Background

Wiskott-Aldrich syndrome is a rare, life-threatening, X-linked primary immunodeficiency characterised by microthrombocytopenia, infections, eczema, autoimmunity, and malignant disease. Lentiviral vector-mediated haemopoietic stem/progenitor cell (HSPC) gene therapy is a potentially curative treatment that represents an alternative to allogeneic HSPC transplantation. Here, we report safety and efficacy data from an interim analysis of patients with severe Wiskott-Aldrich syndrome who received lentiviral vector-derived gene therapy.

Methods

We did a non-randomised, open-label, phase 1/2 clinical study in paediatric patients with severe Wiskott-Aldrich syndrome, defined by either WAS gene mutation or absent Wiskott-Aldrich syndrome protein (WASP) expression or a Zhu clinical score of 3 or higher. We included patients who had no HLA-identical sibling donor available or, for children younger than 5 years of age, no suitable 10/10 matched unrelated donor or 6/6 unrelated cord blood donor. After treatment with rituximab and a reduced-intensity conditioning regimen of busulfan and fludarabine, patients received one intravenous infusion of autologous CD34+ cells genetically modified with a lentiviral vector encoding for human WAS cDNA. The primary safety endpoints were safety of the conditioning regimen and safety of lentiviral gene transfer into HSPCs. The primary efficacy endpoints were overall survival, sustained engraftment of genetically corrected HSPCs, expression of vector-derived WASP, improved T-cell function, antigen-specific responses to vaccinations, and improved platelet count and mean platelet volume normalisation. This interim analysis was done when the first six patients treated had completed at least 3 years of follow-up. The planned analyses are presented for the intention-to-treat population. This trial is registered with ClinicalTrials.gov (number NCT01515462) and EudraCT (number 2009-017346-32).

Findings

Between April 20, 2010, and Feb 26, 2015, nine patients (all male) were enrolled of whom one was excluded after screening; the age range of the eight treated children was 1·1–12·4 years. At the time of the interim analysis (data cutoff April 29, 2016), median follow-up was 3·6 years (range 0·5–5·6). Overall survival was 100%. Engraftment of genetically corrected HSPCs was successful and sustained in all patients. The fraction of WASP-positive lymphocytes increased from a median of 3·9% (range 1·8–35·6) before gene therapy to 66·7% (55·7–98·6) at 12 months after gene therapy, whereas WASP-positive platelets increased from 19·1% (range 4·1–31·0) to 76·6% (53·1–98·4). Improvement of immune function was shown by normalisation of in-vitro T-cell function and successful discontinuation of immunoglobulin supplementation in seven patients with follow-up longer than 1 year, followed by positive antigen-specific response to vaccination. Severe infections fell from 2·38 (95% CI 1·44–3·72) per patient-year of observation (PYO) in the year before gene therapy to 0·31 (0·04–1·11) per PYO in the second year after gene therapy and 0·17 (0·00–0·93) per PYO in the third year after gene therapy. Before gene therapy, platelet counts were lower than 20 × 10⁹ per L in seven of eight patients. At the last follow-up visit, the platelet count had increased to 20–50 × 10⁹ per L in one patient, 50–100 × 10⁹ per L in five patients, and more than 100 × 10⁹ per L in two patients, which resulted in independence from platelet transfusions and absence of severe bleeding events. 27 serious adverse events in six patients occurred after gene therapy, 23 (85%) of which were infectious (pyrexia [five events in three patients], device-related infections, including one case of sepsis [four events in three patients], and gastroenteritis, including one case due to rotavirus [three events in two patients]); these occurred mainly in the first 6 months of follow-up. No adverse reactions to the investigational drug product and no abnormal clonal proliferation or leukaemia were reported after gene therapy.

Interpretation

Data from this study show that gene therapy provides a valuable treatment option for patients with severe Wiskott-Aldrich syndrome, particularly for those who do not have a suitable HSPC donor available.

Funding

Italian Telethon Foundation, GlaxoSmithKline, and Orchard Therapeutics.

中文翻译：

---

慢病毒造血干/祖细胞基因疗法治疗Wiskott-Aldrich综合征：一项非随机，开放标签，1/2期临床研究的中期结果

背景

Wiskott-Aldrich综合征是一种罕见的，威胁生命的，X连锁的原发性免疫缺陷，其特征是微血小板减少症，感染，湿疹，自身免疫和恶性疾病。慢病毒载体介导的造血干/祖细胞（HSPC）基因治疗是一种潜在的治疗方法，代表了同种异体HSPC移植的替代方法。在这里，我们报告了接受慢病毒载体衍生基因治疗的严重Wiskott-Aldrich综合征患者的中期分析的安全性和有效性数据。

方法

我们对患有严重Wiskott-Aldrich综合征的小儿患者进行了非随机的，开放标签的1/2期临床研究，其定义为WAS基因突变或Wiskott-Aldrich综合征蛋白（WASP）表达缺失或Zhu临床得分为3或更高。我们纳入的患者没有可用的HLA相同的同胞供体，或者对于5岁以下的儿童，没有合适的10/10匹配的无关供体或6/6无关的脐带血供体。在用利妥昔单抗和降低强度的白消安和氟达拉滨调理方案治疗后，患者接受了静脉输注经编码人WAS慢病毒载体基因修饰的自体CD34 +细胞的输注cDNA。主要安全终点是调节方案的安全性和慢病毒基因转移到HSPC中的安全性。主要功效终点为总体生存率，基因校正的HSPC的持续植入，载体衍生的WASP的表达，改善的T细胞功能，对疫苗的抗原特异性反应以及改善的血小板计数和平均血小板体积标准化。当接受治疗的前六名患者至少完成了3年的随访时，才进行此中期分析。提出了针对意向治疗人群的计划分析。该试验已在ClinicalTrials.gov（编号NCT01515462）和EudraCT（编号2009-017346-32）中进行了注册。

发现

在2010年4月20日至2015年2月26日之间，共招募了9例患者（均为男性），其中1例在筛查后被排除在外。八名接受治疗的儿童的年龄范围为1·1-12·4岁。在进行中期分析时（数据截止日期为2016年4月29日），中位随访时间为3·6年（范围为0·5-5·6）。总体生存率为100％。经过基因校正的HSPCs的移植成功并在所有患者中持续存在。WASP阳性淋巴细胞的比例从基因治疗前的中位数3·9％（范围1·8–35·6）增加到基因治疗后12个月的中位数66·7％（55·7–98·6），而WASP阳性血小板从19·1％（范围4·1-31·0）增加到76·6％（53·1-98·4）。体外T细胞功能正常化和成功终止免疫治疗的7例随访时间超过1年的患者成功停止了免疫球蛋白的补充，随后对疫苗的抗原特异性反应为阳性，表明免疫功能得到了改善。严重感染从基因治疗前一年的每患者观察年（PYO）的2·38（95％CI 1·44–3·72）下降到2005年每个PYO的0·31（0·04-1·11）。基因治疗后第二年，基因治疗后第三年每个PYO为0·17（0·00-0·93）。基因治疗前，血小板计数低于20×10 严重感染从基因治疗前一年的每患者观察年（PYO）的2·38（95％CI 1·44–3·72）下降到2005年每个PYO的0·31（0·04-1·11）。基因治疗后第二年，基因治疗后第三年每个PYO为0·17（0·00-0·93）。基因治疗前，血小板计数低于20×10 严重感染从基因治疗前一年的每患者观察年（PYO）的2·38（95％CI 1·44–3·72）下降到2005年每个PYO的0·31（0·04-1·11）。基因治疗后第二年，基因治疗后第三年每个PYO为0·17（0·00-0·93）。基因治疗前，血小板计数低于20×108名患者中有7名每升⁹ 在最后一次随访中，一名患者的血小板计数增加至每升20–50×10 ⁹，五名患者的血小板计数增加至每L 50–100×10 ⁹，并且超过100×10 ⁹每两名患者每升L，导致血小板输注的独立性和严重出血事件的发生。基因治疗后6例患者发生27例严重不良事件，其中23例（85％）为传染性（发热（3例5例），与器械相关的感染，包括败血症1例（3例4例）和肠胃炎，包括因轮状病毒引起的1例[2例中有3例]；这些主要发生在随访的前6个月。基因治疗后未报告对研究药物的不良反应，也未报告异常的克隆增生或白血病。

解释

这项研究的数据表明，基因疗法为患有严重Wiskott-Aldrich综合征的患者，尤其是那些没有合适的HSPC供体的患者提供了一种有价值的治疗选择。

资金

意大利Telethon基金会，GlaxoSmithKline和Orchard Therapeutics。