Although clinical results have demonstrated that erlotinib monotherapy showed a survival benefit in comparison with gemcitabine for patients with NSCLC or pancreatic cancer, resistance to erlotinib reduces its efficacy.20, 21 The T790M point mutation in EGFR causes a conformational change at the ATP binding pocket, thus decreasing the affinity between erlotinib and EGFR and leading to acquired/secondary resistance.22, 23. This evidence concerns the gene EGFR and non-small cell lung carcinoma.