Discovery of 1‑(4-(4-Amino-3-(4-(2-morpholinoethoxy)­phenyl)‑1<i>H</i>‑pyrazolo[3,4‑<i>d</i>]­pyrimidin-1-yl)­phenyl)-3-(5‑(<i>tert</i>-butyl)­isoxazol-3-yl)­urea (CHMFL-FLT3-213) as a Highly Potent Type II FLT3 Kinase Inhibitor Capable of Overcoming a Variety of FLT3 Kinase Mutants in FLT3-ITD Positive AML

FLT3-ITD mutant has been observed in about 30% of AML patients and extensively studied as a drug discovery target. On the basis of our previous study that ibrutinib (9) exhibited selective and moderate inhibitory activity against FLT3-ITD positive AML cells, through a structure-guided drug design approach, we have discovered a new type II FLT3 kinase inhibitor, compound 14 (CHMFL-FLT3-213), which exhibited highly potent inhibitory effects against FLT3-ITD mutant and associated oncogenic mutations (including FLT3-D835Y/H/V, FLT3-ITD-D835Y/I/N/A/G/Del, and FLT3-ITD-F691L). In the cellular context 14 strongly affected FLT3-ITD mediated signaling pathways and induced apoptosis by arresting cell cycle into G0/G1 phase. In the in vivo studies 14 demonstrated an acceptable bioavailability (F = 19%) and significantly suppressed the tumor growth in MV4-11 cell inoculated xenograft model (15 mg kg–1 day–1, TGI = 97%) without exhibiting obvious toxicity. Compound 14 might be a potential drug candidate for FLT3-ITD positive AML.FMS样酪氨酸激酶3内部串联重复（FLT3-ITD）突变在约30%的急性髓系白血病（Acute Myeloid Leukemia, AML）患者中被发现，且作为药物研发靶点得到了广泛研究。基于本团队此前关于依鲁替尼（ibrutinib，编号9）对FLT3-ITD阳性AML细胞具有选择性中等强度抑制活性的研究，我们通过结构导向药物设计策略，发现了一类新型II型FLT3激酶抑制剂——化合物14（CHMFL-FLT3-213）。该化合物对FLT3-ITD突变及相关致癌突变（包括FLT3-D835Y/H/V、FLT3-ITD-D835Y/I/N/A/G/Del以及FLT3-ITD-F691L）均表现出强效抑制活性。在细胞层面，化合物14可显著干扰FLT3-ITD介导的信号通路，并通过将细胞周期阻滞于G0/G1期诱导细胞凋亡。体内研究结果显示，化合物14具有可接受的生物利用度（Bioavailability, F=19%），并在MV4-11细胞接种的异种移植瘤模型中以15 mg·kg⁻¹·d⁻¹的给药剂量显著抑制肿瘤生长（肿瘤生长抑制率Tumor Growth Inhibition, TGI=97%），且未表现出明显毒性。化合物14有望成为FLT3-ITD阳性AML的潜在候选药物。