Predictive impact of low-frequency pretreatment T790M mutation in patients with EGFR-mutated non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors

Lung Cancer. 2020 Jan:139:80-88. doi: 10.1016/j.lungcan.2019.10.029. Epub 2019 Nov 2.

Abstract

Objectives: Low-frequency epidermal growth factor receptor (EGFR) T790M mutation could be detected by ultrasensitive methods in EGFR tyrosine kinase inhibitor (TKI)-naïve non-small cell lung cancer (NSCLC). However, the impact of pretreatment T790M (preT790M) on the efficacy of EGFR-TKIs and on resistance remains unclear.

Materials and methods: Two independent cohorts consisting of advanced EGFR-mutated NSCLC patients treated with first-line EGFR-TKIs, a derivation cohort that started treatment between August 2013 and July 2016 (cohort A, n = 44) and a validation cohort between August 2016 and December 2017 (cohort B, n = 22), were examined in this study. Among these, 28 patients underwent re-biopsy at disease progression. DNAs from pretreatment tumor biopsy samples and re-biopsy samples were assessed to detect T790M by the Cobas EGFR Mutation Test v2 (Cobas) and for quantitating T790M by droplet digital polymerase chain reaction (ddPCR).

Results: Detection rates of preT790M were 40.9% (18/44) in cohort A and 45.5% (10/22) in cohort B by ddPCR, and none by Cobas. A cutoff value of 0.3% for dividing into high- vs. low-preT790M allele frequency was determined by receiver operating characteristic curve analysis in cohort A. Progression-free survival (PFS) was significantly shorter in the high- preT790M group (n = 12) than in the low-preT790M (n = 6) and negative (n = 26) groups (combined low-preT790M) (median: 6.9 vs. 13.8 months, P = 0.00073). These observations were validated in cohort B [median: 6.2 (n = 5) vs. 15.3 months (n = 17), P = 0.0029]. In 28 paired biopsies, Cobas detected post-progression T790M in 60% (3/5) of the high-preT790M, in 57% (4/7) of the low-preT790M, and in 56% (9/16) of the negative-preT790M groups.

Conclusion: EGFR-mutated NSCLC with high preT790M had significantly shorter PFS on EGFR-TKIs. However, preT790M abundance may not necessarily confer post-TKI T790M resistance.

Keywords: Droplet digital polymerase chain reaction; Epidermal growth factor receptor; Non-small cell lung cancer; Pretreatment T790M.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Non-Small-Cell Lung / drug therapy
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / pathology*
  • ErbB Receptors / genetics
  • Female
  • Follow-Up Studies
  • Humans
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology*
  • Male
  • Middle Aged
  • Mutation Rate
  • Mutation*
  • Prognosis
  • Protein Kinase Inhibitors / therapeutic use*
  • Retrospective Studies
  • Survival Rate

Substances

  • Protein Kinase Inhibitors
  • EGFR protein, human
  • ErbB Receptors