10PEGFR T790M mutation in treatment-naïve tumor samples: Low frequency, evidence for interaction with EGFR TKI-sensitizing mutations and lack of clear predictive value

Background: EGFR T790M mutation is associated with acquired resistance of lung cancer (LC) to first-generation TKIs. Several studies suggest that LCs often contain a small fraction of T790M-mutated cells even before the treatment, and the persistence of these mosaic clones renders poor tumor response to gefitinib or erlotinib.