title: Bispecific Antibodies and Antibody-Drug Conjugates (ADCs) Bridging HER2 and Prolactin Receptor Improve Efficacy of HER2 ADCs.
abstract: The properties of cell surface proteins targeted by antibody-drug conjugates (ADCs) have not been fully exploited; of particular importance are the rate of internalization and the route of intracellular trafficking. In this study, we compared the trafficking of HER2, which is the target of the clinically approved ADC ado-trastuzumab emtansine (T-DM1), with that of prolactin receptor (PRLR), another potential target in breast cancer. In contrast to HER2, we found that PRLR is rapidly and constitutively internalized, and traffics efficiently to lysosomes, where it is degraded. The PRLR cytoplasmic domain is necessary to promote rapid internalization and degradation, and when transferred to HER2, enhances HER2 degradation. In accordance with these findings, low levels of cell surface PRLR (∼30,000 surface receptors per cell) are sufficient to mediate effective killing by PRLR ADC, whereas cell killing by HER2 ADC requires higher levels of cell surface HER2 (∼106surface receptors per cell). Noncovalently cross-linking HER2 to PRLR at the cell surface, using a bispecific antibody that binds to both receptors, dramatically enhances the degradation of HER2 as well as the cell killing activity of a noncompeting HER2 ADC. Furthermore, in breast cancer cells that coexpress HER2 and PRLR, a HER2xPRLR bispecific ADC kills more effectively than HER2 ADC. These results emphasize that intracellular trafficking of ADC targets is a key property for their activity and, further, that coupling an ADC target to a rapidly internalizing protein may be a useful approach to enhance internalization and cell killing activity of ADCs.Mol Cancer Ther; 16(4); 681-93. ©2017 AACR.
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York. julian.andreev@regeneron.com.
authors.forename: Julian
authors.initials: J
authors.lastname: Andreev
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Nithya
authors.initials: N
authors.lastname: Thambi
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Andres E
authors.initials: AE
authors.lastname: Perez Bay
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Frank
authors.initials: F
authors.lastname: Delfino
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Joel
authors.initials: J
authors.lastname: Martin
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Marcus P
authors.initials: MP
authors.lastname: Kelly
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Kirshner
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Ashique
authors.initials: A
authors.lastname: Rafique
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Arthur
authors.initials: A
authors.lastname: Kunz
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nittoli
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Douglas
authors.initials: D
authors.lastname: MacDonald
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Christopher
authors.initials: C
authors.lastname: Daly
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: William
authors.initials: W
authors.lastname: Olson
authors.affiliation: Regeneron Pharmaceuticals, Tarrytown, New York.
authors.forename: Gavin
authors.initials: G
authors.lastname: Thurston
mesh_terms: D000080044:Ado-Trastuzumab Emtansine; D018033:Antibodies, Bispecific / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000494:pharmacology*; D008453:Maytansine / Q000031:analogs & derivatives* / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011981:Receptors, Prolactin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000068878:Trastuzumab
chemical_list: D000080044:Ado-Trastuzumab Emtansine; D018033:Antibodies, Bispecific; D061067:Antibodies, Monoclonal, Humanized; D018796:Immunoconjugates; D008453:Maytansine; D018719:Erb-b2 Receptor Tyrosine Kinases; D011981:Receptors, Prolactin; D000068878:Trastuzumab; C508053:ERBB2 protein, human