EGFR and non-small cell lung carcinoma: However, NSCLC patients with EGFR ex20ins mutations have reduced response to EGFR TKIs compared to those harboring classical mutations (EGFR ex19Del and EGFR ex21L858R).[5] Currently, no EGFR TKIs are approved for first-line treatment of NSCLC patients with EGFR ex20ins mutations in China.