Gilteritinib是全球唯一被批准作为单一治疗药物用于携带FMS-like酪氨酸激酶3内部串联重复（FLT3-ITD）突变的急性髓细胞白血病（AML）患者。然而，在临床中不可避免地会产生耐药性。Sitravatinib是一种正在多种实体瘤临床试验中评估的多激酶抑制剂。在本研究中，我们探索了sitravatinib对FLT3-ITD及FLT3突变体AML临床相关药物抗药性的抗肿瘤活性。我们在AML细胞系和表达不同FLT3突变体的BaF3细胞中执行生长抑制实验，以评估体外sitravatinib的抗肿瘤活性。我们采用免疫印迹检验检查FLT3及其下游途径的活性。我们进行了分子对接以预测FLT3与sitravatinib的结合位点。我们在MOLM13异种移植小鼠模型和表达不同FLT3突变体的转化BaF3细胞的小鼠模型中评估了sitravatinib在体内的生存益处。我们还使用原发患者样本和患者源性异种移植（PDX）模型来确定sitravatinib的疗效。Sitravatinib抑制了FLT3-ITD AML细胞系的细胞增殖，诱导了细胞周期阻滞和凋亡。体内研究表明，与Gilteritinib相比，Sitravatinib在MOLM13异种移植模型和BaF3-FLT3-ITD模型中表现出更好的治疗效果。与Gilteritinib不同的是，Sitravatinib预测的与FLT3的结合位点不包括F691残基。Sitravatinib在体内和体外均对所有可用的FLT3抑制剂都不产生耐药性的FLT3-ITD-F691L突变产生了强大的抑制作用。与Gilteritinib相比，Sitravatinib通过更强大和稳定地抑制p-ERK和p-AKT保留了对存在细胞因子的FLT3突变的有效活性。此外，与Gilteritinib相比，FLT3-ITD患者样本对Sitravatinib的敏感性更高。我们的研究揭示了Sitravatinib在FLT3突变AML中的潜在治疗作用，并为治疗对当前FLT3抑制剂耐药的AML患者提供了一种替代抑制剂。 ©2023. 作者（们）。

Gilteritinib is the only drug approved as monotherapy for acute myeloid leukemia (AML) patients harboring FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation throughout the world. However, drug resistance inevitably develops in clinical. Sitravatinib is a multi-kinase inhibitor under evaluation in clinical trials of various solid tumors. In this study, we explored the antitumor activity of sitravatinib against FLT3-ITD and clinically-relevant drug resistance in FLT3 mutant AML.Growth inhibitory assays were performed in AML cell lines and BaF3 cells expressing various FLT3 mutants to evaluate the antitumor activity of sitravatinib in vitro. Immunoblotting was used to examine the activity of FLT3 and its downstream pathways. Molecular docking was performed to predict the binding sites of FLT3 to sitravatinib. The survival benefit of sitravatinib in vivo was assessed in MOLM13 xenograft mouse models and mouse models of transformed BaF3 cells harboring different FLT3 mutants. Primary patient samples and a patient-derived xenograft (PDX) model were also used to determine the efficacy of sitravatinib.Sitravatinib inhibited cell proliferation, induced cell cycle arrest and apoptosis in FLT3-ITD AML cell lines. In vivo studies showed that sitravatinib exhibited a better therapeutic effect than gilteritinib in MOLM13 xenograft model and BaF3-FLT3-ITD model. Unlike gilteritinib, the predicted binding sites of sitravatinib to FLT3 did not include F691 residue. Sitravatinib displayed a potent inhibitory effect on FLT3-ITD-F691L mutation which conferred resistance to gilteritinib and all other FLT3 inhibitors available, both in vitro and in vivo. Compared with gilteritinib, sitravatinib retained effective activity against FLT3 mutation in the presence of cytokines through the more potent and steady inhibition of p-ERK and p-AKT. Furthermore, patient blasts harboring FLT3-ITD were more sensitive to sitravatinib than to gilteritinib in vitro and in the PDX model.Our study reveals the potential therapeutic role of sitravatinib in FLT3 mutant AML and provides an alternative inhibitor for the treatment of AML patients who are resistant to current FLT3 inhibitors.© 2023. The Author(s).