A Case Report: A Step ahead in EGFR Resistance Mechanism, Non-Small Cell Lung Cancer (NSCLC).

15% of NSCLC patients in Western countries have a mutation in Epidermal Growth Factor Receptor (EGFR). These mutations confer patients susceptibility to EGFR-Tyrosine Kinase Inhibitors (TKIs). Nevertheless, acquired resistances and secondary progressions will appear. We present a case report of a woman who had never smoked and was diagnosed of a non operable lung cancer adenocarcinoma EGFR L858R mutated treated by first line osimertinib. After progression MET amplification was found and the patient received Savolitinib added to osimertinib that had failed in the context of a C797S resistance mutation found in liquid and tissue biopsy. In this context, the patient start treatment with gefitinib with improvement of symptoms and without toxicity. This case highlights the importance of molecular testing at diagnose and after progression to TKIs, in order to improve survival in a group of patients with initial poor prognosis without target therapies.