A Novel Third-generation EGFR Tyrosine Kinase Inhibitor Abivertinib for EGFR T790M-mutant Non-Small Cell Lung Cancer: a Multicenter Phase I/II Study

To establish recommended phase II dose (RP2D) in phase I and evaluate safety and efficacy of abivertinib in patients with EGFR Thr790Met point mutation (T790M)-positive(+) non-small cell lung cancer (NSCLC) with disease progression from prior EGFR inhibitors in phase II. This multicenter, open-label study included 367 adult Chinese patients. Abivertinib at doses of 50 mg twice a day to 350 mg twice a day was evaluated in phase I in continual 28-day cycles, and the RP2D of 300 mg twice a day was used in phase II in continual 21-day cycles. Primary endpoints include RP2D in phase I and objective response rate (ORR) at RP2D in phase II. The RP2D of 300 mg twice a day for abivertinib was established based on pharmacokinetics, efficacy, and safety profiles across doses in phase I. In phase II, 227 patients received RP2D for a median treatment duration of 24.6 weeks (0.43-129). Among 209 response-evaluable patients, confirmed ORR was 52.2% [109/209; 95% confidence interval (CI): 45.2-59.1]. Disease control rate (DCR) was 88.0% (184/209; 95% CI: 82.9-92.1). The median duration of response (DoR) and progression-free survival (PFS) was 8.5 months (95% CI: 6.1-9.2) and 7.5 months (95% CI: 6.0-8.8), respectively. The median overall survival (OS) was 24.9 months [95% CI: 22.4-not reachable (NR)]. All (227/227) patients reported at least 1 adverse event (AE), with 96.9% (220/227) of treatment-related AEs. Treatment-related serious AEs were reported in 13.7% (31/227) of patients. Death was reported in 4.4% (10/227) of patients, and none was deemed as treatment-related. Abivertinib of 300 mg twice a day demonstrated favorable clinical efficacy with manageable side effects in patients with EGFR T790M+ NSCLC.