not result in any measurable decrease in the IGF2 concentration likely due to the complexity of the IGF2 interactions in the blood and the relatively low (2mg/kg) dose of the mAb leading to a relatively low maximal blood concentration of 120nM. In spite of the lack of effect on the IGF2 concentration in this particular experimental setup, m67 exhibited good drugability properties and could be highly effective in other animal models and in humans. Studies with animal models of cancer are ongoing to evaluate the potential of m67 as a new candidate mAb-based therapeutic.
authors.affiliation: Protein Interactions Group, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States. Electronic address: fengya@mail.nih.gov.
authors.forename: Yang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Guangdong 518000, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Protein Interactions Group, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States.
authors.forename: Weizao
authors.initials: W
authors.lastname: Chen
authors.affiliation: Protein Interactions Group, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States; Geneva Foundation, 917 Pacific Ave, Suite 600, Tacoma, WA 98402, United States.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: SNBL USA, 6605 Merrill Creek Parkway, Everett, WA 98203, United States.
authors.forename: Karalyne
authors.initials: K
authors.lastname: Crowder
authors.affiliation: Protein Interactions Group, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, United States.
authors.forename: Dimiter S
authors.initials: DS
authors.lastname: Dimitrov
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology / Q000493:pharmacokinetics*; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000493:pharmacokinetics*; D000918:Antibody Specificity / Q000276:immunology*; D000970:Antineoplastic Agents / Q000276:immunology / Q000493:pharmacokinetics*; D015195:Drug Design; D004355:Drug Stability; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000037:antagonists & inhibitors* / Q000276:immunology; D061986:MCF-7 Cells; D008252:Macaca fascicularis
chemical_list: D018033:Antibodies, Bispecific; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D000939:Epitopes; D018985:Epitopes, B-Lymphocyte; D007335:Insulin-Like Growth Factor II
keywords: Bispecific antibodies; Cynomolgus macaques; Half-life; IGF ligand