Research ArticleCancer

Genotypic and Histological Evolution of Lung Cancers Acquiring Resistance to EGFR Inhibitors

Science Translational Medicine  23 Mar 2011:
Vol. 3, Issue 75, pp. 75ra26
DOI: 10.1126/scitranslmed.3002003

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The Shifting Sands of Lung Cancer

Lung cancer is the leading cause of death globally and has proven very difficult to treat. The development almost a decade ago of tyrosine kinase inhibitors that specifically block the epidermal growth factor receptor (EGFR), which is switched on in many lung cancers, provided hope that targeted therapies would finally combat this deadly disease. However, only a certain subpopulation of lung cancer patients carrying specific activating mutations in EGFR responded clinically to EGFR inhibitors, and even among these patients, resistance to the inhibitor emerged within 12 months. To better understand how lung cancers develop drug resistance, Sequist and colleagues undertook a comprehensive genetic and histological analysis of 37 patients with non–small cell lung cancer (NSCLC), and they made some surprising discoveries.

In an effort to understand the exact mechanism underscoring the acquisition of drug resistance in NSCLC patients treated with EGFR inhibitors, the investigators analyzed tumor biopsies from patients at the time they acquired resistance. All of the lung cancer patients retained their original activating EGFR mutations, but some patients had acquired another mutation in EGFR (T790M), which interferes with binding of the drug to the receptor, rendering the tumors resistant. Meanwhile, another group of patients became resistant because they developed amplification of a gene encoding the MET tyrosine kinase receptor, which, like EGFR, drives cell growth. Yet other patients acquired drug resistance mechanisms that had not been reported before including amplification of the EGFR gene itself and mutations in the PIK3CA gene (which encodes a subunit of the signaling molecule phosphatidylinositol 3-kinase). In addition, the authors observed that a few lung cancers transitioned from an epithelial cell morphology to a mesenchymal cell–like appearance, which is associated with a more aggressive type of tumor. In five patients, the authors discovered another type of transition that was even more surprising: the conversion of NSCLCs into small cell lung cancers (SCLCs), which are easier to treat. Indeed, these five patients responded well to the typical chemotherapy regimen used to treat SCLCs. To study the evolution of lung tumors in patients over the course of their disease, the investigators took serial biopsies from three lung cancer patients over 2 years. They found that when the patients acquired drug resistance and were then taken off the EGFR inhibitor, they lost the resistance mutations and their tumors once again became sensitive to treatment by either the same or a different EGFR inhibitor. The detailed genetic and histological analysis by Sequist and colleagues provides new insights into the shifting sands of drug resistance evolution in lung cancers and suggests that serial biopsies may be essential in the quest to reverse or even prevent the development of drug resistance.


  • * These authors contributed equally to this work.

  • Citation: L. V. Sequist, B. A. Waltman, D. Dias-Santagata, S. Digumarthy, A. B. Turke, P. Fidias, K. Bergethon, A. T. Shaw, S. Gettinger, A. K. Cosper, S. Akhavanfard, R. S. Heist, J. Temel, J. G. Christensen, J. C. Wain, T. J. Lynch, K. Vernovsky, E. J. Mark, M. Lanuti, A. J. Iafrate, M. Mino-Kenudson, J. A. Engelman, Genotypic and Histological Evolution of Lung Cancers Acquiring Resistance to EGFR Inhibitors. Sci. Transl. Med. 3, 75ra26 (2011).