Targeting T-cell costimulation and cytokine activation to prevent GVHD and preserve GVL

摘要 移植物抗宿主病（GVHD）是异基因造血干细胞移植后非复发性死亡的主要原因。 细胞移植（alloHCT）。目前的GVHD预防依赖于广泛的抑制性他克莫司为基础的 不能耐受供体T细胞的组合。他克莫司抑制T细胞受体（TCR）活化并损害 调节性T细胞（Treg）寿命和功能。这种新方法不是靶向TCR，而是在 该应用是同时阻断T细胞共刺激和细胞因子活化作为一种策略， 移植物抗白血病（GVL）。T细胞的CD 28共刺激需要 通过mTOR和Aurora激酶的信号转导，其中抑制任一分子可改善GVHD， 啮齿动物IL-6受体指导JAK 2磷酸化STAT 3，STAT 3使致病性Th 1和Th 17极化 开发有益的生物。我们观察到STAT 3活性在异基因HCT受者中增加， 后来发展为急性GVHD。阻断JAK 2或STAT 3也可减少鼠GVHD。我们的数据支持这一 CD 28和IL-6活性的双重抑制是协同的，并提供持久的GVHD预防， 完整GVL。本申请的目的1将在原理验证临床试验中通过以下方式检验该假设： pacritinib与基于西罗莫司的免疫抑制，分别靶向JAK 2和mTOR信号传导， 减少GVHD。目的2和3将检验下游信号分子的中和 由CD 28和IL-6指导的免疫治疗将产生不同的免疫结果，并共同更完全地控制 捐赠的T细胞与JAK 2不同，STAT 3在分子上抵消Treg的发育。我们提供的证据表明， JAK 2阻断允许天然Treg发育，而STAT 3抑制增加诱导型Treg（iTreg）。在 目的2，我们将研究STAT 3/mTOR抑制是否优于JAK 2/mTOR抑制， 通过增强iTreg分化在小鼠中的GVHD。我们提供的证据表明，抑制极光激酶 显著增加iTreg抑制效力。在目标3中，我们将确定是否靶向STAT 3/Aurora 通过增加iTreg分化和功能，比JAK 2/Aurora更好地预防GVHD。这些 这些实验将指导未来无他克莫司的GVHD预防方案的转化和开发。我们 长期目标是开发有效预防GVHD的选择性免疫抑制策略， 维持维持GVL所需的基本T细胞应答。

ABSTRACT Graft-versus-host disease (GVHD) is a leading cause of non-relapse mortality after allogeneic hematopoietic cell transplantation (alloHCT). Current GVHD prophylaxis relies on broadly suppressive tacrolimus-based combinations that fail to tolerize donor T-cells. Tacrolimus inhibits T-cell receptor (TCR) activation and impairs regulatory T-cell (Treg) longevity and function. Rather than targeting the TCR, the novel approach tested in this application is concurrent blockade of T-cell costimulation and cytokine activation as a strategy to spare Tregs, prevent GVHD, and maintain graft-versus-leukemia (GVL). CD28 costimulation of T-cells requires signal transduction by mTOR and Aurora kinase, where inhibiting either molecule ameliorates GVHD in rodents. The IL-6 receptor directs JAK2 to phosphorylate STAT3, which polarizes pathogenic Th1 and Th17 development over beneficial Tregs. We observed that STAT3 activity is increased in alloHCT recipients who later develop acute GVHD. Blockade of JAK2 or STAT3 also reduces murine GVHD. Our data support the concept that dual inhibition of CD28 and IL-6 activity is synergistic and offers durable GVHD prevention with intact GVL. Aim 1 of this application will test this hypothesis in a proof-of-principle clinical trial by combing pacritinib with sirolimus-based immune suppression to respectively target JAK2 and mTOR signaling and reduce GVHD. Aims 2 and 3 will test the hypotheses that neutralization of downstream signaling molecules directed by CD28 and IL-6 will yield distinct immune outcomes and collectively more complete control over donor T-cells. Unlike JAK2, STAT3 molecularly counteracts Treg development. We provide evidence that JAK2 blockade permits natural Treg development, while STAT3 inhibition increases inducible Tregs (iTreg). In Aim 2, we will investigate whether STAT3/mTOR inhibition is better than JAK2/mTOR inhibition in reducing GVHD in mice by enhancing iTreg differentiation. We provide evidence that inhibition of Aurora kinase significantly increases iTreg suppressive potency. In Aim 3, we will determine whether targeting STAT3/Aurora is better than JAK2/Aurora to prevent GVHD by increasing both iTreg differentiation and function. These experiments will direct future translation and development of tacrolimus-free GVHD prophylaxis regimens. Our long-term goal is to develop selective immune suppression strategies that effectively prevent GVHD and maintain essential T-cell responses needed to preserve GVL.