Supersensitive Mutation: Two Case Reports of Non–Small-Cell Lung Cancer Treated With Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are indicated in second-line treatment for non–small-cell lung cancer and are, in general, well tolerated. In some patients, side effects can be problematic, necessitating dose attenuation and changes in frequency of administration. A lung tumor with an EGFR mutation confers a high treatment response rate to EGFR TKIs. We present the case reports of 2 patients, both with EGFR mutations in which excellent responses were seen despite dosages and administration frequencies far below recommended levels. In addition, in the face of apparent resistance, small increases in doses overcame this. The possible factors involved in response and resistance to EGFR TKIs and issues around length of treatment are discussed.