Batty P, Mo A M, Hurlbut D, Ishida J, Yates B, Brown C, Harpell L, Hough C, Pender A, Rimmer E K, Sardo Infirri S, Winterborn A, Fong S, Lillicrap D
Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada.
Vector Biology, BioMarin Pharmaceutical Inc, Novato, CA.
Blood. 2022 Dec 22;140(25):2672-2683. doi: 10.1182/blood.2021014735.
Questions remain concerning the long-term efficacy, safety, and site(s) of transgene expression following adeno-associated vector (AAV) therapy. We report a long-term follow-up of 8 (male = 4, hemizygous, and female = 4, homozygous) dogs with severe hemophilia A treated with a single portal vein infusion of a B-domain-deleted (BDD)-canine FVIII (cFVIII) AAV vector (median dose = 1.25 × 1013 vg/kg, AAV2 = 4, AAV6 = 3, and AAV8 = 1). After a median follow-up of 10.8 years (8.2-12.0 years), persistent FVIII:C (median one-stage = 12.7%, chromogenic = 7.2%) was seen in all responding dogs (n = 6), with improvement in annualized bleed rates (pre = 3.9 vs post = 0.3 event per year; P = .003). Anti-AAV capsid neutralizing antibodies (nAbs) toward the dosed capsid were detected throughout the study, with limited cross-reactivity to other capsids. nAb titers for all capsid serotypes declined with time, although they remained at levels precluding redosing with the same capsid. AAV-BDD-cFVIII DNA was detected in the liver of all dogs (median = 0.15 vg per diploid genome), with lower levels in the spleen in 4 dogs (median = 0.005 vg per diploid genome). Consistent with the liver-specific promoter, BDD-cFVIII mRNA was only detected in the liver. Postmortem examination demonstrated no evidence of chronic liver disease or liver malignancy. Persistent FVIII expression and an improved bleeding phenotype was seen for more than a decade after vector delivery. This is the longest follow-up reported in a preclinical model supporting long-term efficacy and safety of AAV-mediated gene therapy.
关于腺相关病毒（AAV）治疗后转基因表达的长期疗效、安全性及表达部位仍存在问题。我们报告了8只（雄性4只，半合子；雌性4只，纯合子）患有严重A型血友病的犬的长期随访情况，这些犬经门静脉单次输注B结构域缺失（BDD）的犬FVIII（cFVIII）AAV载体进行治疗（中位剂量 = 1.25×10¹³ vg/kg，AAV2 = 4只，AAV6 = 3只，AAV8 = 1只）。中位随访10.8年（8.2 - 12.0年）后，所有有反应的犬（n = 6）均出现持续的FVIII:C（中位一期法 = 12.7%，发色底物法 = 7.2%），年化出血率有所改善（治疗前 = 每年3.9次 vs 治疗后 = 每年0.3次；P = 0.003）。在整个研究过程中均检测到针对所用衣壳的抗AAV衣壳中和抗体（nAbs），与其他衣壳的交叉反应有限。所有衣壳血清型的nAb滴度均随时间下降，尽管仍处于阻止用相同衣壳再次给药的水平。在所有犬的肝脏中均检测到AAV - BDD - cFVIII DNA（中位值 = 每二倍体基因组0.15 vg），4只犬的脾脏中水平较低（中位值 = 每二倍体基因组0.005 vg）。与肝脏特异性启动子一致，仅在肝脏中检测到BDD - cFVIII mRNA。尸检未发现慢性肝病或肝恶性肿瘤的证据。载体递送十多年后仍可见持续的FVIII表达和改善的出血表型。这是在支持AAV介导的基因治疗长期疗效和安全性的临床前模型中报告的最长随访时间。
