Histological transformation from LUAD to SCLC (Memorial Sloan-Kettering Cancer Center Lung Cancer OncoGenome Group et al., 2006) occurs in 5–15% of cases with acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) (Sequist et al., 2011; Westover et al., 2018), typically after a long duration (median ≥13 months) of TKI treatment (Ferrer et al., 2019; Offin et al., 2019). The gene discussed is EGFR; the disease is small cell lung carcinoma.