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)是成人常见的急性白血病类型，是一种重要的健康问题 退伍军人因其发病率高，治疗反应经常不佳而备受关注。内部串联 在AML细胞中存在FMS样酪氨酸激酶3(Flt3)受体酪氨酸激酶的重复(ITD)。 30%的患者，并与不良的治疗结果有关。Flt3抑制剂有活性，但反应 是有限的和短暂的，抗药性的快速发展是通过不同的机制发生的。 Flt3-ITD导致组成性的Flt3信号，该信号也是异常的。除了激活 野生型Flt3、Flt3-ITD信号激活的PI3K/AKT/mTOR和MEK/ERK/RAS通路 激活信号转导和转录激活(STAT)5，这在转录上上调 致癌丝氨酸苏氨酸激酶Pim-1。PIM-1直接参与细胞的增殖和抗凋亡 Flt3-ITD的作用，还可以磷酸化和稳定Flt3，促进STAT5信号转导 带有Flt3-ITD的细胞内的反馈环。携带Flt3-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(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，c-Myc或 PIM-1对携带Flt3-ITD的细胞具有抗增殖作用。此外，PP2A和Pim-1都调节c-Myc 翻译后。我们假设，异常信号通路的同时靶向将增强 Flt3抑制剂的疗效和防止对Flt3抑制剂的耐药性的发展，并克服耐药性。 获得性耐药机制包括Flt3基因点突变的发生 激酶结构域，一种依赖于Flt3的机制，以及RAS突变--一种不依赖于flt3的机制。 在对Flt3抑制剂耐药的Flt3-ITD细胞中，Pim激酶的表达也进一步上调。 我们在先前的VA优秀奖中的工作集中在PAN-Pim激酶抑制的细胞和分子效应上。 含Flt3-ITD的AML细胞。PIM抑制本身几乎没有作用，但增强了抗增殖和促进肿瘤生长的作用。 Flt3抑制剂和化疗药物对患有Flt3-ITD的细胞的凋亡作用。我们发现皮姆 抑制Flt3-ITD增强Flt3抑制剂诱导AML细胞凋亡的体内外研究 通过翻译后下调抗凋亡蛋白Mcl-1及其去泛素酶USP9X。我们 随后发现，翻译后c-Myc下调发生在这些变化之前。我们还发现 Flt3-ITD与PP2A激活药物和Flt3抑制剂同时处理细胞引起 翻译后c-Myc和Pim-1的下调；这些效应是由AKT介导的 依赖于GSK-3的失活激活可同时磷酸化c-Myc和PIM-1，增强其 蛋白酶体降解。 这项奖励方案的总体假设是，与PP2A激活同时治疗 药物或Pim激酶抑制剂增强Flt3抑制剂在伴有Flt3-ITD的AML中的疗效，取消或 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 抑制剂耐药的发生机制不同。 我们的具体目标是：1.检验PP2A激活药物和Pim激酶抑制剂的假说 通过GSK-3介导的翻译后c-Myc下调提高Flt3抑制剂的疗效；2.测试 PP2A激活剂或Pim抑制剂联合治疗在预防Flt3抑制剂耐药性方面的效果；以及 3.检测PIM抑制剂或PP2A激活剂联合作用对AML细胞再增敏的作用 Flt3-ITD与Flt3抑制剂耐药的发生机制不同。 长期目标是开发临床试验，最终目标是改善治疗结果 AML患者伴有Flt3-ITD，这是一种常见的AML亚型，治疗结果较差。