An ERBB1-3 Neutralizing Antibody Mixture With High Activity Against Drug-Resistant HER2+ Breast Cancers With ERBB Ligand Overexpression

J Natl Cancer Inst. 2017 Nov 1;109(11):djx065. doi: 10.1093/jnci/djx065.


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: HER2+ 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 HER2+ 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 mm 3 , SD = 924 mm 3 , vs Pan-HER mean = 565 mm 3 , SD = 499 mm 3 , 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 HER2+ breast cancers progressing after T-DM1 and trastuzumab (NRG1 transcript fold change ± 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 HER2+ cancers.

MeSH terms

  • Ado-Trastuzumab Emtansine
  • Animals
  • Antibodies, Monoclonal, Humanized / therapeutic use
  • Antibodies, Neutralizing / therapeutic use*
  • Antineoplastic Agents / therapeutic use*
  • Breast Neoplasms / chemistry
  • Breast Neoplasms / drug therapy*
  • Cell Line, Tumor
  • Drug Resistance, Neoplasm
  • ErbB Receptors / antagonists & inhibitors
  • Female
  • Humans
  • Lapatinib
  • Ligands
  • Maytansine / analogs & derivatives
  • Maytansine / therapeutic use
  • Mice
  • Mice, Nude
  • Quinazolines / therapeutic use
  • Receptor, ErbB-2 / antagonists & inhibitors
  • Receptor, ErbB-3 / antagonists & inhibitors
  • Trastuzumab / therapeutic use
  • Xenograft Model Antitumor Assays


  • Antibodies, Monoclonal, Humanized
  • Antibodies, Neutralizing
  • Antineoplastic Agents
  • Ligands
  • Quinazolines
  • Lapatinib
  • Maytansine
  • ERBB2 protein, human
  • ERBB3 protein, human
  • ErbB Receptors
  • Receptor, ErbB-2
  • Receptor, ErbB-3
  • pertuzumab
  • Trastuzumab
  • Ado-Trastuzumab Emtansine