Discovery of <i>N</i>‑((1-(4-(3-(3-((6,7-Dimethoxyquinolin-3-yl)oxy)phenyl)­ureido)-2-(trifluoromethyl)­phenyl)­piperidin-4-yl)methyl)­propionamide (CHMFL-KIT-8140) as a Highly Potent Type II Inhibitor Capable of Inhibiting the T670I “Gatekeeper” Mutant of cKIT Kinase

cKIT kinase inhibitors, e.g., imatinib, could induce drug-acquired mutations such as cKIT T670I that rendered drug resistance after chronic treatment. Through a type II kinase inhibitor design approach we discovered a highly potent type II cKIT kinase inhibitor compound 35 (CHMFL-KIT-8140), which potently inhibited both cKIT wt (IC50 = 33 nM) and cKIT gatekeeper T670I mutant (IC50 = 99 nM). Compound 35 displayed strong antiproliferative effect against GISTs cancer cell lines GIST-T1 (cKIT wt, GI50 = 4 nM) and GIST-5R (cKIT T670I, GI50 = 26 nM). In the cellular context it strongly inhibited c-KIT mediated signaling pathways and induced apoptosis. In the BaF3-TEL-cKIT-T670I isogenic cell inoculated xenograft mouse model, 35 exhibited dose dependent tumor growth suppression efficacy and 100 mg/kg dosage provided 47.7% tumor growth inhibition (TGI) without obvious toxicity. We believe compound 35 would be a good pharmacological tool for exploration of the cKIT-T670I mutant mediated pathology in GISTs.cKIT激酶抑制剂，例如伊马替尼（imatinib），长期给药治疗后可诱导药物获得性突变（如cKIT T670I突变），进而引发肿瘤耐药。本研究通过II型激酶抑制剂设计策略，发现了一款强效II型cKIT激酶抑制剂化合物35（CHMFL-KIT-8140），其对cKIT野生型（wild type, wt）和cKIT守门突变体T670I均展现出强效抑制活性，半最大抑制浓度（IC50）分别为33 nM和99 nM。化合物35对胃肠道间质瘤（Gastrointestinal Stromal Tumors, GIST）细胞系GIST-T1（cKIT野生型，半最大生长抑制浓度GI50=4 nM）和GIST-5R（cKIT T670I突变型，GI50=26 nM）均表现出显著的抗增殖活性。在细胞水平上，化合物35可有效抑制c-KIT介导的信号通路，并诱导细胞凋亡。在接种BaF3-TEL-cKIT-T670I同基因细胞的异种移植小鼠模型中，化合物35展现出剂量依赖性的肿瘤生长抑制效果；当给药剂量为100 mg/kg时，肿瘤生长抑制率（Tumor Growth Inhibition, TGI）可达47.7%，且未观察到明显毒性反应。我们认为，化合物35可作为一款优秀的药理学工具，用于探究胃肠道间质瘤中cKIT-T670I突变介导的病理机制。