Immune tolerance induction by AAV-FVIII gene therapy for canine hemophilia A with inhibitors

AAV-FVIII 基因疗法对犬 A 型血友病抑制剂的免疫耐受诱导

• 批准号: 10276571
• 负责人: Valder R. Arruda
• 金额: $ 74.62万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10276571
• 关键词: Affect; Antibodies; B-Lymphocytes; Biology; Blood; Blood Coagulation Disorders; Canis familiaris; Catheters; Cell Line; Cells; Clinical; Clinical Trials; Data; Development; Disease; Dose; F8 gene; Factor VIII; Gene Mutation; Gene Transfer; Genetic Diseases; Goals; Hemophilia A; Hemorrhage; Hepatotoxicity; Human; Immune; Immune Tolerance; Immune response; Infusion procedures; Injections; Isoantibodies; Kinetics; Link; Liver; Maintenance; Measures; Mediating; Modeling; Morbidity - disease rate; Mutation; Other Genetics; Outcome; Patients; Phenotype; Prophylactic treatment; Proteins; Protocols documentation; Publishing; Recombinant adeno-associated virus (rAAV); Regimen; Regulatory T-Lymphocyte; Replacement Therapy; Reporting; Residual state; Role; Safety; Serotyping; Sf9 cell line; Study models; System; Testing; Therapeutic; Time; Transgenes; Venous; adeno-associated viral vector; base; cost; enzyme replacement therapy; gene therapy; gene therapy clinical trial; improved; ineffective therapies; inhibitor/antagonist; male; manufacturing process; mortality; neutralizing antibody; novel; novel strategies; prevent; restoration; success; therapeutic protein; vector

Hemophilia A (HA) is an X-linked bleeding disorder caused by a deficiency in factor VIII (FVIII) due to mutations in the F8 gene. The disease affects 1:5,000 male born worldwide. Replacement therapy with FVIII protein is effective in preventing/controlling bleeding but ~30% of patients develop inhibitors to FVIII (neutralizing alloantibodies) that renders FVIII ineffective; thus, increasing morbidity and mortality. Immune tolerance induction (ITI) is the only successful strategy for eradication of inhibitors/restore immune tolerance to FVIII. ITI regimens are based on FVIII protein injections for months/years and is efficacious in ~60% of cases, but the high cost (~1million/year) prevents its use outside the developed word. Thus, new approaches for inhibitor eradication are urgently needed. Ongoing AAV liver gene therapy clinical trials for HA without inhibitors resulted in therapeutic FVIII. These studies are using vectors manufactured in either HEK-293 or Sf9 cells that differ in their basic biology and clinical outcomes. Our central hypothesis is that AAV-FVIII liver gene therapy is an ideal ITI regimen based on our proof-of-concept report in inhibitor HA dogs (Finn et al Blood, 2010) and novel preliminary data. We will use 2 novel distinct high-responding inhibitor HA dog models with the canine F8 gene mutations associated with the most challenging inhibitor patient group that likely would benefit from AAV ITI. The rationale of this proposal is that a single injection of AAV liver gene therapy provides (A) efficient eradication of high titer inhibitors, (B) restoration and maintenance of immune tolerance to FVIII in high responding HA dogs and (C) continuous FVIII expression that improves the bleeding phenotype after inhibitor eradication. The specific aims are Aim 1: Determine the efficacy of AAV gene therapy in inducing immune tolerance in high-responding HA dog models.We will advance our efforts testing AAV gene therapy in dog models across several distinct breeds to define the factors associated with kinetics of inhibitor eradication (transgene levels/duration). Aim 2: Determine the potential of ITI by rAAV-Sf9-derived AAV-cFVIII gene therapy in high-responding HA dog models. Recent unexpected decline of FVIII expression after 3 years post- AAV-Sf9- FVIII in HA patients raised concerns of durability. To date, the underlying mechanism is unknown. We hypothesized that this could be a combination of Sf9-derived vector and/or FVIII. We will determine in dogs if AAV-Sf9 impacts FVIII expression levels over time and its ability to eradicate inhibitors and to induce tolerance to FVIII. Aim 3: Define the mechanism(s) underlying AAV-mediated ITI. In these novel dog models, we will characterize specific B cells and especially T regulatory cells pool and function following AAV-ITI and to determine the underlying mechanism of immune tolerance in both cell line-derived vector systems. Successful completion of this proposal would support AAV liver gene therapy clinical trial for inhibitor HA patients. The ability of gene therapy to induce immune tolerance is likely to be relevant to other genetic diseases treated with enzyme replacement therapy and complicated by antidrug neutralizing antibodies.

血友病A（HA）是由于突变引起的因子VIII（FVIII）缺乏引起的X连锁出血障碍 在F8基因中。该疾病影响着1：5,000名在全球出生的男性。用FVIII蛋白替代疗法是 有效预防/控制出血，但约有30％的患者会产生抑制剂（中和 同种抗体）使FVIII无效；因此，增加发病率和死亡率。免疫耐受性 诱导（ITI）是消除抑制剂/对FVIII的免疫耐受性的唯一成功策略。 iti 方案基于FVIII蛋白注射数月/年，在约60％的病例中有效，但高 成本（约100万/年）阻止其在发达的单词之外使用。因此，消除抑制剂的新方法 迫切需要。正在进行的AAV肝基因治疗无抑制剂的HA的临床试验导致 治疗性FVIII。这些研究使用在HEK-293或SF9细胞中生产的载体，其它们的不同 基本的生物学和临床结果。我们的中心假设是AAV-FVIII肝基因治疗是理想的 ITI方案基于我们在抑制剂HA狗（Finn等人，2010年）和新颖的概念验证报告 初步数据。我们将使用犬F8基因的2种新型的不同的高反应抑制剂HA狗模型 与最具挑战性的抑制剂患者组相关的突变可能会受益于AAV ITI。这 该提案的理由是单一注射AAV肝基因疗法可提供（a）有效地消除 高滴度抑制剂，（b）恢复和维持对高反应HA狗FVIII的免疫耐受性 （c）消除抑制剂后改善出血表型的连续FVIII表达。这 特定目的是目标1：确定AAV基因治疗在诱导免疫耐受性中的功效 高响应的HA狗模型。我们将促进我们在狗模型中测试AAV基因疗法的努力 几种不同的品种来定义与消除抑制剂动力学相关的因素（转基因 水平/持续时间）。 AIM 2：通过RAAV-SF9衍生的AAV-CFVIII基因疗法确定ITI的潜力 高响应HA狗模型。 AAV-SF9- 3年后，FVIII表达的最近出乎意料的下降 HA患者的FVIII引起了人们对耐用性的关注。迄今为止，基本机制尚不清楚。我们 假设这可能是SF9衍生的向量和/或FVIII的组合。我们将在狗中确定是否 AAV-SF9会影响FVIII的表达水平，并且其消除抑制剂的能力并诱导公差 到FVIII。目标3：定义AAV介导的ITI的基础机制。在这些新颖的狗模型中，我们将 表征特定的B细胞，尤其是T调节细胞池并在AAV-ITI之后起作用， 确定两个细胞系衍生的矢量系统中免疫耐受性的潜在机制。成功的 该建议的完成将支持抑制剂HA患者的AAV肝基因治疗临床试验。能力 诱导免疫耐受性的基因疗法可能与用酶治疗的其他遗传疾病有关 替代疗法，抗体中和抗体复杂。