title: Strongly enhanced antitumor activity of trastuzumab and pertuzumab combination treatment on HER2-positive human xenograft tumor models.
abstract: The human epidermal growth factor receptor (HER) family plays an important role in cell survival and proliferation, and is implicated in oncogenesis. Overexpression of HER2 is associated with aggressive disease and poor prognosis. Trastuzumab is a humanized monoclonal antibody targeting HER2 and has proven survival benefit for women with HER2-positive early and metastatic breast cancer. Pertuzumab, another monoclonal antibody, is a HER2 dimerization inhibitor that binds to a different epitope on HER2 than trastuzumab and inhibits HER2 dimer formation with other HER family members such as HER3 and HER1. We investigated the antitumor activity of these agents alone and in combination in HER2-positive breast and non-small cell lung cancer xenografts. Our data show that the combination of trastuzumab and pertuzumab has a strongly enhanced antitumor effect and induces tumor regression in both xenograft models, something that cannot be achieved by either monotherapy. The enhanced efficacy of the combination was also observed after tumor progression during trastuzumab monotherapy. Near-IR fluorescence imaging experiments confirm that pertuzumab binding to tumors is not impaired by trastuzumab pretreatment. Furthermore, we show by in vitro assay that both trastuzumab and pertuzumab potently activate antibody-dependent cellular cytotoxicity. However, our data suggest that the strongly enhanced antitumor activity is mainly due to the differing but complementary mechanisms of action of trastuzumab and pertuzumab, namely inhibition of HER2 dimerization and prevention of p95HER2 formation.
authors.affiliation: Roche Diagnostics GmbH, Pharma Research Penzberg, Penzberg, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Scheuer
authors.forename: Thomas
authors.initials: T
authors.lastname: Friess
authors.forename: Helmut
authors.initials: H
authors.lastname: Burtscher
authors.forename: Birgit
authors.initials: B
authors.lastname: Bossenmaier
authors.forename: Josef
authors.initials: J
authors.lastname: Endl
authors.forename: Max
authors.initials: M
authors.lastname: Hasmann
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D004357:Drug Synergism; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D034741:RNA, Small Interfering / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*; D020893:Receptor, ErbB-3 / Q000096:biosynthesis / Q000235:genetics; D000068878:Trastuzumab; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D066246:ErbB Receptors; D034741:RNA, Small Interfering; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D000068878:Trastuzumab; C512478:EGFR protein, human; C485206:pertuzumab