Improving T-cell therapies for neuroblastoma

描述（由申请人提供）：本项目旨在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靶向神经母细胞瘤（NB）的T细胞治疗的治疗潜力。NB是儿童期最常见的恶性颅外肿瘤，尽管进行了强化治疗，但患有高危疾病的儿童的预后仍然很差。因此，需要新的治疗策略。我们最近已经证明，Epstein-Barr病毒特异性CTL（EBV-CTL）的过继转移，经遗传修饰以表达靶向神经母细胞表达的GD 2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患者中确定了客观肿瘤应答。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转移的CAR-GD 2-EBV-CTL的生长。虽然CTL的体内扩增可以在急性淋巴细胞耗竭的宿主中完成，但是对于已经接受显著剂量的化疗和放疗的大多数难治性/耐药NB患者，深度淋巴细胞耗竭可能具有过度毒性。此外，施用高剂量的IL-2显著地有助于增加毒性和有利于抑制抗肿瘤CTL功能的调节性T细胞（TCLs）的扩增。与IL-2相反，重组IL-7（rIL-7）的施用似乎耐受良好，并且产生幼稚CD 4+和CD 8 + T淋巴细胞的多克隆扩增，而没有明显的TcR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，IL-7对离体扩增的肿瘤定向CTL仅具有有限的活性，因为一旦T细胞暴露于抗原刺激，IL-7受体α（IL-7 Ra）的表达迅速下调。我们发现基因转移可用于恢复EBV-CTL中的功能性IL-7 Ra而不影响其抗原特异性和效应子功能。基于这些数据，我们建议在临床前模型中，然后在I期临床试验中评估输注到难治性/复发性NB患者中的共表达CAR-GD 2和IL-7 Ra的EBV-CTL是否安全地扩增并持续响应rIL-7的施用，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.