Liver-directed AAV gene therapy for PHKG2-Glycogen Storage Disease IX (GSD IX y2)

针对 PHKG2-糖原贮积病 IX (GSD IX y2) 的肝脏定向 AAV 基因治疗

• 批准号: 10315138
• 负责人: Rebecca Anne Gibson
• 金额: $ 3.82万
• 依托单位: DUKE UNIVERSITY
• 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 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10315138
• 关键词: Accounting; Address; Adolescent; Age-Months; Albumins; Blood Glucose; Breeding; Capsid; Case Study; Cells; Cessation of life; Child; Childhood; Cirrhosis; Clinical; Clinical Trials; Complex; Corn starch preparation; Data; Dependovirus; Diagnosis; Diet Modification; Dietary Intervention; Disease; Disease Progression; Disease model; Doctor of Philosophy; Dose; Enzymes; Female; Fibrosis; Future; Genes; Genetic; Glucose; Glycogen; Glycogen Storage Disease; Glycogen Storage Disease Type IX; Goals; Hepatocyte; Hepatomegaly; Human; Hypoglycemia; Immune response; Immunohistochemistry; Immunosuppression; Individual; Ketones; Knock-out; Knockout Mice; Laboratories; Life; Liver; Liver Failure; Liver Fibrosis; Liver Glycogen; Liver diseases; Mission; Modeling; Mus; National Institute of Child Health and Human Development; Pathway interactions; Patients; Phenotype; Phosphorylase Kinase; Physicians; Prevalence; Primary carcinoma of the liver cells; Protein Isoforms; Proteins; Public Health; Publishing; Quantitative Reverse Transcriptase PCR; Recombinant adeno-associated virus (rAAV); Reporting; Research; Risk; Scientist; Serotyping; Serum; Severities; Testing; Therapeutic; Time; Tissues; Transgenes; Tropism; Urine; Viral Vector; Weight; adeno-associated viral vector; base; bench to bedside; career; clinical translation; efficacy evaluation; enzyme activity; exome sequencing; gene therapy; glycogenolysis; high risk; in vivo; innovation; interdisciplinary collaboration; intravenous injection; liver function; liver injury; liver transplantation; male; minimally invasive; mouse model; novel; pre-clinical; preclinical efficacy; preclinical evaluation; promoter; symptomatic improvement; transduction efficiency; uncooked; vector

Liver Glycogen Storage Disease type IX has an overall estimated prevalence of 1 in 100,000 individuals, accounting for approximately 25% of all GSD cases. Liver GSD IX is caused by deficiency of the liver enzyme phosphorylase kinase (PhK) and presents with hepatomegaly, elevated liver enzymes, and hypoglycemia. PhK is a complex, hetero-tetrameric enzyme comprised of four subunits - α, β, γ, and δ - each with tissue specific isoforms encoded by different genes. The genes PHKA2, PHKB, and PHKG2 encode the liver specific isoform PhK subunits α2, β, and γ2 respectively. Until the recent availability of gene panels and exome sequencing, the diagnosis of Liver GSD IX did not allow for differentiation of these subtypes. There is growing evidence that patients with the second most common subtype, PHKG2 GSD IX (GSD IX γ2) develop severe liver disease. Of published case reports, 95.8% of patients with GSD IX γ2 reported features of liver fibrosis and/or cirrhosis, placing individuals with GSD IX γ2 at higher risk for liver failure, hepatocellular carcinoma and death. Despite the life-threatening severity of GSD IX γ2, there has been minimal research to understand disease progression or options for treatment. The first goal of this project is to characterize the phenotype of the first mouse model of PHKG2 GSD IX (GSD IX γ2). Preliminary evidence from male and female 3-month-old Phkg2-/- mice is encouraging. I have discovered that knockout mice have significantly elevated liver glycogen content, serum ALP, AST, ALT, urine Hex4, and features of hepatocyte enlargement and fibrosis compared to wild type controls. I will continue to characterize the Phkg2-/- mouse phenotype at 6, 9- and 12-months of age. By identifying the time of onset and progression of liver disease in our model, I will better understand the ideal time to deliver therapy. The second goal of this project is to evaluate the efficacy of a novel AAV gene therapy approach for reducing liver disease progression in the Phkg2-/- mouse model. Current liver-directed gene therapies utilize a recombinant adeno-associated virus serotype 8 (AAV8), based on preclinical efficacy in mice. However, recent studies have demonstrated that AAV8 has greater tropism for murine versus human hepatocytes. Our group has identified a novel capsid with high transduction rates for both human and murine hepatocytes (AAVhum.8) – making it an excellent vector for preclinical evaluation with high potential for clinical translation. The results of this project will characterize the first GSD IX γ2 mouse model, will provide preclinical evidence for a non-surgical, long-term, therapeutic option for patients with GSD IX γ2, and will inform the treatment of other pediatric genetic liver diseases.

IX 型肝糖原贮积病的总体估计患病率为十万分之一，约占所有 GSD 病例的 25%。肝脏 GSD IX 是由肝酶磷酸化酶激酶 (PhK) 缺乏引起的，表现为肝肿大、肝酶升高和低血糖。 PhK 是一种复杂的异源四聚体酶，由 α、β、γ 和 δ 四个亚基组成，每个亚基都具有由不同基因编码的组织特异性亚型。基因 PHKA2、PHKB 和 PHKG2 分别编码肝脏特异性亚型 PhK 亚基 α2、β 和 γ2。在最近出现基因组和外显子组测序之前，肝脏 GSD IX 的诊断无法区分这些亚型。越来越多的证据表明，第二种最常见亚型 PHKG2 GSD IX (GSD IX γ2) 的患者会出现严重的肝病。在已发表的病例报告中，95.8% 的 GSD IX γ2 患者报告有肝纤维化和/或肝硬化的特征，这使得 GSD IX γ2 患者发生肝衰竭、肝细胞癌和死亡的风险更高。尽管 GSD IX γ2 严重程度危及生命，但了解疾病进展或治疗选择的研究却很少。该项目的首要目标是表征第一个 PHKG2 GSD IX (GSD IX γ2) 小鼠模型的表型。来自 3 个月大的雄性和雌性 Phkg2-/- 小鼠的初步证据令人鼓舞。我发现与野生型对照相比，基因敲除小鼠的肝糖原含量、血清 ALP、AST、ALT、尿液 Hex4 显着升高，并且肝细胞增大和纤维化特征明显升高。我将继续表征 6、9 和 12 个月大的 Phkg2-/- 小鼠表型。通过在我们的模型中确定肝病的发病和进展时间，我将更好地了解提供治疗的理想时间。该项目的第二个目标是评估新型 AAV 基因治疗方法在 Phkg2-/- 小鼠模型中减少肝病进展的功效。目前的肝脏定向基因疗法利用重组腺相关病毒血清型 8 (AAV8)，基于小鼠的临床前疗效。然而，最近的研究表明，与人类肝细胞相比，AAV8 对小鼠肝细胞具有更大的趋向性。我们的小组已经鉴定出一种对人和鼠肝细胞具有高转导率的新型衣壳 (AAVhum.8)，使其成为临床前评估的优秀载体，具有很高的临床转化潜力。该项目的结果将表征第一个 GSD IX γ2 小鼠模型，将为 GSD IX γ2 患者的非手术长期治疗选择提供临床前证据，并将为其他儿科遗传性肝病的治疗提供信息。