EGFR and small cell lung carcinoma: T790 M mutation accounts for approximately 60% of the resistance cases in first-generation tyrosine kinase inhibitor (TKIs) treatment.[1,2] Third-generation TKIs such as osimertinib were effective against T790 M mutated NSCLC, with overall response rate of about 60%, but acquired resistance occur in about 10 months.[3] After either first-generation or third-generation EGFR TKIs, transformation to SCLC has been described as a mechanism of resistance to EGFR TKIs in approximately 5% of patients.[1,2,4]