Enhancing FLT3 inhibitor efficacy in acute myeloid leukemia with FLT3-ITD

利用 FLT3-ITD 增强 FLT3 抑制剂对急性髓系白血病的疗效

• 批准号: 10664857
• 负责人: MARIA R BAER
• 金额: --
• 依托单位: BALTIMORE VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10664857
• 关键词: Acute Myelocytic Leukemia; Acute leukemia; Adult; Aftercare; Age; Allogenic; Apoptotic; Award; Cell Line; Cells; Clinical Trials; Development; Down-Regulation; Exhibits; FLT3 gene; FRAP1 gene; Feedback; Genetic Transcription; Goals; Health; Hematopoietic Stem Cell Transplantation; In Vitro; Incidence; Induction of Apoptosis; MCL1 gene; MEKs; Malignant Neoplasms; Mediating; Medical; Military Personnel; Molecular; Molecular Abnormality; Mutate; Mutation; Newly Diagnosed; Oncogenic; Oral; PI3K/AKT; PIM-1 Serine/Threonine Kinase; Pathway interactions; Patient-Focused Outcomes; Patients; Pharmaceutical Preparations; Phosphorylation; Phosphotransferases; Point Mutation; Protein Serine/Threonine Phosphatase; Protein phosphatase; Proteins; Proto-Oncogene Proteins c-akt; Receptor Protein-Tyrosine Kinases; Refractory; Relapse; Resistance; Resistance development; Sampling; Signal Induction; Signal Pathway; Signal Transduction; Stat5 protein; Survival Rate; Testing; Transcriptional Activation; Transducers; Treatment outcome; Tumor Suppressor Proteins; Veterans; White Blood Cell Count procedure; Work; acute myeloid leukemia cell; c-myc Genes; chemotherapy; disorder control; efficacy evaluation; efficacy testing; improved; improved outcome; in vivo; inhibitor; inhibitor therapy; kinase inhibitor; knock-down; men; military service; prevent; proto-oncogene protein pim; response; targeted agent; transcription factor; treatment response; ubiquitin isopeptidase

Acute myeloid leukemia (AML), the common type of acute leukemia in adults, is an important health concern for Veterans due to its high incidence and frequent poor response to treatment. Internal tandem duplication (ITD) of the fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is present in AML cells of 30% of patients and is associated with poor treatment outcomes. FLT3 inhibitors have activity, but responses are limited and transient, with rapid development of resistance occurring by diverse mechanisms. FLT3-ITD causes constitutive FLT3 signaling, which is also aberrant. In addition to activating the PI3K/AKT/mTOR and MEK/ERK/RAS pathways, which are activated by signaling of wild-type FLT3, FLT3-ITD activates signal transducer and activation of transcription (STAT) 5, which transcriptionally upregulates the oncogenic serine threonine kinase Pim-1. Pim-1 contributes directly to the proliferative and anti-apoptotic effects of FLT3-ITD, and also phosphorylates and stabilizes FLT3, promoting STAT5 signaling in a positive feedback loop in cells with FLT3-ITD. Cells with FLT3-ITD also exhibit inactivation of the serine/threonine phosphatase protein phosphatase 2A (PP2A), which has tumor suppressor activity. The transcription factor c- Myc is transcriptionally upregulated downstream of FLT3-ITD, along with Pim-1, and knockdown of c-Myc or Pim-1 has anti-proliferative effects in cells with FLT3-ITD. In addition, PP2A and Pim-1 both regulate c-Myc post-translationally. We hypothesize that concurrent targeting of aberrant signaling pathways will enhance the efficacy of FLT3 inhibitors and prevent development of resistance to FLT3 inhibitors, and overcome resistance. Mechanisms of acquired resistance to FLT3 inhibitors include development of point mutations in the FLT3 kinase domain, a FLT3-dependent mechanism, and of RAS mutations - a FLT3-independent mechanism. Expression of Pim kinases is also further upregulated in cells with FLT3-ITD with FLT3 inhibitor resistance. Work in our prior VA Merit Award focused on cellular and molecular effects of pan-Pim kinase inhibition in AML cells with FLT3-ITD. Pim inhibition has little effect by itself, but potentiates the anti-proliferative and pro- apoptotic effects of FLT3 inhibitors and of chemotherapy drugs in cells with FLT3-ITD. We found that Pim inhibition enhances induction of apoptosis of AML cells with FLT3-ITD by FLT3 inhibitors in vitro and in vivo via post-translational downregulation of the anti-apoptotic protein Mcl-1 and its deubiquitinase USP9X. We subsequently found that post-translational c-Myc downregulation precedes these changes. We also found that concurrent treatment of cells with FLT3-ITD with PP2A-activating drugs and FLT3 inhibitors causes post-translational downregulation of c-Myc and Pim-1; and that these effects are mediated by AKT inactivation-dependent activation of GSK-3 which phosphorylates both c-Myc and Pim-1, enhancing their proteasomal degradation. The overall hypothesis of this Merit award proposal is that concurrent treatment with PP2A activating drugs or Pim kinase inhibitors enhances the efficacy of FLT3 inhibitors in AML with FLT3-ITD, abrogates or delays development of FLT3 inhibitor resistance, and has the potential to re-sensitize cells with FLT3 inhibitor resistance occurring by diverse mechanisms. Our Specific Aims are: 1. To test the hypothesis that PP2A-activating drugs and Pim kinase inhibitors increase FLT3 inhibitor efficacy through GSK-3-mediated post-translational c-Myc downregulation; 2. To test the efficacy of PP2A-activating drug or Pim inhibitor co-treatment in preventing FLT3 inhibitor resistance; and 3. To determine the efficacy of Pim inhibitor or PP2A-activating drug co-treatment in re-sensitizing AML cells with FLT3-ITD with FLT3 inhibitor resistance occurring by diverse mechanisms. The long-term objective is to develop clinical trials, with the ultimate goal of improving outcomes for patients with AML with FLT3-ITD, a common AML subtype with poor treatment outcome.

急性髓样白血病（AML）是成人急性白血病的常见类型，是重要的健康 担心退伍军人由于其高事件而经常对治疗的反应不佳。内部串联 FMS样酪氨酸激酶3（FLT3）受体酪氨酸激酶的重复（ITD）存在于AML细胞中 30％的患者与治疗结果不佳有关。 FLT3抑制剂具有活性，但反应 有限且短暂的，抗药性的快速发展是由潜水机制发生的。 FLT3-ITD会导致组成型FLT3信号传导，这也是异常的。除了激活 PI3K/AKT/MTOR和MEK/ERK/RAS途径，通过野生型FLT3，FLT3-ITD的信号激活 激活信号换能器和转录的激活（Stat）5，转录会更新 致癌丝氨酸苏氨酸激酶PIM-1。 PIM-1直接有助于增殖和抗凋亡 FLT3-ITD的效果，还磷酸化并稳定FLT3，促进阳性的STAT5信号传导 带有FLT3-ITD的细胞中的反馈回路。具有FLT3-ITD的细胞也表现出串行/苏氨酸的失活 磷酸酶蛋白磷酸酶2a（PP2A），具有肿瘤抑制活性。转录因子c- MYC是FLT3-ITD下游的转录更新，以及PIM-1，以及C-Myc或 PIM-1在具有FLT3-ITD的细胞中具有抗增殖作用。此外，PP2A和PIM-1都调节C-MYC 后翻译。我们假设同时靶向异常信号通路将增强 FLT3抑制剂的功效并防止对FLT3抑制剂的抗性发展并克服抗性。 对FLT3抑制剂的抗性机制包括在FLT3中的点突变的发展 激酶结构域，一种依赖FLT3的机制和RAS突变 - 一种独立于FLT3的机制。 在具有FLT3抑制剂耐药性的FLT3-ITD细胞中，PIM激酶的表达也进一步更新。 在我们先前的VA优点奖中的工作，重点介绍了Pan-Pim激酶抑制的细胞和分子效应 带有FLT3-ITD的AML细胞。 PIM抑制本身几乎没有影响，但抗增殖剂和利益潜力 FLT3-ITD细胞中FLT3抑制剂和化学疗法药物的凋亡作用。我们发现PIM 通过FLT3抑制剂在体外和体内对AML细胞凋亡的抑制增强诱导AML细胞的凋亡 通过抗凋亡蛋白MCL-1及其去偶四酶USP9X的翻译后下调。我们 随后发现，翻译后C-MYC下调在这些变化之前。我们还发现 通过PP2A激活药物和FLT3抑制剂的引起的FLT3-ITD并同时处理细胞 C-MYC和PIM-1的翻译后下调；这些效果是由AKT介导的 GSK-3的灭活依赖性激活，磷酸化C-MYC和PIM-1，增强其增强 蛋白酶体降解。 该优点奖励提案的总体假设是与PP2A激活的同时治疗 药物或PIM激酶抑制剂可提高使用FLT3-ITD，废除或 延迟FLT3抑制剂的耐药性的发展，并具有将FLT3重新敏感细胞的潜力 抑制剂耐药性通过各种机制产生。 我们的具体目的是：1。检验PP2A激活药物和PIM激酶抑制剂的假设 通过GSK-3介导的翻译后C-MYC下调提高FLT3抑制剂效率； 2。测试 PP2A激活药物或PIM抑制剂在防止FLT3抑制剂耐药性方面的效率；和 3。确定PIM抑制剂或PP2A激活药物共同处理在重新敏感的AML细胞中的效率 具有FLT3-ITD具有FLT3抑制剂的耐药性，这是由不同的机制产生的。 长期目标是开发临床试验，其最终目的是改善结果 AML患有FLT3-ITD的患者是一种常见的AML亚型，治疗结果差。