Anti-AAV Antibodies as an Obstacle to Cardiac AAV Gene Therapy

抗 AAV 抗体是心脏 AAV 基因治疗的障碍

• 批准号: 9281067
• 负责人: Roger J. Hajjar
• 金额: $ 82.14万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9281067
• 关键词: Address; Adsorption; Age; Animal Model; Antibodies; Antibody titer measurement; Antigens; Bacterial Transformation; Biological Assay; Blood; Bypass; Ca(2+)-Transporting ATPase; Calcium; Capsid; Cardiac; Cardiac Myocytes; Cardiovascular Diseases; Cells; Cessation of life; Clinic; Coronary; Coupled; Data; Dependovirus; Development; Diagnosis; Directed Molecular Evolution; Disease; Escherichia coli; Exclusion Criteria; Failure; Family suidae; Future; Gene Delivery; Gene therapy trial; Genes; Goals; Heart Diseases; Heart failure; Human; Immobilization; Immunoglobulins; In Vitro; Infusion procedures; Libraries; Methods; Mission; Modeling; National Heart, Lung, and Blood Institute; Nude Rats; Outcome; Patients; Percutaneous Administrations; Phase; Plasmapheresis; Protein Isoforms; Pump; Resistance; Rodent; SERCA2a; Sarcoplasmic Reticulum; Serotyping; Survival Rate; Techniques; Testing; Therapeutic; Treatment Efficacy; Tropism; Up-Regulation; Variant; Viral; Virion; Virus; adeno-associated viral vector; base; design; experimental study; gene therapy; improved; in vitro Assay; in vivo; innovation; lifetime risk; neutralizing antibody; novel; novel strategies; prevent; therapeutic gene; transgene expression; treatment strategy; vector

Recently, Adeno-Associated Virus (AAV)-based vectors have emerged as promising gene delivery vehicles for a wide array of diseases, including cardiovascular disorders. Despite early encouraging results, the CUPID (Calcium Upregulation by Percutaneous Administration of Gene Therapy in Cardiac Disease) trial using an AAV serotype 1 vector encoding the sarcoplasmatic calcium ATPase SERCA2a failed to meet both its primary and secondary endpoints. These results were surprising because in porcine models of HF AAV1.SERCA2a improved cardiac function. Preliminary results suggest that the disappointing outcome was due to a failure of AAV1.SERCA2a to deliver efficiently the SERCA2a gene. One possible explanation for the poor gene delivery is that neutralizing antibodies (NAbs) against AAV1 were not detected with the in vitro NAb assay used in the CUPID trial, but that these NAbs prevented transduction. In Aim 1 of this application we will test in a porcine HF model the hypothesis that extremely low levels of NAbs, which can only be detected by a more sensitive in vivo NAb assay, can prevent transduction and therapeutic efficacy of AAV1.SERCA2a. Conversely, if in vitro NAb assays are sufficiently sensitive, we will determine the maximal NAb levels that are still compatible with efficient transduction and therapeutic efficacy of AAV1.SERCA2a (in pigs). An alternative explanation for the negative results of the CUPID trial is that AAV1 displays specie-specific tropism, i.e. that AAV1 can efficiently transduce pig but not human cardiomyocytes. To bring cardiac AAV gene therapy to the clinic, it will be critical to isolate AAV variants that 1) Can efficiently transduce human cardiac cells and 2) Show increased resistance to NAbs. The isolation of such variants is the goal of Aim 2. Unfortunately, it seems unlikely that AAV variants that can efficiently transduce human cardiomyocytes and that are also resistant to very high levels of NAbs against the naturally occurring AAV serotypes can be isolated. Therefore, in Aim 3, we will test an approach to deplete NAbs from the blood by plasmapheresis coupled with immunadsorption with columns with immobilized AAV particles. With the successful completion of this proposal, we will have established whether an in vitro NAb assay is sensitive enough to serve as an exclusion criterion for cardiac AAV gene therapy trials where AAV is delivered by intracoronary infusion, or if a more sensitive in vivo assay must be used. We will have isolated novel AAV variants with tropism for human cardiomyocytes and increased resistance to NAbs. Finally, we will have established whether plasmapheresis coupled with immunadsorption on AAV columns can be used to deplete NAbs from blood. These parameters will be critical in the design and execution of future gene therapy trials for cardiovascular diseases.

最近，基于腺相关病毒（AAV）的载体已成为有前景的基因递送载体 用于治疗多种疾病，包括心血管疾病。尽管早期取得了令人鼓舞的成果， CUPID（心脏病基因治疗经皮给药的钙上调）试验使用 编码肌浆钙 ATP 酶 SERCA2a 的 AAV 血清型 1 载体未能满足其 主要和次要终点。这些结果令人惊讶，因为在 HF 猪模型中 AAV1.SERCA2a 改善心脏功能。初步结果表明，结果令人失望 由于 AAV1.SERCA2a 未能有效传递 SERCA2a 基因。一种可能的解释是 基因传递不良的原因是体外 NAb 未检测到针对 AAV1 的中和抗体 (NAb) CUPID 试验中使用了测定法，但这些 NAb 阻止了转导。在此应用程序的目标 1 中，我们将 在猪 HF 模型中测试了以下假设：NAb 水平极低，只能通过 体内NAb测定更加灵敏，可以阻止AAV1.SERCA2a的转导和治疗功效。 相反，如果体外 NAb 测定足够灵敏，我们将确定最大 NAb 水平 仍然与 AAV1.SERCA2a（在猪中）的高效转导和治疗功效兼容。 对 CUPID 试验负面结果的另一种解释是 AAV1 显示物种特异性 趋向性，即 AAV1 可以有效转导猪心肌细胞，但不能有效转导人心肌细胞。 为了将心脏 AAV 基因疗法引入临床，分离 AAV 变种至关重要：1) 有效转导人类心肌细胞，并且 2) 显示对 NAb 的抵抗力增强。此类隔离 变体是目标 2 的目标。 不幸的是，AAV 变体似乎不太可能有效转导人类心肌细胞 并且对针对天然存在的 AAV 血清型的非常高水平的 NAb 具有抵抗力 孤立。因此，在目标 3 中，我们将测试一种通过血浆去除术从血液中消耗 NAb 的方法 与带有固定 AAV 颗粒的柱的免疫吸附相结合。 随着该提案的成功完成，我们将确定体外 NAb 测定是否可行 足够敏感，可以作为使用 AAV 的心脏 AAV 基因治疗试验的排除标准 通过冠状动脉内输注，或者如果必须使用更灵敏的体内测定。我们将分离出新颖的 AAV 对人类心肌细胞具有趋向性并增加对 NAb 的抵抗力的变异体。最后，我们将有 确定血浆去除术与 AAV 柱上的免疫吸附相结合是否可用于消耗 来自血液的NAb。这些参数对于未来基因治疗试验的设计和执行至关重要 心血管疾病。