ERBB2 and small cell lung carcinoma: Other mechanisms of acquired resistance to osimertinib include wild-type EGFR amplification [33], loss of T790M and other activated mutation [33], fibroblast growth factor receptor (FGFR) amplification [33], mesenchymal-epithelial transition factor (MET) amplification [56], human epidermal growth factor receptor 2 (HER2) [56], and SCLC transformation [33].