An ERBB1-3 Neutralizing Antibody Mixture With High Activity Against Drug-Resistant HER21 Breast Cancers With ERBB Ligand Overexpression

Luis J. Schwarz, Katherine E. Hutchinson, Brent N. Rexer, Mónica Valeria Estrada, Paula I. Gonzalez Ericsson, Melinda E. Sanders, Teresa C. Dugger, Luigi Formisano, Angel Guerrero-Zotano, Monica Red-Brewer, Christian D. Young, Johan Lantto, Mikkel W. Pedersen, Michael Kragh, Ivan D. Horak, Carlos L. Arteaga

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Background: Plasticity of the ERBB receptor network has been suggested to cause acquired resistance to anti–human epidermal growth factor receptor 2 (HER2) therapies. Thus, we studied whether a novel approach using an ERBB1-3-neutralizing antibody mixture can block these compensatory mechanisms of resistance. Methods: HER2þ cell lines and xenografts (n ≥ 6 mice per group) were treated with the ERBB1-3 antibody mixture Pan-HER, trastuzumab/lapatinib (TL), trastuzumab/pertuzumab (TP), or T-DM1. Downregulation of ERBB receptors was assessed by immunoblot analysis and immunohistochemistry. Paired pre- and post-T-DM1 tumor biopsies from patients (n = 11) with HER2-amplified breast cancer were evaluated for HER2 and P-HER3 expression by immunohistochemistry and/or fluorescence in situ hybridization. ERBB ligands were measured by quantitative reverse transcription polymerase chain reaction. Drug-resistant cells were generated by chronic treatment with T-DM1. All statistical tests were two-sided. Results: Treatment with Pan-HER inhibited growth and promoted degradation of ERBB1-3 receptors in a panel of HER2þ breast cancer cells. Compared with TL, TP, and T-DM1, Pan-HER induced a similar antitumor effect against established BT474 and HCC1954 tumors, but was superior to TL against MDA-361 xenografts (TL mean = 2026 mm3, SD = 924 mm3, vs Pan-HER mean = 565 mm3, SD = 499 mm3, P = .04). Pan-HER-treated BT474 xenografts did not recur after treatment discontinuation, whereas tumors treated with TL, TP, and T-DM1 did. Post-TP and post-T-DM1 recurrent tumors expressed higher levels of neuregulin-1 (NRG1), HER3 and P-HER3 (all P < .05). Higher levels of P-HER3 protein and NRG1 mRNA were also observed in HER2þ breast cancers progressing after T-DM1 and trastuzumab (NRG1 transcript fold change 6 SD; pretreatment = 2, SD = 1.9, vs post-treatment = 11.4, SD = 10.3, P = .04). The HER3-neutralizing antibody LJM716 resensitized the drug-resistant cells to T-DM1, suggesting a causal association between the NRG1-HER3 axis and drug resistance. Finally, Pan-HER treatment inhibited growth of HR6 trastuzumab- and T-DM1-resistant xenografts. Conclusions: These data suggest that upregulation of a NRG1-HER3 axis can mediate escape from anti-HER2 therapies. Further, multitargeted antibody mixtures, such as Pan-HER, can simultaneously remove and/or block targeted ERBB receptor and ligands, thus representing an effective approach against drug-sensitive and -resistant HER2þ cancers.

Original languageEnglish (US)
Article numberdjx065
JournalJournal of the National Cancer Institute
Issue number11
StatePublished - Nov 1 2017

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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