Adult patients with stage IIIB-IV NSCLC harboring EGFR mutations (exon 18/19/20/21) who had progressed on prior EGFR-TKIs were enrolled....Ten of 67 evaluable patients achieved confirmed partial response, with an objective response rate (ORR) of 14.9% (95% confidence interval [CI], 8.3-24.0); the ORR was 33.3%, 14.0%, 0, and 25.0% at 4 mg, 8 mg, 12 mg, and 16 mg, respectively. Besides, the ORR in patients without and with EGFR T790M mutation was 20.5% and 7.4%, respectively. Moreover, 39 patients achieved stable disease across all doses, and the disease control rate was 73.1% (95% CI, 60.9-83.2). Median progression-free survival was 4.1 (95% CI, 2.9-5.3) months....FCN-411 was well tolerated and demonstrated preliminary antitumor activity in patients with EGFR-mutated NSCLC after progression on EGFR-TKIs, especially in those without EGFR T790M mutation.