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。

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.