Afatinib is especially effective against non-small cell lung cancer carrying an EGFR exon 19 deletion

Background: A recent pooled analysis of the LUX-LUNG3 and LUX-LUNG6 trials suggested that afatinib (an irreversible epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)) is especially effective against non-small cell lung cancer (NSCLC) carrying an EGFR exon 19 deletion. Materials and Methods: Stable viral transfectant HEK293 cell lines carrying an exon 19 deletion (HEK293/19 del) or exon 21 L858R mutation (HEK293/ L858R)) were created and their drug sensitivities to AG1478 (a reversible EGFR-TKI) and afatinib were examined using an MTT assay. Western blot analyses were performed to estimate the phosphorylation of EGFR. Results: In the HEK293/19 del, the 50% inhibitory concentration (IC₅₀) of afatinib was significantly lower than that in the HEK293/ L858R. In addition, afatinib inhibited the phosphorylation of EGFR to a greater degree in the HEK293/19 del than in the HEK293/L858R. Conclusion: Our experimental findings suggest that afatinib is especially effective against NSCLC carrying an EGFR exon 19 deletion.