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: 10260844
• 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/10260844
• 关键词: Acute Myelocytic Leukemia; Acute leukemia; Adult; Aftercare; Age; Allogenic; Apoptotic; Award; Cell Line; Cells; Clinical Trials; Development; Disease; Down-Regulation; Exhibits; FRAP1 gene; Feedback; Genetic Transcription; Glycogen Synthase Kinase 3; 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; Phosphotransferases; Point Mutation; Protein Serine/Threonine Phosphatase; Protein Tyrosine Kinase; Protein phosphatase; Proteins; Proto-Oncogene Proteins c-akt; Refractory; Relapse; Resistance; Resistance development; Sampling; 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; efficacy testing; fetal liver kinase-2; improved; improved outcome; in vivo; inhibitor/antagonist; kinase inhibitor; knock-down; men; military service; prevent; proto-oncogene protein pim; receptor; response; targeted agent; transcription factor; treatment response

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.

急性髓细胞白血病（AML）是成人急性白血病的常见类型，是一种重要的健康问题。 由于其高发病率和经常对治疗反应不佳，因此值得关注。内部串联 fms样酪氨酸激酶3（FLT 3）受体酪氨酸激酶的复制（ITD）存在于AML细胞中， 30%的患者，并与治疗效果差相关。FLT 3抑制剂具有活性，但反应 是有限的和短暂的，与快速发展的阻力发生不同的机制。 FLT 3-ITD导致组成型FLT 3信号传导，这也是异常的。除了激活 PI 3 K/AKT/mTOR和MEK/ERK/RAS通路，通过野生型FLT 3、FLT 3-ITD的信号传导激活 激活信号转导和转录激活（STAT）5，转录上调 致癌丝氨酸苏氨酸激酶Pim-1。Pim-1直接促进细胞的增殖和抗凋亡。 FLT 3-ITD的作用，也磷酸化和稳定FLT 3，促进STAT 5信号传导， FLT 3-ITD细胞中的反馈回路。具有FLT 3-ITD的细胞也表现出丝氨酸/苏氨酸的失活， 磷酸酶蛋白磷酸酶2A（PP 2A），其具有肿瘤抑制活性。转录因子c- Myc在FLT 3-ITD下游转录上调，沿着Pim-1，c-Myc或 Pim-1对FLT 3-ITD细胞具有抗增殖作用。此外，PP 2A和Pim-1都调节c-Myc 事后的我们假设，同时靶向异常信号通路将增强 FLT 3抑制剂的功效和防止对FLT 3抑制剂的耐药性的发展，并克服耐药性。 对FLT 3抑制剂的获得性耐药性的机制包括FLT 3中的点突变的发展。 激酶结构域，FLT 3依赖性机制和RAS突变-FLT 3非依赖性机制。 Pim激酶的表达在具有FLT 3抑制剂抗性的FLT 3-ITD细胞中也进一步上调。 我们之前的VA优异奖的工作集中在泛Pim激酶抑制的细胞和分子效应， FLT 3-ITD的AML细胞。Pim抑制本身几乎没有影响，但增强了抗增殖和促增殖作用。 FLT 3抑制剂和化疗药物在FLT 3-ITD细胞中的凋亡作用。我们发现皮姆 抑制增强FLT 3抑制剂在体外和体内诱导FLT 3-ITD AML细胞凋亡 通过抗凋亡蛋白Mcl-1及其去泛素化酶USP 9 X的翻译后下调。我们 随后发现，翻译后c-Myc下调先于这些变化。我们还发现 用PP 2A激活药物和FLT 3抑制剂同时处理FLT 3-ITD细胞， c-Myc和Pim-1的翻译后下调;这些作用由AKT介导 GSK-3激酶的失活依赖性活化，其磷酸化c-Myc和Pim-1，增强它们的 蛋白酶体降解 本Merit奖提案的总体假设是，与PP 2A激活剂同时治疗 药物或Pim激酶抑制剂增强FLT 3抑制剂在伴有FLT 3-ITD的AML中的疗效， 延迟FLT 3抑制剂耐药性的发展，并有可能使细胞对FLT 3重新敏感 抑制剂耐药性的发生机制多种多样。 我们的具体目标是：1。为了验证PP 2A激活药物和Pim激酶抑制剂 通过GSK-3 β介导翻译后c-Myc下调增加FLT 3抑制剂功效; 2.测试 PP 2A活化药物或Pim抑制剂共同治疗在预防FLT 3抑制剂抗性中的功效;以及 3.确定Pim抑制剂或PP 2A活化药物共同治疗在再致敏AML细胞中的功效 FLT 3-ITD，FLT 3抑制剂耐药性通过不同机制发生。 长期目标是开展临床试验，最终目标是改善 FLT 3-ITD的AML患者，FLT 3-ITD是一种治疗结果较差的常见AML亚型。