Improving T-cell therapies for neuroblastoma

描述(申请人提供)：这个项目的目的是通过共表达肿瘤特异性嵌合抗原受体(CAR)和细胞因子受体来提高针对神经母细胞瘤(NB)的T细胞治疗的潜力。NB是儿童最常见的颅外恶性肿瘤，患有高危疾病的儿童尽管接受了密集的治疗，但预后仍然很差。因此，需要新的治疗策略。我们最近证实，过继转移EB病毒特异性CTL(EBV-CTL)，通过基因修饰表达针对神经母细胞表达的GD2的嵌合抗原受体(CAR)，在循环中持续6周，并在4/8例难治性/复发性NB患者中确定了客观的肿瘤反应。由于现在很明显，CTL输注的肿瘤反应与这些CTL的持续/扩张相关，我们提出了一种新的策略来促进过继转移的CAR-GD2-EBV-CTL的生长。虽然CTL的体内扩增可以在急性淋巴耗竭的宿主中完成，但对于大多数已经接受大剂量化疗和放射治疗的难治性/耐药的NB患者来说，长期淋巴耗竭可能会产生过度的毒性。此外，大剂量IL-2的应用显著增加了毒性并有利于抑制抗肿瘤CTL功能的调节性T细胞(Tregs)的扩增。与IL-2相比，重组IL-7(rIL-7)的耐受性良好，可多克隆扩增初始的CD4+和CD8+T淋巴细胞，而Tregs未见明显增加，提示该细胞因子可用于改善过继转移的CTL的持久性/扩张性。遗憾的是，IL-7在体外扩增的肿瘤导向的CTL上的活性有限，因为一旦T细胞暴露于抗原刺激，IL-7受体α(IL-7ra)的表达就会迅速下调。我们发现，基因转移可以在不影响EBV-CTL的抗原特异性和效应功能的情况下，恢复EBV-CTL的功能。基于这些数据，我们建议在临床前模型中，然后在I期临床试验中，评估共表达CAR-GD2和IL-7Ra的EBV-CTL注入难治性/复发NB患者后是否安全地扩展和持续应用rIL-7，以及这些工程化CTL是否具有抗肿瘤活性。 公共卫生相关性：我们已经成功地治疗了神经母细胞瘤患者，方法是用嵌合分子修饰他们自己的免疫细胞，以消除肿瘤细胞。在这个项目中，我们打算通过将这些细胞注入神经母细胞瘤患者体内时，通过促进它们的生长来增强它们的能力。

DESCRIPTION (provided by applicant): The intent of this project is to improve the therapeutic potential of T-cell therapy targeting neuroblastoma (NB) by co-expressing a tumor-specific chimeric antigen receptor (CAR) and a cytokine receptor. NB is the most common malignant extracranial tumor of childhood, and children with high-risk disease continue to have a poor outcome despite intensive therapy. New treatment strategies are therefore required. We have recently demonstrated that adoptive transfer of Epstein-Barr-virus-specific CTLs (EBV-CTLs), genetically modified to express a chimeric antigen receptor (CAR) targeting GD2 expressed by neuroblasts, persisted in the circulation for 6 weeks and determined objective tumor responses in 4/8 patients with refractory/relapsed NB. Since it is now evident that tumor responses to CTL infusions correlate with the persistence/expansion of these CTLs, we propose a new strategy to improve the growth of adoptively transferred CAR-GD2-EBV-CTLs. Although in vivo expansion of CTLs can be accomplished in the acutely lymphodepleted host, profund lymphodepletion may be excessively toxic to the majority of refractory/resistant NB patients who have already received significant doses of chemotherapy and radiation. Moreover, the administration of high-doses of IL-2 significantly contributes in increasing the toxicity and in favoring the expansion of regulatory T cells (Tregs) that inhibit the function of anti-tumor CTLs. In contrast to IL-2, the administration of recombinant IL-7 (rIL-7) seems well tolerated and produces polyclonal expansion of naive CD4+ and CD8+ T lymphocytes, without evident increase of Tregs, suggesting that this cytokine can be used to improve the persistence/expansion of adoptively transferred CTLs. Unfortunately, IL-7 has only limited activity on ex vivo expanded tumor-directed CTLs because the expression of IL-7 receptor alpha (IL-7Ra) is rapidly down-regulated once T cells are exposed to antigen stimulation. We found that gene transfer can be used to restore functional IL-7Ra in EBV- CTLs without affecting their antigen specificity and effector function. Based on these data, we propose to evaluate in a preclinical model and then in a phase I clinical trial whether EBV-CTLs co-expressing CAR-GD2 and IL-7Ra infused into refractory/relapsed NB patients safely expand and persist in response to the administration of rIL-7, and whether such engineered CTLs have anti-tumor activity. PUBLIC HEALTH RELEVANCE: We have had success in treating patients with neuroblastoma by using their own immune cells modified with a chimeric molecule that eliminate the tumor cells. In this project we intend to arm these cells to be more potent by improving their growth when infused into the patients with neuroblastoma.