EGFR and neoplasm: In in vitro study, tumor cells harboring C797S mutation without T790M mutation are still sensitive to quinazoline-based EGFR inhibitors like gefitinib or erlotinib, and, harboring EGFR C797S in trans with T790M mutations are sensitive to a combination of first- and third-generation EGFR-TKI and in cis are resistant to all current EGFR inhibitors [18, 19].