Among the 21 efficacy evaluable patients, ORR was 85.71% (95% CI, 63.66-96.95) with a duration of response (DOR) of 22.2 months (95% CI, 8.4-NA). Disease control rate (DCR) was 100% (95% CI, 83.89-100.00). Median progression-free survival (mPFS) was 20.6 months (95% CI, 8.3-NA)....Mefatinib has shown promising anti-tumor activity and a favorable safety profile in patients with advanced NSCLC harboring rare EGFR mutations.