Protection from GVHD with Gene-Modified Donor T Cells

描述(由申请人提供)：该项目的总体目标是开发一种有效的策略来管理严重的移植物抗宿主病(GVHD)，同时保护捐赠者的T细胞活性。异基因造血干细胞移植(HSCT)后，供者T细胞有助于预防移植物排斥反应和复发(GVH效应)以及免疫恢复，但会引起GVHD。目前的全球艾滋病毒/艾滋病管理战略没有充分处理这些相互竞争的终点。经修饰表达单纯疱疹病毒/胸苷激酶基因(HSV/TK；自杀基因)的同种异体反应性供者T细胞可维持体内功能(GVH效应)，并可被更昔洛韦诱导为“自毁”，以防止严重GVHD的发生。从表达HSV/TK基因的转基因小鼠进行的HSCT的临床前研究表明，GVHD在接受更昔洛韦治疗后得到控制，移植后没有发生排斥反应。由于未诱导未分裂的非同种异体反应性T细胞凋亡，因此提高了免疫重建能力。然而，到目前为止，转基因小鼠的研究还没有反映出临床经验。在临床试验中，人T细胞必须在体外用有丝分裂的CD3单抗进行体外扩增后，用逆转录病毒载体转导。在这些试验中，存在同种异体反应性的显著丧失，这否定了任何潜在的益处，并阻止了关于这一控制GVHD策略的有效性的任何结论。在这项建议中，将对来自DLA半相合捐赠者的HSCT临床前模型中的病毒载体转导的T细胞进行研究。移植需要有功能的同种异体反应性T细胞，在这个模型中潜在的致命性移植物抗宿主病是可以预测的。在目标1中，将带有逆转录病毒载体表达HSV/TK基因的受体特异性细胞毒性T淋巴细胞(CTL)基因修饰(GM)加入到T细胞耗竭的骨髓中，以评估同种异体反应功能。由于T细胞在被激活用于逆转录病毒转导时可能失去同种异体反应，慢病毒载体也将在这个模型中进行研究，因为不需要激活，并且CD4和CD8T细胞都被转导。在目标2中，将评估更昔洛韦在诱导GM T细胞凋亡和随后控制GVHD方面的有效性。通过保留供者T细胞的作用，但防止发生严重的GVHD，异基因HSCT的发病率和死亡率将会降低，并有可能将异基因HSCT的“疗效”优势更广泛地扩展到包括非恶性疾病的患者。

DESCRIPTION (provided by applicant): The overall goal of this project is to develop an effective strategy for management of severe graft-versus-host disease (GVHD) yet preserves donor T cell activity. After allogeneic hematopoietic stem cell transplantation (HSCT), donor T cells contribute to the prevention of graft rejection and relapse (GVH effect) as well as immune recovery but cause GVHD. Current strategies for the management of GVHD do not adequately deal with these competing endpoints. It is proposed that alloreactive donor T cells, modified to express the herpes simplex virus/thymidine kinase gene (HSV/TK; suicide gene) can maintain in vivo function (GVH effect) and be induced to "self-destruct" with ganciclovir to prevent the development of severe GVHD. Preclinical studies of HSCT from transgenic mice that express the HSV/TK gene show that GVHD was controlled and graft rejection did not occur after treatment of the recipient with ganciclovir. Since nondividing nonalloreactive T cells were not induced to apoptose, reconstitution of immunity was improved. However studies in transgenic mice have not reflected the clinical experience to date. In clinical trials, human T cells must be transduced with retroviral vectors after ex vivo expansion with a mitogenic CD3 monoclonal antibody. In these trials, there has been a significant loss of alloreactivity which negated any potential benefit and prevented any conclusions regarding the effectiveness of this strategy for controlling GVHD. In this proposal, studies will be conducted on T cells transduced with viral vectors in a preclinical dog model of HSCT from DLA-haploidentical donors. Functioning alloreactive T cells are required for engraftment and potentially fatal GVHD is predictable in this model. In aim 1, recipient-specific cytotoxic T lymphocytes (CTL) genetically-modified (GM) with retroviral vectors to express the HSV/TK gene will be added back to T-depleted marrow to assess alloreactive function. Since T cells may lose alloreactivity when activated for retroviral transduction, lentiviral vectors will also be studied in this model since activation is not required and both CD4 and CD8 T cells are transduced. In aim 2, the effectiveness of ganciclovir on the induction of apoptosis of GM T cells and the subsequent control of GVHD will be assessed. By preserving the effects of the donor T cells but preventing the development of severe GVHD, the morbidity and the mortality of allogeneic HSCT will be decreased and it will be possible to extend the "curative" benefits of allogeneic HSCT more broadly to include patients with nonmalignant diseases.