Novel factor VIII variants for improved efficacy in gene therapy for hemophilia A

新型因子 VIII 变体可提高 A 型血友病基因治疗的疗效

• 批准号: 9027334
• 负责人: DENISE E SABATINO
• 金额: $ 42万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9027334
• 关键词: Address; Amino Acids; Animal Disease Models; B-domain-deleted factor VIII; Biochemical; Biological; Blood Circulation; Blood Coagulation Disorders; Blood Coagulation Factor; Canis familiaris; Capsid; Clinic; Clinical; Clinical Trials; Codon Nucleotides; Complementary DNA; DNA Sequence; Data; Dose; Engineering; F8 gene; Factor IX; Factor VIII; Gene Delivery; Gene Transfer; Goals; Hemophilia A; Hemophilia B; Hemorrhage; Human; Immune response; Immunity; Link; Liver; Mediating; Modeling; Modification; Mus; Muscle; Patients; Peptide Hydrolases; Performance; Process; Production; Property; Proteins; Role; Safety; Site; Testing; Therapeutic; Therapeutic Effect; Transgenes; Translating; Translations; Variant; Viral; Viral Packaging; Viral Vector; adeno-associated viral vector; antibody inhibitor; base; disease phenotype; gene therapy; immunogenicity; improved; in vivo; inhibitor/antagonist; male; mouse model; novel; preclinical study; prevent; public health relevance; success; transgene expression; vector

 DESCRIPTION (provided by applicant): Hemophilia is an X-linked bleeding disorder caused by a deficiency in the clotting factor protein factor VIII (FVIII) (hemophilia A, HA) or factor IX (FIX) (hemophilia B, HB) present in 1 in 5,000 males worldwide. Small amounts of clotting factor protein (>1% of normal) in the circulation provide substantial improvement of the disease phenotype. Preclinical studies of gene-based therapies for HB in dog models provided the basis for ongoing clinical trials using adeno-associated viral (AAV) vectors. These ongoing clinical trials demonstrated sustained expression of therapeutic levels of FIX. However, 80% of all hemophilia is due to FVIII deficiency, hemophilia A (HA). Gene therapy for HA presents three distinct challenges: (1) intrinsic properties of human FVIII (hFVIII) make it difficult to express compared to other proteins of similar size (2) the large size of the FVIII cDNA is prone to rearrangements which hampers AAV production and (3) high rates of anti-FVIII antibody (inhibitor) formation in patients following protein therapy. In earlier studies, AAV delivery of canine FVIII in HA dogs resulted in long-term dose-dependent expression of cFVIII that significantly improves the disease phenotype, however, the dose of AAV to achieve these goals remains relatively high. This high vector dose may be an obstacle to translating to humans since humans may have pre-existing immunity to AAV and thus may have an immune response to the AAV capsid upon AAV vector administration. We recently identified two novel human FVIII modifications that overcome the challenges of packaging the FVIII cDNA into AAV vectors and expressing hFVIII protein. First, a unique codon-optimized hFVIII DNA sequence expresses higher than wild type hFVIII but also packages more efficiently into AAV vectors. AAV packaging of this codon-optimized cDNA sequence results in a homogenous AAV vector that has a two-fold higher yield than wild type hFVIII. Second, variants of an intracellular protease cleavage recognition site in the hFVIII protein confer increased secretion and biological activity. We hypothesize that AAV delivery of these hFVIII variants will be therapeutic at lower AAV doses than native hFVIII, with no increases in immunogenicity over the currently used B-domain deleted FVIII constructs. The goal of this proposal is to determine the efficacy and safety of AAV delivery of these novel variants of hFVIII in unique hemophilia A mouse models (Specific Aim 1) and hemophilia A dog models (Specific Aim 2) that are both tolerant to human FVIII. These studies have the potential for success in reducing the AAV vector dose which will have a profound impact on avoiding the anti-AAV immune responses and on the long-term efficacy after AAV-mediated gene delivery of FVIII which will provide the necessary advances to translate this gene therapy approach for hemophilia A into the clinic.

 描述：血友病是由X连锁的流血障碍，由fiftiction因子蛋白质VIII III（Hemophilia a，ha）或因子IX（FIX）（固定）（Hemophilia b，Hb）在全球5,000个男性中有1个。循环中的蛋白质（> 1％的正常）在狗模型中基于基因的临床前疗法的临床前研究为持续的清除试验提供了使用adeno相关的载体的基础。固定。蛋白质治疗后的抗FVIII抗体（抑制剂）在较早的研究中。人类的障碍可能使HABE对AAV载体具有免疫反应。 Tyerd型HFVIII，但也更有效地包装到AAV媒介中。分泌和生物学活性。 hfviants ofviants ofviants ofviants ofviants ofviiiii的hfviants变体在独特的血友病A中（特定的目标1）和狗模型（特定的目标2），这两者都可以降低对AAV载体的耐受性。具有抗AAV的免疫反应和FVII的基因递送的基因递送将为这种基因疗法的诊所提供必要的进步。