Inducible Regulatory T Cells for the Prevention and Treatment of Acute GVHD

描述(申请人提供)：急性移植物抗宿主病(AGVHD)是异基因造血干细胞移植(HSCT)后发病率和死亡率的主要原因。T调节细胞(Tregs)是CD4T细胞的一个亚群，共表达高水平的IL-2ra链(CD25)和转录因子FoxP3。胸腺中产生的自然Tregs(nTregs，CD4 CD25brFoxP3)过继转移已经被证明可以预防小鼠的aGVHD和自身免疫，但需要高比例的nTreg：供体T细胞。外周血来源的nTregs频率低、增殖潜能低，阻碍了nTregs的临床应用。在外周，一群非Treg的CD4T细胞可以被诱导获得Treg表型和功能--这些细胞被称为诱导性Tregs(ITregs)。我们的研究小组首次证明，在IL-2、雷帕霉素和TGFss存在的情况下，人的iTregs可以可靠地激活，从而在异种GVHD小鼠模型中产生稳定的Foxp3表达和有效抑制aGVHD的群体。此外，我们最近开发了一种使用GMP试剂进行细胞纯化、激活和扩增的制造工艺。重要的是，我们已经完成了放大研究，并证明了我们可以在开始培养的两周内从PB Buffy涂层中重复培养&gt；109 iTregs，并从完全分离的PB产品中培养~240x109细胞。有了这些扩增率，我们预计iTreg：捐赠者T细胞的比例将达到5：1，显著超过预防aGVHD的目标最低比例1：1，如临床前小鼠模型所示。然而，对于活动期疾病的患者，可能需要更高的比例或多次使用iTreg。我们的最终目标是生产一种临床级别的现成第三方iTreg产品，用于aGVHD的预防和治疗，我们将 开展一系列“人类首例”临床试验，系统地评估iTregs的安全性和潜在疗效。在这里，我们将建立人类白细胞抗原相合、部分相合和不相合的iTregs预防aGVHD的安全性和动力学。我们将进行一系列具有延伸期的I期试验，以确定新鲜和随后冷冻保存的iTregs的MTD、安全性和潜在疗效。我们将首先确定新鲜的人类白细胞抗原相合的iTregs在人类白细胞抗原相合的同胞供者造血干细胞移植受者中的安全性，然后使用新鲜的(和后来冷冻保存的)来自半倍相合亲属的人类白细胞抗原不相合的iTregs用于人类白细胞抗原相合的非亲缘供者造血干细胞移植的受者的后续研究。前两项临床试验的成功完成以及随后对冷冻保存的iTregs的测试，将证明倒数第二项试验测试来自不匹配的HLA捐赠者的现成iTregs是合理的。在进行临床试验的同时，我们将优化iTreg Expanson的培养条件，以允许多剂量输液，并建立“现成”产品。在这些研究完成后，我们将开发出一套iTregs库，立即用于预防和治疗aGVHD。 公共卫生相关性：骨髓移植后威胁生命的主要并发症之一是急性移植物抗宿主病(GVHD)，由被称为“淋巴细胞”的供者白细胞攻击患者身体而引起。诱导性Tregs(ITregs)是一种白细胞，通常在血液中发现少量，在小鼠身上的研究表明，在移植期间给予iTregs可以预防GVHD。我们计划测试iTregs是否可以预防和治疗人类GVHD。

DESCRIPTION (provided by applicant): Acute graft-versus-host disease (aGVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). T regulatory (Tregs) cells are a subset of CD4+ T cells that co-express high levels of the IL-2Ra chain (CD25) and the transcription factor, FoxP3. Adoptive transfer of natural Tregs (nTregs, CD4+CD25brFoxP3+) that arise in the thymus have already been shown to prevent aGVHD and autoimmunity in mice but high ratios of nTreg:donor T cells are required. Clinical application of nTregs has been hampered by low frequency and low proliferative potential of nTregs derived from peripheral blood (PB). In the periphery, a population of non-Treg CD4+ T-cells can be induced to acquire a Treg phenotype and function - these cells are referred to as inducible Tregs (iTregs). Our group was the first to show that human iTregs could be reliably activated in the presence of IL-2, rapamycin and TGFss, leading to a population with stable Foxp3 expression and potent suppressive of aGVHD in a xenogeneic GVHD murine model. Furthermore, we have recently developed a manufacturing procedure using GMP reagents for cell purification, activation and expansion. Importantly, we have already completed scale-up studies and have demonstrated that we can reproducibly culture >109 iTregs from a PB buffy coat and ~240x109 cells from a full apheresis PB product within 2 weeks of culture initiation. With these expansion rates, we expect to achieve an iTreg:donor T cell ratio up to 5:1, remarkably in excess of the targeted minimum of 1:1 ratio for aGVHD prevention, as shown in preclinical murine models. However, it is possible that higher ratios or multiple doses of iTreg may be required in patients with active disease. With the ultimate goal of manufacturing a clinical grade 'off the shelf' 3rd party iTreg product for aGVHD prophylaxis and treatment, we will embark on a series of 'first-in-human' clinical trials to methodically evaluate the safety and potential efficacy of iTregs. Here, we will establish the safety and kinetics of HLA matched, partially matched, and unmatched iTregs for aGVHD prevention. We will perform a series of phase I trials with an extension phase to determine the MTD, safety profile and potential efficacy of fresh and subsequently cryopreserved iTregs. We will first establish the safety of fresh HLA matched iTregs in recipients of HLA matched sibling donor HSCT, followed by a follow-up study using fresh (and later cryopreserved) HLA mismatched iTregs obtained from a haploidentical relative for use in recipients of HLA-matched, unrelated donor HSCT. The successful completion of these first two clinical trials and the subsequent testing of cryopreserved iTregs, will justify the penultimate trial testing banked 'off-the-shelf' iTregs from an HLA mismatched donor. In parallel to the clinical trials, we will optimize the culture conditions for iTreg expanson required to permit multi-dose infusions and establishment of an "off-the-shelf" product. At the completion of these studies, we will have developed a bank of iTregs for immediate 'off-the-shelf' use for the prevention and treatment of aGVHD. PUBLIC HEALTH RELEVANCE: One of the major life threatening complications after bone marrow transplantation is acute graft-versus-host disease (GVHD) caused by donor white blood cells called "lymphocyte" cells which attacks the patient's body. Inducible Tregs (iTregs) are a type of white blood cells normally found in small amounts in the blood and studies in mice have shown that iTregs given during transplantation can prevent GVHD. We plan to test whether iTregs can prevent and treat GVHD in humans.