Erlotinib, a kinase inhibitor targeting EGFR, initially was used successfully as a second-line treatment in NSCLC patients that progressed on standard chemotherapy.1 However, it was soon discovered that gefitinib (another EGFR-directed tyrosine kinase inhibitor (TKI)) and erlotinib were especially effective in patients with an activating mutation in EGFR. 2, 3, 4 These patients are now offered EGFR-TKIs as first-line treatment.5, 6 Many EGFR-mutated patients experience a pronounced initial effect of this treatment, but all acquire resistance over time. Here, EGFR is linked to non-small cell lung carcinoma.