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.

急性髓系白血病（AML）是成人急性白血病的常见类型，是一种重要的健康问题 由于其高发病率和治疗反应经常不佳而引起退伍军人的关注。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% 的患者与不良治疗结果相关。 FLT3抑制剂有活性，但反应 耐药性是有限且短暂的，通过不同的机制发生耐药性的快速发展。 FLT3-ITD 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 通路，由野生型 FLT3、FLT3-ITD 信号激活 激活信号转导器和转录激活 (STAT) 5，从而上调转录 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 的作用，并且还磷酸化和稳定 FLT3，以正向促进 STAT5 信号传导 具有 FLT3-ITD 的细胞中的反馈回路。带有 FLT3-ITD 的细胞也表现出丝氨酸/苏氨酸失活 磷酸酶蛋白磷酸酶2A (PP2A)，具有肿瘤抑制活性。转录因子 c- Myc 与 Pim-1 一起在 FLT3-ITD 下游转录上调，并敲低 c-Myc 或 Pim-1 对带有 FLT3-ITD 的细胞具有抗增殖作用。此外，PP2A 和 Pim-1 均调节 c-Myc 翻译后。我们假设同时靶向异常信号通路将增强 FLT3抑制剂的功效，防止FLT3抑制剂耐药性的发展，并克服耐药性。 FLT3 抑制剂获得性耐药机制包括 FLT3 点突变的发生 激酶结构域（FLT3 依赖性机制）和 RAS 突变（FLT3 独立机制）。 在具有 FLT3 抑制剂抗性的 FLT3-ITD 细胞中，Pim 激酶的表达也进一步上调。 我们之前 VA 优异奖的工作重点是泛 Pim 激酶抑制的细胞和分子效应 带有 FLT3-ITD 的 AML 细胞。 Pim 抑制本身作用不大，但可增强抗增殖和促增殖作用。 FLT3抑制剂和化疗药物对FLT3-ITD细胞的凋亡作用。我们发现皮姆 体外和体内 FLT3 抑制剂增强 FLT3-ITD 对 AML 细胞凋亡的诱导 通过抗凋亡蛋白 Mcl-1 及其去泛素酶 USP9X 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 使用 PP2A 激活药物和 FLT3 抑制剂同时治疗 FLT3-ITD 细胞会导致 c-Myc 和 Pim-1 的翻译后下调；这些作用是由 AKT 介导的 GSK-3 失活依赖性激活，磷酸化 c-Myc 和 Pim-1，增强它们的活性 蛋白酶体降解。 该优异奖提案的总体假设是，与 PP2A 激活的同时治疗 药物或 Pim 激酶抑制剂可增强 FLT3 抑制剂在具有 FLT3-ITD 的 AML 中的疗效，废除或 延缓 FLT3 抑制剂耐药性的发展，并有可能使细胞对 FLT3 重新敏感 抑制剂耐药性通过多种机制发生。 我们的具体目标是： 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 抑制剂的功效； 2. 测试 PP2A激活药物或Pim抑制剂联合治疗在预防FLT3抑制剂耐药性方面的功效；和 3. 确定Pim抑制剂或PP2A激活药物联合治疗对AML细胞再敏化的疗效 FLT3-ITD 与 FLT3 抑制剂耐药性通过多种机制发生。 长期目标是开展临床试验，最终目标是改善治疗结果 患有 FLT3-ITD 的 AML 患者，FLT3-ITD 是一种常见的 AML 亚型，治疗效果不佳。