EGFR and lung carcinoma: Novel resistance mechanisms to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR-mutant lung cancer continue to be defined.1 With the recent approval of the third-generation EGFR TKI osimertinib as first-line treatment, and expanded use of large-panel next-generation sequencing (NGS)–based testing, many novel resistance mechanisms are emerging.