Abstract 597: Vebreltinib: A novel brain-penetrating MET kinase inhibitor demonstrates the mechanism of action and pharmacological anti-tumor activity in diverse patient-derived MET-dysregulated tumor models at clinically relevant drug levels

Abstract Background: Dysregulation of the MET signaling pathway drives oncogenesis in many human cancers, the majority of which have not been addressed by a MET targeted therapy albeit the emerging therapies for MET exon 14 skipping (MET ex14) NSCLC. We have developed a novel highly selective MET kinase inhibitor vebreltinib (APL-101, PLB1001, bozitinib) to address unmet medical need. Vebreltinib is being jointly investigated in ongoing pivotal Phase 2 and 2/3 studies in MET-dysregulated NSCLC, primary CNS cancers and basket solid tumors in China (as PLB-1001) and globally ex-China (as APL-101). The Phase 1 portion of both studies have been concluded with the same RP2D (200 mg BID by oral administration). Vebreltinib demonstrated blood-brain barrier permeability in PLB-1001 Phase 1 glioblastoma study as previously reported. Methods: MET enzyme kinetics and vebreltinib intrinsic potency were studied by a radiometric MET kinase assay. Selectivity was profiled by in vitro KINOME. Vebreltinib cellular activity on MET signaling and in vivo anti-tumor activity were assessed in tumor cell lines and patient-derived tumors (PDX) carrying MET alterations. Results: Vebreltinib is an ATP-competitive inhibitor with Ki of approximately 2. 2 nM for recombinant MET kinase and inhibited the native form of activated MET with 0. 52 nM IC50. Vebreltinib demonstrated exquisite selectivity in KINOMEscan selectivity panel. Vebreltinib inhibited HGF-dependent and -independent MET signaling in KP4 tumor cell lines with nanomolar concentrations. Vebreltinib inhibited IL-3 independent Ba/F3 cell lines carrying exogenous MET ex14 or with secondary mutations induced by other MET TKIs. Vebreltinib inhibited MKN45 gastric tumor xenograft in vivo with ED90 of 6 mg/kg PO/QD. Furthermore, Vebreltinib demonstrated strong anti-tumor activity in a variety of PDX tumor types carrying MET ex14, MET fusions, and MET amplification. In these preclinical studies, the total and unbound vebreltinib plasma concentration observed at steady state trough of RP2D was used as a clinically relevant drug level to interpret Vebreltinib efficacy in blocking oncogenic MET signaling, proliferation of Ba/F3 cell lines with a broad spectrum of MET mutations and in vivo tumor growth in PDXs carrying diverse MET alterations. We demonstrated the rationale for Vebreltinib to be an efficacious single-agent MET inhibitor in treating tumors carrying MET driver alterations beyond MET ex14 NSCLC. Conclusion: Vebreltinib is a novel potent MET kinase inhibitor showing promising preclinical activity against PDXs from diverse organs sites and genomic alterations such as MET ex14, MET fusion, MET amplification, or HGF over-expression at clinically relevant drug levels, providing proof-of-concepts for continued clinical development. Citation Format: Xiaoling Zhang, Elaine Liu, Yan Song, Peony Yu, Sanjeev Redkar, Guo-Liang Yu. Vebreltinib: A novel brain-penetrating MET kinase inhibitor demonstrates the mechanism of action and pharmacological anti-tumor activity in diverse patient-derived MET-dysregulated tumor models at clinically relevant drug levels abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 597.