Mechanisms of acquired resistance to afatinib clarified with liquid biopsy

PLoS One. 2018 Dec 14;13(12):e0209384. doi: 10.1371/journal.pone.0209384. eCollection 2018.


Although mechanisms of acquired resistance to 1st and 3rd generation EGFR-TKI continue to be elucidated, there have been few clinical investigations into the mechanisms of acquired resistance to the 2nd generation EGFR-TKI afatinib. We analyzed data from 20 patients with advanced lung adenocarcinoma who acquired resistance to afatinib, including resistance during EGFR-TKI re-challenge. We examined EGFR T790M and C797S mutations, BRAF V600E mutation, and MET amplification with the MBP-QP method and with droplet digital PCR using ctDNA and re-biopsy samples obtained before and after afatinib treatment. Just before afatinib treatment, 15 of the 20 patients were T790M negative and five were positive. Among the T790M negative patients, 40.0% (6/15) became positive at the time of PD under afatinib. In patients positive for T790M, changes in T790M allele frequency were correlated with afatinib treatment efficacy. C797S was not detected in any patients just before afatinib treatment, but it appeared after treatment in three patients, although with very low allele frequency. Two of these three patients, although positive for both C797S and T790M, achieved PR to osimertinib. However, PFS of these patients was somewhat shorter than that of patients positive for T790M only. BRAF V600E was detected in one patient at PD under afatinib. MET amplification was not detected in this study. T790M is associated with acquired resistance to afatinib, as with 1st generation EGFR-TKI, but with somewhat lower frequency. The influence of C797S on resistance to afatinib is less than that of T790M, but C797S might cause shorter PFS under osimertinib.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylamides
  • Adenocarcinoma of Lung / blood
  • Adenocarcinoma of Lung / drug therapy
  • Adenocarcinoma of Lung / genetics
  • Adenocarcinoma of Lung / mortality
  • Adult
  • Afatinib / pharmacology*
  • Afatinib / therapeutic use
  • Aged
  • Aged, 80 and over
  • Aniline Compounds
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Circulating Tumor DNA / genetics
  • Circulating Tumor DNA / isolation & purification
  • Drug Resistance, Neoplasm / genetics*
  • ErbB Receptors / antagonists & inhibitors
  • ErbB Receptors / genetics
  • Female
  • Gene Frequency
  • Humans
  • Liquid Biopsy
  • Lung Neoplasms / blood
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / mortality
  • Male
  • Middle Aged
  • Mutation
  • Piperazines / pharmacology
  • Piperazines / therapeutic use
  • Polymerase Chain Reaction
  • Progression-Free Survival
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinase Inhibitors / therapeutic use


  • Acrylamides
  • Aniline Compounds
  • Antineoplastic Agents
  • Circulating Tumor DNA
  • Piperazines
  • Protein Kinase Inhibitors
  • osimertinib
  • Afatinib
  • EGFR protein, human
  • ErbB Receptors

Grants and funding

TN received funding support. This work was supported in part (data analysis) by Grants-in Aid for Cancer Research: Special Cancer Research, from the Ministry of Education, Culture, Science, and Technology, Japan (grant number JP17K07197). ARKRAY Inc. provided support in the form of salaries for authors KK and MH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.