BACKGROUND Adeno-associated virus (AAV)-mediated gene therapy is under investigation as a therapeutic option for persons with hemophilia A. Efficacy and safety data include 3 years of follow-up after a single administration of AAV5-hFVIII-SQ. METHODS We report durable efficacy, long-term safety, and clinical and biologic results in 15 adults with severe hemophilia A (factor VIII level, ≤1 IU per deciliter) who had received a single infusion of AAV5-hFVIII-SQ at various dose levels. We evaluated the factor VIII level, annualized rate of bleeding events, use of factor VIII, safety, expression kinetics, and biologic markers of AAV transduction for up to 3 years. RESULTS Three years after infusion, two participants (one who had received 6×1012 vector genomes [vg] per kilogram of body weight and one who had received 2×1013 vg per kilogram) had factor VIII expression of less than 1 IU per deciliter, as assessed on chromogenic assay. Seven participants (who had received 6×1013 vg per kilogram) had a median factor VIII expression of 20 IU per deciliter; the median number of annualized treated bleeding events was 0, and the median use of exogenous factor VIII was reduced from 138.5 infusions to 0 infusions per year. Bleeding in all target joints (major joints with ≥3 bleeding events within 6 months) in this cohort resolved (≤2 bleeding events within 12 months). Two years after infusion, six participants (who had received 4×1013 vg per kilogram) had a median factor VIII expression of 13 IU per deciliter; the median annualized rate of bleeding events was 0, and the median use of factor VIII was reduced from 155.5 infusions to 0.5 infusions per year. Bleeding in target joints resolved in five of six participants. The factor VIII pharmacodynamic profiles reflected cellular turnover in the blood and molecular events leading to episomal DNA stabilization for persistent expression, findings that are consistent with previous observations in two model systems. Transgene-derived human factor VIII (hFVIII) protein activity mirrored native hFVIII in hemostatic ability. No inhibitor development, thromboses, deaths, or persistent changes in liver-function tests were observed. CONCLUSIONS Gene therapy with AAV5-hFVIII-SQ vector in participants with hemophilia A resulted in sustained, clinically relevant benefit, as measured by a substantial reduction in annualized rates of bleeding events and complete cessation of prophylactic factor VIII use in all participants who had received 4×1013 vg per kilogram or 6×1013 vg per kilogram of the gene therapy. (Funded by BioMarin Pharmaceutical; ClinicalTrials.gov number, NCT02576795; EudraCT number, 2014-003880-38.).

中文翻译：

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AAV5-hFVIII-SQ基因治疗A型血友病的多年随访

背景技术腺相关病毒（AAV）介导的基因治疗正在研究作为A型血友病患者的治疗选择。疗效和安全性数据包括单次服用AAV5-hFVIII-SQ后的3年随访。方法我们报告了15例严重A型血友病（因子VIII水平，≤1 IU每分升）的成人的持久疗效，长期安全性以及临床和生物学结果，这些成年人接受了不同剂量水平的AAV5-hFVIII-SQ单次输注。我们评估了长达三年的VIII因子水平，出血事件的年化率，VIII因子的使用，安全性，表达动力学和AAV转导的生物学标记。结果输注三年后，根据显色分析评估，两名参与者（每公斤体重接受6×1012 vg的人，而每公斤体重接受2×1013 vg的人）的VIII因子表达低于每分升1 IU。七名参与者（每公斤接受6×1013 vg）的VIII因子中位数表达为每分升20 IU。每年治疗出血事件的中位数为0，每年使用外源性因子VIII的中位数从138.5输注减少到0输注。在该队列中所有目标关节（6个月内≥3次出血事件的主要关节）出血得到解决（12个月内≤2次出血事件）。输注两年后，六名参与者（每公斤接受4×1013 vg）的VIII因子中位数表达为每分升13 IU。平均每年出血事件的发生率为0，并且将VIII因子的使用中位数从155.5输注减少到每年0.5输注。在六名参与者中的五名中，目标关节的出血得以解决。VIII因子的药效学特征反映了血液中的细胞更新和分子事件，导致游离DNA稳定表达以实现持续表达，这一发现与先前在两个模型系统中的观察结果一致。转基因来源的人类因子VIII（hFVIII）蛋白活性在止血能力方面反映了天然hFVIII。在肝功能检查中未观察到抑制剂形成，血栓形成，死亡或持续变化。结论AAV5-hFVIII-SQ载体对A型血友病参与者的基因治疗可产生持续的，与临床相关的益处，通过以每年每公斤接受4×1013 vg或每公斤6×1013 vg接受基因治疗的所有参与者的出血事件的年发生率大幅降低和完全停止使用预防性VIII因子来衡量。（由BioMarin Pharmaceutical资助; ClinicalTrials.gov编号，NCT02576795; EudraCT编号，2014-003880-38。）