Our case and the 2 additional cases reported in the literature provide evidence that EGFR delE709_T710insD may lead to enhanced sensitivity to reversible EGFR TKIs….The clinical observation that patients with tumors with this mutation achieved radiographic tumor regression may be indicative that other patients with EGFR delE709_T710insD-bearing tumors can benefit from gefitinib and/or erlotinib at their usual clinical doses.