Mechanisms to TKI resistance include the development of a recurrent T790M EGFR mutation, amplification of signalling molecules that bypass EGFR inhibition (such as MET and HER2), mutations in other oncogenic drivers (eg, PIK3CA and B-RAF) and conversion to small-cell lung cancer (SCLC).64–69 In this context, the possibility to interrogate lung cancer genotype in real time through liquid biopsies is of paramount importance. This evidence concerns the gene ERBB2 and small cell lung carcinoma.