MET and small cell lung carcinoma: Additionally, resistance can arise from MET amplification (20%), HER2 amplification (13%), activation of bypass pathways through mutation or amplification of tyrosine kinase receptor genes like c-MET, FGFR, and HER2, mutations in downstream signaling genes like KRAS, BRAF, PIK3CA, and RAS/RAF/MEK/ERK, and transformation into small cell lung cancer (10%) (6).