EGFR Exon 18 Mutations in Lung Cancer: Molecular Predictors of Augmented Sensitivity to Afatinib or Neratinib as Compared with First- or Third-Generation TKIs

by Selleckchem | Feb 05 2017

PURPOSE:

Lung cancers harboring common EGFR mutations respond to EGFR tyrosine kinase inhibitors (TKI), whereas exon 20 insertions (Ins20) are resistant to them. However, little is known about mutations in exon 18.

EXPERIMENTAL DESIGN:

Mutational status of lung cancers between 2001 and 2015 was reviewed. Three representative mutations in exon 18, G719A, E709K, and exon 18 deletion (Del18: delE709_T710insD) were retrovirally introduced into Ba/F3 and NIH/3T3 cells. The 90% inhibitory concentrations (IC90s) of first-generation (1G; gefitinib and erlotinib), second-generation (2G; afatinib, dacomitinib, and neratinib), and third-generation TKIs (3G; AZD9291 and CO1686) were determined.

RESULTS:

Among 1,402 EGFR mutations, Del19, L858R, and Ins20 were detected in 40%, 47%, and 4%, respectively. Exon 18 mutations, including G719X, E709X, and Del18, were present in 3.2%. Transfected Ba/F3 cells grew in the absence of IL3, and NIH/3T3 cells formed foci with marked pile-up, indicating their oncogenic abilities. IC90s of 1G and 3G TKIs in G719A, E709K, and Del18 were much higher than those in Del19 (by >11-50-fold), whereas IC90s of afatinib were only 3- to 7-fold greater than those for Del19. Notably, cells transfected with G719A and E709K exhibited higher sensitivity to neratinib (by 5-25-fold) than those expressing Del19. Patients with lung cancers harboring G719X exhibited higher response rate to afatinib or neratinib (∼ 80%) than to 1G TKIs (35%-56%) by compilation of data in the literature.

CONCLUSIONS:

Lung cancers harboring exon 18 mutations should not be overlooked in clinical practice. These cases can be best treated with afatinib or neratinib, although the currently available in vitro diagnostic kits cannot detect all exon 18 mutations

Cat.No.	Product Name	Information
S7297	Osimertinib (AZD9291)	Osimertinib (AZD9291) is an oral, irreversible, and mutant-selective EGFR inhibitor with IC50 of 12.92, 11.44 and 493.8 nM for Exon 19 deletion EGFR, L858R/T790M EGFR, and WT EGFR in LoVo cells, respectively. Phase 3.
S2727	Dacomitinib	Dacomitinib is a potent, irreversible pan-ErbB inhibitor, mostly to EGFR with IC50 of 6 nM in a cell-free assay. Dacomitinib inhibits ERBB2 and ERBB4 with IC50 of 45.7 nM and 73.7 nM, respectively. Dacomitinib is effective against NSCLCs with EGFR or ERBB2 mutations as well as those harboring the EGFR T790M mutation. Dacomitinib inhibits cell growth and induces apoptosis. Phase 2.
S2150	Neratinib	Neratinib is a highly selective HER2 and EGFR inhibitor with IC50 of 59 nM and 92 nM in cell-free assays; weakly inhibits KDR and Src, no significant inhibition to Akt, CDK1/2/4, IKK-2, MK-2, PDK1, c-Raf and c-Met. Phase 3.
S7284	Rociletinib (CO-1686)	Rociletinib (CO-1686, AVL-301) is an irreversible, mutant-selective EGFR inhibitor with K_i of 21.5 nM and 303.3 nM for EGFR^L858R/T790M and EGFR^WT in cell-free assays, respectively. Phase 2.