Advancing fetal hemoglobin to the clinic using highly predictive in vivo strategies

项目摘要 胎儿血红蛋白水平升高可减轻镰状细胞病（SCD）的严重程度并延长寿命 病人。有效治疗美国和全球预计的大量SCD患者， 未来几年，最好是用一种负担得起的、容易服用的、口服的药物来实现 旨在将胎儿血红蛋白（HbF）水平提高到目标>30%的治疗，分布在整个大 红细胞百分比。羟基脲（HU）是目前FDA批准的唯一治疗SCD的药物， 在大约50%的患者中有效，并且HbF在以下患者中保持不均匀分布： 红细胞中，导致大部分缺乏HbF的保护作用。一个合理的方法来增加 我们实验室已经成功地研究了HbF干预表观遗传机制， 使用酶的药理学抑制剂在成人中执行从HbF到HbA表达的转换， 催化与γ-珠蛋白基因沉默相关的抑制性表观遗传修饰。本实验室 三十多年来，开发和利用了体内狒狒模型来研究珠蛋白基因调控， HbF诱导药物的体内活性。猿类灵长类，如狒狒，被广泛认为是 这是测试新药增加γ-珠蛋白表达能力的最佳动物模型， 由于HbF诱导剂的结构和发育的保守性， 类人猿β-珠蛋白基因的阶段特异性调节。我们实验室的初步研究 表明DNA甲基转移酶（DNMT）抑制剂增加狒狒的HbF， 许多临床试验证实了它们对SCD患者的有效性并验证了狒狒的使用 模型最近，我们发现LSD 1抑制剂RN-1增加了镰状细胞中γ-珠蛋白的表达， 在疾病小鼠模型和狒狒中，狒狒的长期治疗耐受良好。在这 我们将1）研究靶向DNMT 1和LSD 1两者的组合药物方案，以影响 HbF诱导和潜在不良血液学副作用的减少，2）继续推进新的 高度特异性的“第三代”LSD 1抑制剂，其通过血脑屏障的能力降低， 目标是将HbF增加至治疗水平，使F细胞数量最大化，并提高治疗指数，以及 3)研究单独扩增允许γ-珠蛋白表达的BFU-E亚群的新化合物 并与表观遗传修饰酶的抑制剂组合，用于额外刺激HbF诱导。 我们设想，这些研究的结果将直接影响新的临床试验的设计，以增加 用于治疗镰状细胞病的HbF。 OMB编号0925-0001/0002（2016年3月修订版，批准至2018年10月31日）

Project Summary Abstract Elevated fetal hemoglobin levels lessen the severity of sickle cell disease (SCD) and increase the lifespan of patients. Effective treatment of the large numbers of SCD patients projected in the U.S. and worldwide in the coming years would be best accomplished with an affordable, easily-administered, orally-available drug therapy designed to increase Fetal Hemoglobin (HbF) levels to a target >30% distributed throughout a large percentage of erythrocytes. Hydroxyurea (HU), currently the sole FDA-approved drug for SCD, is only effective in approximately 50% of patients and the HbF remains heterogeneously distributed among erythrocytes resulting in a large fraction lacking the protective effects of HbF. A logical approach to increase HbF that has been successfully pursued by our laboratory is to intervene with the epigenetic mechanism executing the switch from HbF to HbA expression in adults using pharmacological inhibitors of enzymes that catalyze repressive epigenetic modifications associated with γ-globin gene silencing. Our laboratory has developed and utilized an in vivo baboon model for over thirty years to investigate globin gene regulation and the in vivo activity of HbF-inducing drugs. Simian primates such as the baboon are widely acknowledged as the best animal models for testing the ability of new drugs to increase γ-globin expression because the activity of HbF-inducing agents is predictive of effects in man due to conservation of the structure and developmental stage-specific regulation of the β-like globin genes in simian primates. Initial studies from our laboratory demonstrating that DNA methyltransferase (DNMT) inhibitors increased HbF in baboons were followed by a number of clinical trials that confirmed their effectiveness in SCD patients and validated use of the baboon model. Recently we have shown that the LSD1 inhibitor RN-1 increased γ-globin expression in the sickle cell disease mouse model and in baboons and that long term treatment of baboons was well tolerated. In this proposal we will 1) investigate a combinatorial drug regimen targeting both DNMT1 and LSD1 for effects on HbF induction and reduction of potentially adverse hematological side-effects, 2) continue to advance new highly specific “third generation” LSD1 inhibitors with reduced ability to cross the blood brain barrier with the goal of increasing HbF to therapeutic levels, maximizing F cell numbers, and raising the therapeutic index, and 3) investigate new compounds that expand the BFU-E subpopulation permissive for γ-globin expression, alone and in combination with inhibitors of epigenetic-modifying enzymes, for additional stimulation of HbF induction. We envision that the results of these studies will directly impinge in the design of new clinical trials to increase HbF for the therapy of sickle cell disease. OMB No. 0925-0001/0002 (Rev. 03/16 Approved Through 10/31/2018) Page Continuation Format Page