HER2 Reactivation through Acquisition of the HER2 L755S Mutation as a Mechanism of Acquired Resistance to HER2-targeted Therapy in HER2+ Breast Cancer

Clin Cancer Res. 2017 Sep 1;23(17):5123-5134. doi: 10.1158/1078-0432.CCR-16-2191. Epub 2017 May 9.

Abstract

Purpose: Resistance to anti-HER2 therapies in HER2+ breast cancer can occur through activation of alternative survival pathways or reactivation of the HER signaling network. Here we employed BT474 parental and treatment-resistant cell line models to investigate a mechanism by which HER2+ breast cancer can reactivate the HER network under potent HER2-targeted therapies.Experimental Design: Resistant derivatives to lapatinib (L), trastuzumab (T), or the combination (LR/TR/LTR) were developed independently from two independent estrogen receptor ER+/HER2+ BT474 cell lines (AZ/ATCC). Two derivatives resistant to the lapatinib-containing regimens (BT474/AZ-LR and BT474/ATCC-LTR lines) that showed HER2 reactivation at the time of resistance were subjected to massive parallel sequencing and compared with parental lines. Ectopic expression and mutant-specific siRNA interference were applied to analyze the mutation functionally. In vitro and in vivo experiments were performed to test alternative therapies for mutant HER2 inhibition.Results: Genomic analyses revealed that the HER2L755S mutation was the only common somatic mutation gained in the BT474/AZ-LR and BT474/ATCC-LTR lines. Ectopic expression of HER2L755S induced acquired lapatinib resistance in the BT474/AZ, SK-BR-3, and AU565 parental cell lines. HER2L755S-specific siRNA knockdown reversed the resistance in BT474/AZ-LR and BT474/ATCC-LTR lines. The HER1/2-irreversible inhibitors afatinib and neratinib substantially inhibited both resistant cell growth and the HER2 and downstream AKT/MAPK signaling driven by HER2L755S in vitro and in vivoConclusions: HER2 reactivation through acquisition of the HER2L755S mutation was identified as a mechanism of acquired resistance to lapatinib-containing HER2-targeted therapy in preclinical HER2-amplified breast cancer models, which can be overcome by irreversible HER1/2 inhibitors. Clin Cancer Res; 23(17); 5123-34. ©2017 AACR.

MeSH terms

  • Afatinib
  • Animals
  • Antibodies, Monoclonal, Humanized / administration & dosage
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Drug Resistance, Neoplasm / genetics*
  • Female
  • Humans
  • Lapatinib
  • Mice
  • Molecular Targeted Therapy*
  • Mutation
  • Quinazolines / administration & dosage
  • Quinazolines / adverse effects
  • Receptor, ErbB-2 / antagonists & inhibitors
  • Receptor, ErbB-2 / genetics*
  • Receptors, Estrogen / genetics
  • Signal Transduction / drug effects
  • Trastuzumab / administration & dosage
  • Trastuzumab / adverse effects
  • Xenograft Model Antitumor Assays

Substances

  • Antibodies, Monoclonal, Humanized
  • Quinazolines
  • Receptors, Estrogen
  • Lapatinib
  • Afatinib
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • Trastuzumab