The Epidermal Growth Factor Receptor D761Y Mutation and Effect of Tyrosine Kinase Inhibitor

To the Editor: We read with great interest the November 1, 2006 article by Balak et al. ([1][1]) reporting that the epidermal growth factor receptor ( EGFR ) D761Y mutation was a “novel secondary mutation” that appeared in a metastatic brain lesion after the acquisition of gefitinib resistance.