First-in-human phase I study of BEBT-109 in previously treated EGFR exon 20 insertion-mutated advanced non-small cell lung cancer

BACKGROUND

BEBT-109 is an oral pan-mutant-selective inhibitor of epidermal growth factor receptor (EGFR) that demonstrated promising antitumor potency in preclinical models.

METHODS

This first-in-human study was a single-arm, open-label, two-stage study. Phase Ia dose-escalation study evaluated the safety and pharmacokinetics of BEBT-109 in 11 patients with EGFR T790M-mutated advanced non-small cell lung cancer (aNSCLC). Phase Ib dose-expansion study evaluated the safety and efficacy of BEBT-109 in 18 patients with EGFR exon 20 insertion (ex20ins)-mutated treatment-refractory aNSCLC. The primary outcomes were adverse events and antitumor activity. Clinical trial registration number CTR20192575.

FINDINGS

The phase Ia study demonstrated no dose-limiting toxicity, no observation of the maximum tolerated dose, and no new safety signals with BEBT-109 in the dose range of 20-180 mg/d, suggesting that BEBT-109 had an acceptable safety profile among patients with EGFR T790M-mutated aNSCLC. Plasma pharmacokinetics of BEBT-109 showed a dose-proportional increase in the area under the curve and maximal concentration, with no significant drug accumulation. The dose-expansion study demonstrated that BEBT-109 treatment was tolerable across the three dose levels. The three most common treatment-related adverse events were diarrhea (100%; 22.2% ≥Grade 3), rash (66.7%; 5.6% ≥Grade 3), and anemia (61.1%; 0% ≥Grade 3). The objective response rate was 44.4% (8 of 18). Median progression-free survival was 8.0 months (95% confidence intervals, 1.33-14.67).

CONCLUSION

Preliminary findings showed that BEBT-109 had an acceptable safety profile and favorable antitumor activity in patients with refractory EGFR ex20ins-mutated aNSCLC.

FUNDING

National Natural Science Foundation of China.

BEBT-109, a pan-mutant-selective EGFR inhibitor with potent antitumor activity in EGFR-mutant non-small cell lung cancer

•

BEBT-109 is a potent pan-mutant-selective EGFR inhibitor.

•

Pharmacokinetic profiles of BEBT-109 minimize the off-target toxicity.

•

Two major metabolites of BEBT-109 show no wild-type EGFR inhibition.

•

BEBT-109 demonstrates potent antitumor activity in the clinical trial.

EGFR mutation-positive NSCLC tumors are highly heterogeneous, therefore, exploring an agent simultaneously targeting multiple EGFR mutations may be valuable for clinical practice. Compared with osimertinib, BEBT-109 shows more sensitive and extensive antitumor activity in EGFR mutant NSCLC, while sparing wild-type EGFR cell lines. Meanwhile, unlike the metabolite of osimertinib AZ5104, the main metabolites of BEBT-109 are found lacking in activity against wild-type EGFR cell lines. Preclinical and clinical studies demonstrate a unique pharmacokinetic profiles of BEBT-109 with rapid absorption and quick in vivo clearance without accumulation, which are conducive to minimizing the off-target toxicity of the covalent irreversible EGFR inhibitor. Oral administration of BEBT-109 induces tumor regression in EGFR exon 20 insertion xenografts, and even tumor disappearance in PC-9, HCC827 and H1975 xenograft models. Furthermore, in clinical trials, the objective responses were observed in NSCLC patients with EGFR T790M mutation in the first and second dosing cohorts. These findings demonstrate that BEBT-109, a potent pan-mutant-selective EGFR inhibitor with improved pharmacokinetic properties, might offer a promising new option for the treatment of multiple mutant-EGFR-driven NSCLC.