The epidermal growth factor receptor-L861Q mutation increases kinase activity without leading to enhanced sensitivity toward epidermal growth factor receptor kinase inhibitors.
BACKGROUND
Mutations in the epidermal growth factor receptor (EGFR) kinase domain such as EGFR-L858R and EGFR-G719S have been reported to activate the kinase and also sensitize a subset of patients with non-small cell lung cancer to EGFR kinase inhibitor treatment. Nevertheless, for other common point mutations such as EGFR-L861Q, it is unclear whether and to what extent they sensitize toward gefitinib and erlotinib. Thus far, there is no reliable cellular assay to compare in a ligand-independent manner intrinsic kinase activity and drug sensitivity of the unmutated (wild type) and mutated EGFR kinase domain.


METHODS
To overcome this obstacle, we introduced L858R, G719S, and L861Q into the backbone of EGFRvIII. EGFRvIII has a wild type-kinase domain but is activated in a ligand-independent manner through a deletion in the extracellular domain.


RESULTS
Using this tool, we show that the L861Q mutation displays enhanced kinase activity and transforming potential compared with L858R, G719S, and also to the wild type-EGFR kinase domain. Interestingly, L861Q does not increase drug sensitivity toward clinically used EGFR kinase inhibitors in contrast to the L858R and G719S mutation. In addition, we demonstrate that EGFR-L861Q could be effectively inhibited with the irreversible second-generation EGFR inhibitor WZ-4002.


CONCLUSIONS
Thus, in the common EGFR-L861Q mutation, activation of the kinase domain is uncoupled from a sensitizing effect toward clinically approved kinase inhibitors. Therefore, patients with EGFR-L861Q may not have the same clinical benefit from gefitinib/erlotinib treatment as patients with EGFR-L858R and EGFR-G719S mutations. Treatment with irreversible second-generation kinase inhibitors such as WZ-4002 may be an attractive option in the future for patients with EGFR-L861Q.
Department of Internal Medicine III, Technical University of Munich, Munich, Germany.
Rama Krishna
RK
Kancha
Christian
C
Peschel
Justus
J
Duyster
D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D000077156:Gefitinib; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics*; D054448:Precursor Cells, B-Lymphoid / Q000187:drug effects / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology
D047428:Protein Kinase Inhibitors; D011799:Quinazolines; C410723:epidermal growth factor receptor VIII; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; D000077156:Gefitinib