However, the extent of SCLC transformation as a mechanism of resistance to EGFR inhibitors was not fully appreciated until a landmark study from Sequist et al., who profiled 37 NSCLC patients with treatment-resistant, EGFR-mutant NSCLC and identified five instances (14%) of SCLC transformation, highlighting this as a common mechanism of resistance [6]. The gene discussed is EGFR; the disease is small cell lung carcinoma.