Improving T-cell therapies for neuroblastoma

描述（由申请人提供）：该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t细胞治疗针对神经母细胞瘤（NB）的治疗潜力。NB是儿童期最常见的恶性颅外肿瘤，高危患儿虽经强化治疗，预后仍较差。因此需要新的治疗策略。我们最近证明，epstein - barr病毒特异性ctl （ebv - ctl）的过继转移，通过基因修饰表达靶向神经母细胞表达的GD2的嵌合抗原受体（CAR），在循环中持续6周，并确定了4/8例难治性/复发性NB患者的客观肿瘤反应。由于现在很明显，肿瘤对CTL输注的反应与这些CTL的持续/扩增相关，我们提出了一种新的策略来改善过继性转移car - gd2 - ebv -CTL的生长。虽然ctl的体内扩增可以在急性淋巴细胞减少的宿主中完成，但对于大多数已经接受了大剂量化疗和放疗的难治/耐药NB患者来说，深度淋巴细胞减少可能具有过度毒性。此外，高剂量IL-2的施用显著增加了毒性，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 （IL-7）似乎耐受性良好，并产生初始CD4+和CD8+ T淋巴细胞的多克隆扩增，而Tregs没有明显增加，这表明该细胞因子可用于改善过继转移的ctl的持久性/扩增。不幸的是，由于一旦T细胞暴露于抗原刺激下，IL-7受体α (IL-7Ra)的表达会迅速下调，因此IL-7对体外扩增肿瘤导向的ctl的活性有限。我们发现基因转移可以在不影响其抗原特异性和效应物功能的情况下恢复EBV- ctl中的功能性IL-7Ra。基于这些数据，我们建议在临床前模型和I期临床试验中评估向难治性/复发NB患者输注共表达CAR-GD2和IL-7Ra的ebv - ctl是否安全扩展并持续响应il -7，以及这种工程化ctl是否具有抗肿瘤活性。

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.