Background

Fanconi anemia (FA) is a rare genetic disorder characterized by defective cellular DNA repair, associated developmental abnormalities, progressive bone marrow failure (BMF), and a predisposition to hematologic malignancies and solid tumors. 80% of FA patients develop BMF due to progressive depletion of their BM stem cells. Although allogeneic HSCT is a curative treatment for BMF, its utilization and efficacy is limited by availability of donors, risk of GVHD and transplant-related toxicities. Pre-clinical studies showed that ex-vivo insertion of a functional FANCA gene into autologous FA-A CD34+ HSPCs provides a survival advantage to the gene-modified stem cells, leading to correction of BMF. Feasibility of this approach was established in the FANCOLEN-1 clinical trial (Spain). Modifications to the collection and manufacturing processes were made in the Phase I study in the U.S.

Design and Methods

RP-L102-0418 (clinicaltrials.gov # NCT03814408) is a Phase I clinical trial evaluating the feasibility and safety of autologous CD34+ cells transduced with a lentiviral vector (LV) carrying the FANCA gene (PGK-FANCA-WPRE) in children with FA-A. Patients with early evidence of cytopenias, and with BM CD34+ count >30/µL were eligible for treatment. PBMCs were collected via leucocytapheresis after mobilization with G-CSF and Plerixafor. CD34+ HSPCs were enriched, placed in culture with cytokines, and transduced with PGK-FANCA-WPRE LV. The investigational drug product (DP) (RP-L102) was infused fresh in patients within 4 hours of release, without any conditioning regimen. Patients are being followed for safety assessments (replication competent lentivirus, insertion site analysis) and efficacy (increasing peripheral blood vector copy number and BM mitomycin-C resistance), along with monitoring of cytopenias.

Results

Two FA-A patients (aged 5 and 6 years) were consented and enrolled on the study at Stanford University. Mobilization and apheresis procedures were performed successfully without any serious adverse events. Both the patients needed RBC priming of the apheresis circuit because of their weight <20 kgs and developed thrombocytopenia post-apheresis. DP was successfully manufactured and infused in both the patients without any adverse events. 6 months post-infusion, the progressive cytopenias have stabilized. Detailed safety and efficacy data will be presented.

Conclusions

DP was successfully manufactured and infused in the Phase I study and both FA-A patients are showing early signs of stabilization of cytopenias. Plans for opening the Phase II study are in progress. Preventing BMF by gene therapy without any exposure to chemo-radiotherapy has the potential to change the natural history of FA.

中文翻译：

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用基因疗法改变范可尼贫血补体组的自然历史：美国慢病毒介导的前体FANCA基因在人干细胞和祖细胞中的美国I期研究的早期结果

背景

范可尼贫血（FA）是一种罕见的遗传性疾病，其特征是细胞DNA修复缺陷，相关的发育异常，进行性骨髓衰竭（BMF）以及血液系统恶性肿瘤和实体瘤的易感性。80％的FA患者由于其BM干细胞的逐渐消耗而发展为BMF。尽管同种异体HSCT是BMF的治疗方法，但其利用和功效受到供体可用性，GVHD风险和移植相关毒性的限制。临床前研究表明离体插入功能性FANCA将基因导入自体FA-A CD34 + HSPC中可为基因修饰的干细胞提供生存优势，从而可校正BMF。在FANCOLEN-1临床试验（西班牙）中确定了这种方法的可行性。在美国的第一阶段研究中对收集和制造过程进行了修改

设计与方法

RP-L102-0418（clinicaltrials.gov＃NCT03814408）是一项I期临床试验，评估携带FANCA基因（PGK-FANCA-WPRE）的慢病毒载体（LV）转导的慢病毒载体（LV）转导的自体CD34 +细胞的可行性和安全性-一种。早期有血细胞减少症证据，且BM CD34 +计数> 30 / µL的患者符合治疗条件。用G-CSF和Plerixafor动员后，通过白细胞清除术收集PBMC。富集CD34 + HSPC，将其与细胞因子一起培养，并用PGK-FANCA-WPRE LV转导。研究药物（DP）（RP-L102）在释放后的4小时内被新鲜注入患者，没有任何调理方案。对患者进行安全性评估（复制型慢病毒，插入位点分析）和疗效（增加外周血载体拷贝数和BM丝裂霉素-C耐药性），并监测血细胞减少症。

结果

两名FA-A患者（年龄分别为5岁和6岁）获得了同意，并被斯坦福大学纳入研究。动员和采血程序成功进行，没有任何严重的不良事件。两名患者均体重<20 kgs，需要进行红细胞灌注术，因为它们的体重<20 kgs，并且在放血后出现血小板减少症。两名患者均成功制造并输注了DP，无任何不良事件。输注后6个月，进行性血细胞减少症已稳定。将提供详细的安全性和有效性数据。

结论

DP在I期研究中成功制造并注入，两名FA-A患者均显示出血细胞减少症稳定的早期迹象。正在启动第二阶段研究的计划。通过基因疗法预防BMF而无需进行任何化学放射疗法的暴露，可能会改变FA的自然病史。