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: 10681449
• 负责人: Ben J Samelson-Jones
• 金额: $ 73.86万
• 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/10681449
• 关键词: Affect; Antibodies; B-Lymphocytes; Biology; Blood; Blood Coagulation Disorders; Breeding; 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; Pharmaceutical Preparations; 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; canine model; cost; efficacy evaluation; enzyme replacement therapy; gene therapy; gene therapy clinical trial; improved; ineffective therapies; inhibitor; male; manufacture; 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.

A 型血友病 (HA) 是一种 X 连锁出血性疾病，由突变导致因子 VIII (FVIII) 缺乏所致 在F8基因中。该疾病影响全球 1:5,000 出生的男性。 FVIII 蛋白替代疗法是 可有效预防/控制出血，但约 30% 的患者会产生 FVIII 抑制剂（中和 同种抗体）使 FVIII 无效；因此，发病率和死亡率增加。免疫耐受 诱导 (ITI) 是根除抑制剂/恢复 FVIII 免疫耐受的唯一成功策略。伊蒂 治疗方案基于 FVIII 蛋白注射数月/数年，对约 60% 的病例有效，但高 成本（约 100 万/年）阻碍了其在发达国家之外的使用。因此，消除抑制剂的新方法 是迫切需要的。正在进行的不使用抑制剂的 HA 的 AAV 肝脏基因治疗临床试验结果如下： 治疗性FVIII。这些研究使用的是在 HEK-293 或 Sf9 细胞中制造的载体，它们的特性不同 基础生物学和临床结果。我们的中心假设是 AAV-FVIII 肝脏基因治疗是一种理想的治疗方法 ITI 方案基于我们在抑制剂 HA 狗中的概念验证报告（Finn 等人 Blood，2010）和新颖的 初步数据。我们将使用 2 种具有犬 F8 基因的新型独特高反应抑制剂 HA 狗模型 与最具挑战性的抑制剂患者群体相关的突变可能会受益于 AAV ITI。这 该提案的基本原理是，单次注射 AAV 肝脏基因疗法可以 (A) 有效根除 高效价抑制剂，(B) 在高反应 HA 狗中恢复和维持对 FVIII 的免疫耐受 (C) 持续的 FVIII 表达可改善抑制剂根除后的出血表型。这 具体目标是 目标 1：确定 AAV 基因治疗在诱导免疫耐受方面的功效 高反应 HA 狗模型。我们将推进在各地狗模型中测试 AAV 基因治疗的努力 几个不同的品种来定义与抑制剂根除动力学相关的因素（转基因 级别/持续时间）。目标 2：确定 rAAV-Sf9 衍生的 AAV-cFVIII 基因疗法治疗 ITI 的潜力 高响应 HA 狗模型。 AAV-Sf9 后 3 年后 FVIII 表达最近意外下降 HA 患者中的 FVIII 引起了对其耐久性的担忧。迄今为止，根本机制尚不清楚。我们 假设这可能是 Sf9 衍生载体和/或 FVIII 的组合。我们将在狗身上确定是否 AAV-Sf9 随着时间的推移影响 FVIII 表达水平及其根除抑制剂和诱导耐受的能力 至FVIII。目标 3：定义 AAV 介导的 ITI 的潜在机制。在这些新颖的狗模型中，我们将 表征特定 B 细胞，尤其是 T 调节细胞库和 AAV-ITI 后的功能，并 确定两种细胞系衍生载体系统中免疫耐受的潜在机制。成功的 该提案的完成将支持针对HA抑制剂患者的AAV肝脏基因治疗临床试验。能力 诱导免疫耐受的基因疗法可能与酶治疗的其他遗传疾病有关 替代疗法并因抗药物中和抗体而复杂化。