Abstract A094: Preclinical characterization of HMPL-415, a second-generation SHP2 inhibitor

Abstract

Abstract Background: Oncogenic activation of the RAS/MAPK signaling pathway is one of the leading causes for driving a variety of cancers. Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) functions downstream of multiple RTKs, and integrates growth factor signals to promote RAS activation, making it an attractive drug target for cancers harboring oncogenic alterations in RAS/MAPK pathway. Herein, we present the preclinical characterization of HMPL-415, a highly potent, selective and non-competitive SHP2 inhibitor, discovered and being currently developed in phase I clinical trial (NCT05886374) by HUTCHMED. Methods: The inhibition of HMPL-415 on the full length and catalytic domain of SHP2 was detected by a biochemical DIFMUP pseudosubstracte-fluorgenic assay. For selectivity, HMPL-415 was assessed against a panel of 413 kinases and 21 phosphatases by Eurofins. The modulation of HMPL-415 on RAS/MAPK signaling cascades was evaluated by western blot. In vitro anti-proliferation activity was measured by CellTiter-Glo luminescent assay. Multiple human xenograft tumors with RAS/MAPK pathway activation were applied in immune-deficient mice to investigate the anti-tumor activity of HMPL-415. Results: In vitro, HMPL-415 displayed higher potency in enzyme (5 fold) and cellular target inhibition (> 20 fold) compared to first-generation SHP inhibitor TNO155. It strongly inhibited full length of human SHP2 with an IC50 of 0.4 nM, while had no inhibitory activity up to 10 µM against the catalytic domain of SHP2. In NCI-H358 (KrasG12C), NCI-H508 (class Ⅲ BRAFG596R), and NCI-H1838 (NF1N184fs) cells, HMPL-415 inhibited p-ERK with IC50s of 1~3 nM, and significantly suppressed downstream molecules p-RSK and p-S6. Through inhibition of RAS/MAPK signaling pathway, HMPL-415 robustly inhibited cell proliferation in a panel of human cancer cell lines with KRAS G12C/V, BRAF class Ⅲ, NF1 loss of function (LOF), RTK mutations or KRAS amplification (median GI50 =1 nM) compared to cell lines harboring KRAS G12D, G13 or Q61 mutations (median GI50 >1 µM), indicating a dependence on specific KRAS nucleotide-cycling for anti-tumor effect. Furthermore, the selectivity across panels of 413 kinases and 21 phosphatases revealed that HMPL-415 should have a low off-target risk. In vivo, oral administration of HMPL-415 showed prolonged and high tumor exposure and sustained inhibition on RAS/MAPK signaling after repeat dosing. In human xenograft models carrying KRAS, BRAF class Ⅲ, NF1LOF, and EGFR alterations, HMPL-415 dose-dependently induced tumor growth inhibition at continuous daily doses that were well tolerated. Tumor regression was observed in most tumor models tested at the dose of 3 mg/kg/day, which demonstrated much superior anti-tumor activity than that of TNO155 at 30 mg/kg/day. Conclusion: HMPL-415 is a highly potent, selective and non-competitive SHP2 inhibitor that demonstrates strong anti-tumor activity in vitro and in vivo, supporting further clinical evaluation. Citation Format: Jia Hu, Jun Ni, Zhihu Gao, Xiaoqing Liu, Hui Zhang, Pan Wang, Min Cheng, Guanglin Wang, Zeyu Zhong, Jian Wang, Yang Sai, Na Yang, Weiguo Qing, Yongxin Ren, Michael Shi, Weiguo Su. Preclinical characterization of HMPL-415, a second-generation SHP2 inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A094.