Consistent with this result, all three lung adenocarcinoma patients with known exon 20 insertion mutants of EGFR have failed to show a clinical response to treatment and have instead achieved only stable disease with erlotinib alone (n = 1; L. Sequist and T. Lynch, personal communication), or in combination with chemotherapy (n = 2; D. Eberhard and K. Hillan, personal communication). Here, EGFR is linked to lung adenocarcinoma.