Eltrombopag for the Treatment of Bone Marrow Failure Syndromes

艾曲波帕治疗骨髓衰竭综合征

• 批准号: 10699730
• 负责人: Andre LaRochelle
• 金额: $ 61.83万
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10699730
• 关键词: AML/MDS; Adverse event; Affect; Affinity; Age; Allogenic; American Society of Hematology; Androgens; Anemia; Aplastic Anemia; Autologous; Blood; Blood Platelets; Bone Marrow; Bone Marrow Examination; Bone marrow failure; Bypass; CD34 gene; CRISPR/Cas technology; Cell division; Cells; Cellularity; Cessation of life; Chemotherapy and/or radiation; Chromosome abnormality; Clinical; Clinical Trials; Collection; Colony-Forming Units Assay; Common Terminology Criteria for Adverse Events; Cytogenetics; DNA Double Strand Break; DNA Repair; DNA replication fork; Disease; Disease Progression; Donor person; Dose; Double Strand Break Repair; Dysplasia; E. coli bacteremia; Enrollment; Ethnic Origin; Evaluable Disease; Exhibits; Extracellular Domain; Failure; Fanconi Anemia Complementation Group A Protein; Fanconi Anemia pathway; Fanconi Anemia-BRCA Pathway; Fanconi' s Anemia; Fibrosis; Frequencies; Funding; Genes; Genetic; Genome Stability; Germ-Line Mutation; Hematological Disease; Hematology; Hematopoiesis; Hematopoietic; Hemoglobin; Hemorrhage; Human; Hypersensitivity; Immune; Immune mediated destruction; Impairment; In Vitro; Ineffective Hematopoiesis; Infection; Inflammation; Inflammation Mediators; Inflammatory; Inherited; Interferons; Interruption; Investigation; Iron; Iron Chelating Agents; Iron Overload; Karyotype determination procedure; Lead; Life; Malignant - descriptor; Marrow; Maximum Tolerated Dose; Mediating; Metaphase; Modality; Molecular; Monosomy 7; Morphology; Mus; Natural regeneration; Nonhomologous DNA End Joining; Oral; Outcome; PF4 Gene; Pathogenicity; Pathway interactions; Patients; Phase; Phase I/II Clinical Trial; Property; Publishing; Refractory; Regimen; Research; Research Personnel; Residual state; Safety; Sepsis; Series; Signal Pathway; Signal Transduction; Signal Transduction Inhibition; Solid Neoplasm; Specimen; Stem cell transplant; TNF gene; Testing; Therapeutic; Therapeutic immunosuppression; Thrombopoietin; Time; Toxic effect; Transplant Recipients; Transplantation; Work; bone marrow failure syndrome; clinical efficacy; clinically significant; conditioning; crosslink; cytopenia; disorder risk; improved; indexing; insight; iron supplementation; knock-down; loss of function mutation; member; mimetics; myeloblast; neutrophil; novel; novel therapeutics; patient response; peripheral blood; preclinical study; progenitor; prospective; receptor; replication stress; response; side effect; small molecule; stem cells

Objective 1: Characterize the mechanisms by which Epag promotes trilineage hematopoiesis. 1.1 Epag evades IFN blockade of signal transduction from c-MPL in human HSPCs To determine whether EPAG can offer a new therapeutic modality for hematopoietic regeneration in patients with IBMFS, we first sought to gain insights into the molecular mechanisms by which EPAG could enhance trilineage hematopoiesis in subjects with AA. Paradoxically, TPO levels are already markedly elevated in patients with severe AA; how adjunct therapy with the TPO mimetic EPAG could improve the stem cell deficit was thus a conundrum. Because marrow failure in AA largely results from the suppressive effects of IFN, we hypothesized that EPAG might support HSPC survival by activating signaling pathways in these cells distinctly from endogenous TPO under inflammatory conditions. To test this possibility, we directly compared the effect of IFN on human HSPCs in the presence of TPO or EPAG in vitro. We made two observations. First, we found that IFN perturbed TPO-induced signaling pathways in human HSPCs and that EPAG could bypass this inhibition, resulting in enhanced progenitor activity and long-term HSPC repopulating potential in the presence of IFN. Second, we showed that IFN disrupted the low-affinity interaction between TPO and the extracellular domain of c-MPL by forming TPO-IFN heteromers, delineating a novel molecular mechanism by which IFN inhibits TPO signaling in HSPCs. EPAG may bypass the inflammatory inhibition of signal transduction by avoiding capture by IFN in the BM, thus providing an explanation for its clinical efficacy in AA, despite already elevated levels of TPO in these patients. This work was published Blood 133:2043-55 (2019). 1.2 Epag promotes DNA DSB repair in human HSPCs. To further elucidate the mechanisms by which EPAG improves hematopoiesis and assess its therapeutic potential in FA, we investigated whether EPAG could promote DNA repair in human HSPCs. We demonstrated that EPAG specifically activated the classical non-homologous end joining (C-NHEJ) DNA DSB repair mechanism, a pathway known to support genomic stability, in both normal human HSPCs and donor HSPCs subjected to CRISPR/Cas9-mediated knockdown of FANCA. Importantly, EPAG-mediated DNA repair resulted in enhanced genomic stability, survival, and function of primary human HSPCs, as demonstrated in karyotyping analyses, colony-forming unit (CFU) assays and after transplantation into immunodeficient NSG mice. This work was published Exp Hematol 73:1-6 (2019). Objective 2: Evaluate the safety and efficacy of Epag in subjects with Fanconi anemia. The ability of EPAG to stimulate multipotent long-term repopulating HSPCs in patients with AA, to maintain HSPCs under inflammatory conditions and to promote DNA repair in these cells suggested potential therapeutic relevance in FA-associated BMF. We have initiated an investigator-sponsored prospective phase I/II clinical trial of EPAG in Fanconi anemia (NCT03204188) and enrolled 14 patients to date (FANCA, n=12 and FANCC, n=2). One subject withdrew early after identifying a suitable matched donor for transplant. All other subjects received EPAG at an oral daily dose adjusted for age and ethnicity. The primary efficacy endpoint was the proportion of subjects with at least 2-fold increase in marrow cellularity or CD34+ HSPC frequency (marrow response), or clinically significant improvement in peripheral blood (PB) counts at 6 months (blood response). The primary safety endpoint was the global toxicity profile assessed at 6 months using CTCAE criteria. Responders were invited to continue EPAG on an extension phase of the study for an additional 3 years. Ten of the 13 evaluable patients have reached the 6-month assessment endpoint. A marrow response was observed in 9 subjects at 6 months; the marrow specimens were of poor quality at baseline and 6 months for one patient and response assessment could not be performed. Mean marrow cellularity increased by a factor of 4.1, and CD34+ HSPC frequency improved 1.6-fold at 6 months relative to pre-treatment values. Primary PB response was observed in 7 of 10 patients in one (hemoglobin, n=4) or two lineages (hemoglobin and platelets, n=3) at 6 months of treatment. One patient who had a marrow but no PB response underwent an unrelated allogeneic HSPC transplantation and is clinically well. The other nine subjects received EPAG on the extension phase of the study (range, 12 to 40 months) with stable or improving blood counts. One patient who had stable but no increase in PB counts at 6 months displayed a unilineage response at 12 months and three subjects met criteria for trilineage response at 9, 21 and 24 months, respectively. All evaluable patients tolerated the maximum dose of EPAG and no interruption or dose reduction was required for adverse events attributable to EPAG. Patients without transfusional iron overload at study entry developed progressive depletion of iron stores attributable to the known potent iron chelating and mobilizing properties of EPAG. At a median of 3 months after initiating EPAG (range, 1 to 6 months), affected patients initiated daily oral iron supplementation with gradual amelioration of iron depletion. To date, there has been no occurrence of marrow fibrosis, solid tumors or overt clinical transformation to MDS/AML. However, we recently observed monosomy 7 on standard metaphase analysis in one subject treated with EPAG for 12 months. There was no associated morphologic dysplasia or increased myeloblasts. Several studies have recognized cytogenetic abnormalities on BM examination of untreated FA patients, many of them noting a high frequency of monosomy 7; thus, attribution of aberrant cytogenetics to EPAG cannot be confirmed in this patient. Nevertheless, given the well-documented association between monosomy 7 and increased risk for disease progression, EPAG was discontinued and he underwent an allogeneic stem cell transplantation. He is clinically well. One subject who had no improvement in neutrophil counts developed Escherichia coli bacteremia and sepsis-related death occurred after 13 months of treatment with eltrombopag. This work was presented at the American Society of Hematology (ASH 2019, ASH 2021) and the Fanconi Anemia Research Funds (FARF 2021, FARF 2022).

目标 1：表征 Epag 促进三系造血的机制。 1.1 Epag逃避IFN对人HSPC中c-MPL信号转导的阻断 为了确定 EPAG 是否可以为 IBMFS 患者的造血再生提供新的治疗方式，我们首先试图深入了解 EPAG 增强 AA 受试者三系造血的分子机制。矛盾的是，严重 AA 患者的 TPO 水平已经显着升高；因此，TPO 模拟 EPAG 的辅助治疗如何改善干细胞缺陷是一个难题。由于 AA 的骨髓衰竭很大程度上是由 IFN 的抑制作用造成的，因此我们假设 EPAG 可能通过激活这些细胞中的信号通路来支持 HSPC 的存活，这与炎症条件下的内源性 TPO 不同。为了测试这种可能性，我们在体外直接比较了 TPO 或 EPAG 存在下 IFN 对人 HSPC 的影响。我们提出了两个观察结果。首先，我们发现 IFN 扰乱了人类 HSPC 中 TPO 诱导的信号通路，而 EPAG 可以绕过这种抑制，从而在 IFN 存在的情况下增强祖细胞活性和长期 HSPC 重新增殖的潜力。其次，我们发现 IFN 通过形成 TPO-IFN 异聚体破坏了 TPO 与 c-MPL 胞外结构域之间的低亲和力相互作用，描绘了 IFN 抑制 HSPC 中 TPO 信号传导的新分子机制。 EPAG 可能通过避免被 BM 中的 IFN 捕获而绕过信号转导的炎症抑制，从而解释其在 AA 中的临床疗效，尽管这些患者的 TPO 水平已经升高。这项工作发表于 Blood 133:2043-55 (2019)。 1.2 Epag促进人类HSPC中的DNA DSB修复。 为了进一步阐明 EPAG 改善造血的机制并评估其在 FA 中的治疗潜力，我们研究了 EPAG 是否可以促进人类 HSPC 中的 DNA 修复。我们证明，在正常人 HSPC 和接受 CRISPR/Cas9 介导的 FANCA 敲低的供体 HSPC 中，EPAG 特异性激活经典的非同源末端连接 (C-NHEJ) DNA DSB 修复机制，这是一种已知支持基因组稳定性的途径。重要的是，EPAG 介导的 DNA 修复导致原代人类 HSPC 的基因组稳定性、存活率和功能增强，如核型分析、集落形成单位 (CFU) 测定以及移植到免疫缺陷 NSG 小鼠后所证明的那样。这项工作发表于 Exp Hematol 73:1-6 (2019)。 目标 2：评估 Epag 在范可尼贫血受试者中的安全性和有效性。 EPAG 能够刺激 AA 患者中的多能长期 HSPC 重新增殖、在炎症条件下维持 HSPC 并促进这些细胞中的 DNA 修复，这表明 FA 相关 BMF 具有潜在的治疗意义。我们启动了一项由研究者资助的 EPAG 治疗 Fanconi 贫血的前瞻性 I/II 期临床试验 (NCT03204188)，迄今为止已入组 14 名患者（FANCA，n=12 和 FANCC，n=2）。一名受试者在找到合适的移植捐献者后提前退出。所有其他受试者均接受根据年龄和种族调整的每日口服剂量的 EPAG。主要疗效终点是骨髓细胞构成或 CD34+ HSPC 频率至少增加 2 倍（骨髓反应），或 6 个月时外周血 (PB) 计数有临床显着改善（血液反应）的受试者比例。主要安全终点是使用 CTCAE 标准在 6 个月时评估的总体毒性特征。响应者被邀请继续 EPAG 的研究扩展阶段 3 年。 13 名可评估患者中有 10 名已达到 6 个月评估终点。 6 个月时，9 名受试者观察到骨髓反应；一名患者的骨髓标本在基线和 6 个月时质量较差，无法进行疗效评估。与治疗前相比，6 个月时平均骨髓细胞构成增加了 4.1 倍，CD34+ HSPC 频率提高了 1.6 倍。在治疗 6 个月时，在 10 名患者中的 7 名观察到一种（血红蛋白，n = 4）或两种谱系（血红蛋白和血小板，n = 3）的主要 PB 反应。一名有骨髓但无 PB 反应的患者接受了无关的同种异体 HSPC 移植，临床状况良好。其他 9 名受试者在研究的延长阶段（范围为 12 至 40 个月）接受了 EPAG，血细胞计数稳定或有所改善。一名 6 个月时 PB 计数稳定但未增加的患者在 12 个月时表现出单系反应，三名受试者分别在 9、21 和 24 个月时符合三系反应标准。 所有可评估的患者均耐受 EPAG 的最大剂量，并且无需因 EPAG 引起的不良事件而中断或减少剂量。在研究开始时没有输血铁超负荷的患者由于 EPAG 已知的强效铁螯合和动员特性而出现铁储备逐渐耗尽。开始 EPAG 后平均 3 个月（范围为 1 至 6 个月），受影响的患者开始每日口服铁补充剂，铁缺乏情况逐渐改善。迄今为止，尚未发生骨髓纤维化、实体瘤或明显的MDS/AML临床转化。然而，我们最近在接受 EPAG 治疗 12 个月的一名受试者的标准中期分析中观察到单体 7。没有相关的形态发育不良或成髓细胞增多。一些研究已经认识到未经治疗的 FA 患者的 BM 检查存在细胞遗传学异常，其中许多研究指出 7 号单体的频率较高；因此，在该患者中无法确认异常细胞遗传学是否归因于 EPAG。尽管如此，鉴于 7 号单体与疾病进展风险增加之间的关联已得到充分证实，EPAG 被终止，他接受了同种异体干细胞移植。他的临床状况良好。使用艾曲波帕治疗 13 个月后，一名中性粒细胞计数没有改善的受试者出现了大肠杆菌菌血症，并发生了败血症相关的死亡。这项工作已在美国血液学会（ASH 2019、ASH 2021）和范可尼贫血研究基金（FARF 2021、FARF 2022）上发表。