ROCK inhibitor suppression of GVHD with retention of GVL response

描述(申请人提供)：骨髓移植(BMT)后，患者的造血系统消融是一种挽救生命的治疗多种类型的白血病。急性移植物抗宿主病(GVHD)是MHC相合的供受者间超过三分之一的骨髓移植(BMT)的严重并发症，也是约15%的BMT患者死亡的直接原因。清除所有供体T细胞的骨髓可以在很大程度上消除GVHD，但会导致更频繁的干细胞移植失败，以及更高的白血病复发率。移植物抗白血病(GVL)反应与移植物抗白血病(GVL)反应呈负相关，供者T细胞识别残留白血病细胞上的宿主同种异体抗原。目前尚不清楚是否有足够数量的供体T细胞识别白血病特异性抗原，以在缺乏同种异体反应性的情况下提供保护，但这个问题目前尚无定论，因为目前还没有一种有效地去除所有同种异体反应性细胞同时保留白血病特异性细胞的技术。GVHD的严重程度取决于同种异体反应的强度，供者T细胞对靶器官(皮肤、肠道、肝脏、肺)的渗透能力，以及这些组织对免疫介导的损伤的敏感性。考虑到消除同种异体反应性供体细胞的固有问题，最佳的理论方法可能是限制它们访问最容易受到免疫病理影响的宿主部位，和/或最有可能引发反应性的宿主部位。我们的方法可能是通过抑制Rho相关卷曲线圈激酶(ROCK1&2)酶来实现这一点，该酶在白细胞运动和内皮与上皮紧密连接的松动过程中对细胞骨架功能至关重要。三种小分子岩石抑制剂将在MHC和次要组织相容性抗原(MIHA)不同的BMT小鼠模型中进行测试。ROCK1和2的两种抑制剂(替米沙坦和法舒地尔)作为血管扩张剂具有广泛的临床安全性记录。第三，SLx2119是ROCK2特异性的，刚刚通过了作为抗癌药物开发的第一阶段临床试验。我们的初步数据显示，10天(而不是1天)的法舒地尔对急性MHC不同的GVHD具有高度的保护作用，而不会导致可能损害有益的GVL的同种异体耐受。我们建议通过在MHC和MIHA模型中以1周和2周的时间表测试上述三种药物来扩大这一观察范围，以找到最短的治疗时间，最大限度地抑制GVHD。每种药物的最佳方案将用于在输注宿主同基因白血病细胞的情况下抑制GVHD，并将监测治疗和未治疗小鼠的肿瘤负担。我们假设，ROCK抑制将干扰供者T细胞的同种异体激活和/或运输到GVHD的初级部位，而干扰同种异体激活不会阻碍供体T细胞寻找和攻击更容易获得的白血病细胞。我们的目标是确定至少一种抑制GVHD同时保留GVL功能的ROCK抑制剂的方案。使用ROCK抑制剂治疗GVHD是新颖的，成功将加速我们在骨髓移植中使用ROCK抑制剂治疗白血病和其他肿瘤的长期目标。

DESCRIPTION (provided by applicant): Bone marrow transplantation (BMT) following ablation of the patient's hematapoietic system is a life-saving treatment for several types of leukemia. Acute graft vs. host disease (GVHD) is a serious complication in more than a third of bone marrow transplants (BMTs) between MHC matched donors and recipients, and the proximate cause of death in ~ 15% of BMT patients. Purging infused marrow of all donor T cells largely eliminates GVHD, but results in more frequent stem cell failure to engraft, and higher rates of leukemia relapse. The inverse correlation between GVHD and relapse is attributable to the graft vs. leukemia (GVL) response, whereby donor T cells recognize host alloantigens on residual leukemia cells. It is unclear whether sufficient numbers of donor T cells recognize leukemia specific antigens to afford protection in the absence of alloreactivity, but this issue is presently moot, since a technique for efficiently removing all alloreactive cells while retaining leukemia specific cells is not yet available. The severity of GVHD depends on the strength of the alloreactive response, the ability of donor T cells to infiltrate target organs (skin, gut, liver, lungs), and the susceptibility of those tissues to immune mediated damage. Given the problems inherent in eliminating alloreactive donor cells, the optimal theoretical approach might be to limit their access to host sites most susceptible to immunopathology, and/or most likely to induce reactivity. Our approach may accomplish this by inhibition of Rho associated coiled coil kinases (ROCK1&2) enzymes crucial for cytoskeletal function during leukocyte motility and loosening of endothelial and epithelial tight junctions. Three small molecule ROCK inhibitors will be tested in MHC and minor histocompatibility antigen (miHA) disparate BMT mouse models. Two inhibitors of ROCK1&2 (Telmisartan and Fasudil) have extensive clinical safety records as vasodilators. The third, SLx2119 is ROCK2 specific, and has just passed Phase 1 clinical trials on the path to development as an anti-cancer drug. Our preliminary data indicate that 10 days (but not 1 day) of Fasudil is highly protective against acute MHC disparate GVHD, without inducing allotolerance that could compromise beneficial GVL. We propose to extend this observation by testing the three mentioned drugs in both MHC and miHA models in 1 vs. 2 week schedules, to find the shortest duration of treatment that maximally suppresses GVHD. The optimal schedule for each drug will be used to suppress GVHD in the presence of infused host- syngeneic leukemia cells, and tumor burden will be monitored in treated and untreated mice. We hypothesize that ROCK inhibition will interfere with donor T cell alloactivation and/or trafficking to primary sites of GVHD, and that interference with alloactivation will not hinder donor T cells from finding and attacking more accessible leukemia cells. Our objective is to determine at least one schedule of ROCK inhibitor that suppresses GVHD while sparing GVL function. Using ROCK inhibitors for GVHD is novel, and success would accelerate our long term goal of using ROCK inhibitors with BMT, to treat leukemias and other tumors.