EGFR genetic heterogeneity of nonsmall cell lung cancers contributing to acquired gefitinib resistance

Int J Cancer. 2008 Dec 1;123(11):2480-6. doi: 10.1002/ijc.23868.


Gefitinib is dramatically effective for nonsmall cell lung cancers (NSCLCs) with activating mutations of the epidermal growth factor receptor (EGFR) gene, but these tumors eventually develop drug resistance, attributable to a secondary T790M mutation or acquired MET amplification in some relapsed tumors. We analyzed EGFR mutations in matched pre- and post-therapeutic tumors of 6 gefitinib-responding lung cancers. With conventional PCR-based sequencing, classic mutations were detected in pretreatment samples of each case. The same mutations were readily confirmed in treated lesions of 4 cases, but were absent in those of Cases 1 and 2. Subsequent mutant-enriched peptide-nucleic-acid-mediated PCR clamping and subcloning assays detected the mutation in minor cells of treated lesions of Case 1, but still failed to detect a mutation in Case 2. We thus performed microdissection-based cell cluster mutation analysis of pretreatment tumors, and found that 3, including the first 2, concurrently contained tumor cells with either mutant or wild-type EGFR, although the latter was only a minor fraction. These findings suggest that some NSCLCs are genetically heterogeneous with regard to EGFR mutations; gefitinib-sensitive mutants decrease or vanish while wild clones selectively survive with gefitinib treatment. In addition, T790M was detected in a small fraction of treated lesions of 3 cases, and MET amplification was revealed in 3 treated tumors of Case 2. Thus, our results suggest that multiple mechanisms underlie acquired gefitinib resistance, and selection on a background of EGFR genetic heterogeneity also contributes to acquisition of resistance in a proportion of NSCLCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Base Sequence
  • Carcinoma, Non-Small-Cell Lung / drug therapy
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / metabolism*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Drug Resistance, Neoplasm / drug effects*
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • Exons / genetics
  • Female
  • Gefitinib
  • Genetic Heterogeneity*
  • Humans
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Mutation / genetics
  • Quinazolines / therapeutic use*


  • Quinazolines
  • ErbB Receptors
  • Gefitinib