Structural and mechanistic underpinnings of the differential drug sensitivity of EGFR mutations in non-small cell lung cancer.
EGFR and other ErbB-family tyrosine kinases are overexpressed in many human tumors, and their aberrant expression and mutational activation is associated with the development, progression and aggressiveness of a number of malignancies. Thus the EGFR kinase has long been recognized as a potential drug target in oncology, and small-molecule inhibitors have been under development for more than two decades. As a result of their effectiveness in treating non-small cell lung cancers (NSCLCs) driven by somatic mutations in the EGFR kinase, gefitinib and erlotinib were the first EGFR tyrosine kinase inhibitors (TKIs) approved for clinical use. Ironically, these drugs found their target against mutant forms of the EGFR kinase, which have altered enzyme active sites, and not against the wild type (WT) kinase against which their potency and selectivity was carefully honed. Here we review recent structural and enzymological studies that explore the exquisite sensitivity of a subset of these lung cancer mutants to gefitinib and erlotinib. We discuss available structural evidence for the mechanisms of activation of the EGFR kinase by these mutants, and compare it to physiologic activation of the kinase by ligand-induced dimerization. Finally, we consider the mechanisms by which the secondary T790M "gatekeeper" mutation confers resistance to gefitinib and erlotinib.
Eck
Michael J
MJ
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and Department of Cancer Biology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA. eck@red.dfci.harvard.edu
Yun
Cai-Hong
CH
D000818:Animals; D020134:Catalytic Domain / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D066246:ErbB Receptors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000069347:Erlotinib Hydrochloride; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D009154:Mutation; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000627:therapeutic use; D017434:Protein Structure, Tertiary / Q000235:genetics; D011799:Quinazolines / Q000737:chemistry* / Q000627:therapeutic use; D055752:Small Cell Lung Carcinoma / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D013329:Structure-Activity Relationship
D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib