ROCK inhibitor suppression of GVHD with retention of GVL response

描述（由申请人提供）：患者造血系统消融后的骨髓移植（BMT）是几种类型白血病的救命治疗。急性移植物抗宿主病（GVHD）是超过三分之一的MHC匹配供体和受体之间骨髓移植（BMT）的严重并发症，也是约15% BMT患者死亡的近因。清除所有供体T细胞的输注骨髓在很大程度上消除了GVHD，但导致更频繁的干细胞移植失败和更高的白血病复发率。GVHD和复发之间的负相关性可归因于移植物抗白血病（GVL）应答，由此供体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，但这一问题目前尚无实际意义，因为有效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尚不可用。GVHD的严重程度取决于同种异体反应的强度、供体T细胞浸润靶器官（皮肤、肠、肝、肺）的能力以及这些组织对免疫介导的损伤的易感性。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进入最易受免疫病理学影响和/或最可能诱导反应性的宿主部位。我们的方法可以通过抑制Rho相关的卷曲螺旋激酶（ROCK 1和2）酶来实现这一点，这些酶在白细胞运动和内皮和上皮紧密连接的松动过程中对细胞骨架功能至关重要。将在MHC和次要组织相容性抗原（miHA）不同的BMT小鼠模型中测试三种小分子ROCK抑制剂。ROCK 1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，SLx 2119是ROCK 2特异性的，并且刚刚通过了作为抗癌药物开发的1期临床试验。我们的初步数据表明，法舒地尔10天（而不是1天）对急性MHC不同GVHD具有高度保护作用，而不会诱导可能损害有益GVL的同种异体耐受。我们建议通过在1周与2周的时间表中在MHC和miHA模型中测试上述三种药物来扩展这一观察结果，以找到最大限度地抑制GVHD的最短治疗持续时间。每种药物的最佳方案将用于在输注的宿主-同源白血病细胞存在下抑制GVHD，并且将在经处理和未经处理的小鼠中监测肿瘤负荷。我们假设ROCK抑制将干扰供体T细胞同种异体激活和/或运输到GVHD的主要位点，并且干扰同种异体激活不会阻碍供体T细胞寻找和攻击更易接近的白血病细胞。我们的目标是确定至少一种ROCK抑制剂的时间表，抑制GVHD，同时保留GVL功能。使用ROCK抑制剂用于GVHD是新颖的，并且成功将加速我们使用ROCK抑制剂与BMT一起治疗白血病和其他肿瘤的长期目标。 公共卫生相关性：骨髓移植（BMT）是治疗某些白血病的有效方法，但由于来自转移的供体白色细胞攻击无防御能力的宿主的免疫应答（称为移植物抗宿主病，GVHD）而变得复杂。这些白色细胞不能仅仅从BMT中去除，因为它们还帮助转移的干细胞产生新的血细胞，并且它们还识别并破坏任何在移植前抗癌治疗中存活的残留白血病细胞（一种称为移植物抗白血病或GVL的现象）。我们建议使用已被证明对其他临床条件安全的药物来抑制关键酶ROCK，以抑制GVHD，同时使GVL反应基本上保持完整。

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. PUBLIC HEALTH RELEVANCE: Bone marrow transplantation (BMT) is an effective treatment for some leukemias, but is complicated by immune responses from the transferred donor white cells attacking the defenseless host (termed graft vs. host disease, GVHD). These white cells cannot just be removed from the BMT because they also help the transferred stem cells generate new blood cells and they also recognize and destroy any residual leukemia cells that have survived pre-transplant anti-cancer therapy (a phenomenon termed graft vs. leukemia, or GVL). We propose to use drugs which have proven safe for other clinical conditions, to inhibit a key enzyme, ROCK, in order to suppress GVHD while leaving GVL responses largely intact.