Efficacy and Determinants of Response to HER Kinase Inhibition in HER2-Mutant Metastatic Breast Cancer

Cancer Discov. 2020 Feb;10(2):198-213. doi: 10.1158/2159-8290.CD-19-0966. Epub 2019 Dec 5.


HER2 mutations define a subset of metastatic breast cancers with a unique mechanism of oncogenic addiction to HER2 signaling. We explored activity of the irreversible pan-HER kinase inhibitor neratinib, alone or with fulvestrant, in 81 patients with HER2-mutant metastatic breast cancer. Overall response rate was similar with or without estrogen receptor (ER) blockade. By comparison, progression-free survival and duration of response appeared longer in ER+ patients receiving combination therapy, although the study was not designed for direct comparison. Preexistent concurrent activating HER2 or HER3 alterations were associated with poor treatment outcome. Similarly, acquisition of multiple HER2-activating events, as well as gatekeeper alterations, were observed at disease progression in a high proportion of patients deriving clinical benefit from neratinib. Collectively, these data define HER2 mutations as a therapeutic target in breast cancer and suggest that coexistence of additional HER signaling alterations may promote both de novo and acquired resistance to neratinib. SIGNIFICANCE: HER2 mutations define a targetable breast cancer subset, although sensitivity to irreversible HER kinase inhibition appears to be modified by the presence of concurrent activating genomic events in the pathway. These findings have implications for potential future combinatorial approaches and broader therapeutic development for this genomically defined subset of breast cancer.This article is highlighted in the In This Issue feature, p. 161.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / pathology
  • Breast Neoplasms, Male / drug therapy*
  • Breast Neoplasms, Male / genetics
  • Breast Neoplasms, Male / pathology
  • Cell Line, Tumor
  • DNA Mutational Analysis
  • Drug Resistance, Neoplasm / drug effects
  • Drug Resistance, Neoplasm / genetics
  • Drug Synergism
  • Estrogen Receptor Antagonists / pharmacology
  • Estrogen Receptor Antagonists / therapeutic use
  • Female
  • Fulvestrant / pharmacology
  • Fulvestrant / therapeutic use
  • Humans
  • Male
  • Middle Aged
  • Mutation
  • Prospective Studies
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Quinolines / pharmacology
  • Quinolines / therapeutic use
  • Receptor, ErbB-2 / antagonists & inhibitors*
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / metabolism
  • Receptors, Estrogen / antagonists & inhibitors*
  • Receptors, Estrogen / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Treatment Outcome


  • Estrogen Receptor Antagonists
  • Protein Kinase Inhibitors
  • Quinolines
  • Receptors, Estrogen
  • Fulvestrant
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • neratinib