EGFR and non-small cell lung carcinoma: Work from Hata et al. [16] modelling the development of EGFR inhibitor (EGFRi) resistance in NSCLC in vitro has shown that acquisition of the EGFR gatekeeper mutation, T790M, can occur either through the accumulation of the mutation in drug-tolerant persister cells or through the selection of pre-existing clones which already possess the mutation.