Modulation of T cell Homeostasis in Myelodysplastic Syndrome (MDS)

描述(申请人提供)：骨髓增生异常综合征(MDS)的特征是造血功能不全，导致单系或多系外周血细胞减少，并发展为急性髓系白血病(AML)，约占30%-40%。与其他癌症患者相似，MDS患者存在近端T细胞受体信号通路缺陷，并可能由高龄和癌症相关的免疫抑制微环境引起的T细胞稳态改变。从母体化合物沙利度胺衍生出来的一类新的治疗药物(IMids)具有独特的能力，通过一种涉及CD28受体激活的未知机制来替代不充分的次级抗原非依赖性共刺激信号，从而增强T细胞功能。这些结果提出了一种假设，即来那度胺与细胞疫苗一起逆转T细胞信号缺陷并改善T细胞稳态，将阻止MDS的白血病进展。自从启动这项资助以来，我们已经确凿地证明来那度胺抑制了磷酸酶PP2A。重要的是，我们证明来那度胺与NAVE CD4+T细胞的年龄依赖性增加有关，这与来那度胺治疗后的前T细胞反应有关。考虑到年龄依赖性，这些结果表明来那度胺刺激胸腺释放CD4+NAVE细胞，从而阻断参与胸腺细胞发育的靶点。目的是破译来那度胺在T细胞发育过程中的复杂分子机制，并确认该药物在体内提高了疫苗反应。然而，由于必要的实验必须在体内进行，因此存在明显的局限性。为了解决这个问题，我们现在提出了一个补充实验，使用通过将包括造血干细胞(HSCs)和/或T细胞在内的人类组织植入免疫缺陷小鼠(Prkdcsord IL2r3-/-(NOD/SHI-SCID IL2R-/-或NOG))创建的“人源化”小鼠模型。为了扩大我们对来那度胺和癌症疫苗的研究，我们提出了三个新的补充目标，利用这个小鼠模型，1)确定胸腺功能是否是产生NAOVE和来那度胺诱导的CD4+T细胞功能所必需的，2)确定PP2A是否改变NAOVE T细胞生成的分子检查点，以及3)确定疫苗联合来那度胺是否在高危MDS异种移植模型中调节针对外来和肿瘤相关抗原的抗原特异性T细胞反应。补充目标是高度新颖和创新的，对科学未来的发展具有巨大的影响。由于修订后的申请符合母项目的总体范围(即，在MDS中开发治疗性疫苗)，该项目将为应用于特定人类疾病(即，MDS)的新疗法提供严格的评估，拟议的工作可以在两年内完成，该工作将产生新的资源(即，适用于MDS未来药物发现工作的异种移植模型)，增加兼职工作人员的工作时间，允许雇用新员工，保留现有人员，并聘用具有完成这些新目标所需的重要技能的新的关键人员。 公共卫生相关性：骨髓增生异常综合征(MDS)的特点是有缺陷的血液形成和发展成白血病的高风险，主要发生在65岁以上的人。随着美国人口老龄化，需要为MDS等与年龄相关的疾病制定新的治疗策略。为了使肿瘤疫苗疗法在MDS和癌症患者中产生临床反应，适当的抗原选择、完整的抗原呈递和T细胞功能都是至关重要的。我们提出了一种新的人源化小鼠模型，在该模型中研究来自父母拨款申请的初步数据产生的特定问题，以破译来那度胺和细胞疫苗的联合作用。我们认为，这种新的治疗策略最好在高风险MDS的背景下进行测试，这些MDS通常存活率较低，治疗选择有限，而且可能只对药物有临床反应。机械论研究将有助于我们对T细胞免疫的理解，并提高我们利用这种形式的免疫疗法和其他形式治疗癌症的能力。补充工作符合母项目的总体范围(即在MDS开发治疗性疫苗)，该项目将为应用于特定人类疾病(即MDS)的新疗法提供严格的评估，拟议的工作可以在两年内完成，这项工作将产生新的资源(即适用于MDS未来药物发现工作的异种移植模型)，增加兼职工作人员的工作时间，能够雇用新工作人员，留住现有人员，并与具有完成这些新目标所需重要技能的新的关键人员签订合同。

DESCRIPTION (provided by applicant): Myelodysplastic syndromes (MDS) are characterized by incompetent hematopoiesis that leads to single or multi-lineage peripheral cytopenias with the development of acute myeloid leukemia (AML) in approximately 30-40% of cases. With similarity to other cancer patients, MDS patients have defects in proximal T-cell receptor signaling pathways and altered T-cell homeostasis induced possibly by advanced age and a cancer-associated immunosuppressive microenvironment. A new class of therapeutic drugs (IMiDs), derived from the parent compound thalidomide possess a unique ability to augment T-cell function by substituting for inadequate secondary antigen-independent co-stimulatory signals through an unknown mechanism that involves activation of the CD28 receptor. These results gave rise the hypothesis that reversal of the T-cell signaling defects and improved T-cell homeostasis with lenalidomide along with a cellular vaccine will prevent leukemia progression in MDS. Since initiating the grant, we have conclusively shown that lenalidomide suppresses the phosphatase PP2A. Importantly, we demonstrate that lenalidomide is associated with an age- dependent increase in naove CD4+ T cells that is associated with the pro-T cell response after lenaldiomide treatment. Given the age dependency, these results suggest that lenalidomide stimulates CD4+ naove cell release from the thymus and thus blocks a target that is involved in thymocyte development. The goal is to decipher the complex molecular mechanism of lenalidomide during T cell development and confirm that the drug improves vaccine responses in vivo. However, there are obvious limitations since the necessary experiments must be performed in vivo. To overcome this problem, we now propose supplemental experiments using a "humanized" mouse model created by engraftment of human tissues including hematopoietic stem cells (HSCs) and/or T cells into immunodeficient mice (Prkdcscid IL2r3-/- (NOD/Shi-scid IL2r-/- or NOG). To extend our studies on lenalidomide and cancer vaccines, we propose three new supplemental aims using this mouse model, 1) to determine if thymic function is necessary for naove production and lenalidomide-induced function in CD4+ T cells, 2) to determine if PP2A alters the molecular checkpoint for naove T cell generation and 3) to determine if vaccine administration in combination with lenalidomide modulates antigen-specific T-cell response against foreign and tumor-associated antigens in a xenograft transplantation model of high-risk MDS. The supplemental aims are highly novel and innovative with tremendous implications for the future advancement of science. This application meets the definitions and goals of the NIH recovery act for competitive revisions since the revised application fits the overall scope of the parent project (i.e., development of a therapeutic vaccine in MDS), the project will provide rigorous evaluation for a novel treatment to be applied to a specific human disease (i.e., MDS), the work proposed can be accomplished within a two-year period, the work will generate a novel resource (i.e., xenograft model applicable for future drug discovery efforts in MDS), increases hours for part-time staff, enables the hiring of new staff, retains current personnel, and contracts new key personnel with important skills necessary to complete these new aims. PUBLIC HEALTH RELEVANCE: Myelodysplastic syndromes (MDS) are characterized by defective blood formation and high risk for leukemia development and primarily occur in individuals over the age of 65 years old. New strategies of treatment are needed for age-related diseases such as MDS as the US population ages. For tumor vaccine therapies to produce clinical responses in MDS and in cancer patients, appropriate antigen selection, intact antigen presentation, and T-cell function are all critical. We propose a new humanized mouse model in which to study specific questions generated from preliminary data in the parent grant application to decipher the combined effects of lenalidomide and cellular vaccines. We believe that this new treatment strategy is best tested in the setting of high-risk MDS that generally have poor survival, limited treatment options, and who may have a clinical response to the drug alone. Mechanistic studies will aide our understanding of T-cell immunity and improve our ability to utilize this form of immunotherapy and other forms for the treatment of cancer in general. The supplemental work fits the overall scope of the parent project (i.e., development of a therapeutic vaccine in MDS), the project will provide rigorous evaluation for a novel treatment to be applied to a specific human disease (i.e., MDS), the work proposed can be accomplished within a two-year period, the work will generate a novel resource (i.e., xenograft model applicable for future drug discovery efforts in MDS), increases hours for part-time staff, enables the hiring of new staff, retains current personnel, and contracts new key personnel with important skills necessary to complete these new aims.