Other mechanisms explaining EGFR‐TKI resistance include the primary resistance driven by K‐RAS mutation, activation of PI3K/AKT pathway, NF‐κB activation, EML4‐ALK gene rearrangements, EMT involvement as well as acquired resistance caused by MET amplification, loss or decreased DNA copy number of the activating EGFR mutant gene and genotypic and histological transformation from NSCLC into small cell lung cancer (Bivona et al., 2011; Coldren et al., 2006; Engelman et al., 2006; Sequist et al., 2011; Shaw et al., 2009; Tabara et al., 2012; Turke et al., 2010; Zhu et al., 2008). The gene discussed is KRAS; the disease is small cell lung carcinoma.