IMMUNOTOXINS IN BONE MARROW TRANSPLANTATION

免疫毒素（IT）是一类新的药理学试剂，由以下组成： 单克隆抗体（mAb）连接到强效催化毒素，如蓖麻毒素 毒素A链（RTA）。 虽然已经观察到IT的功效，但毒性副作用 这些作用限制了在已建立的动物模型中的功效， 临床试验 从理论上讲，IT应该提供特定的靶细胞 由于mAb部分针对特定表位， 并且是毒素部分内化所必需的， 不能有效地内化。 因此，有些令人惊讶的是， 这些试剂在体内不具有更高的治疗指数。 的目标 这项建议是进行一项全面的、控制良好的研究， 与IT毒性，以了解与IT毒性相关的机制。 体内疗效受损，然后设计第二代和第三代 它绕过这些毒性机制。 我们选择将重点放在 关于抗Ly 1-RTA的建议，因为抗Ly 1识别 人CD 5。 抗人CD 5-RTA目前正在进行移植物抗人CD 5-RTA的临床试验。 宿主疾病（GVHD）治疗。 我们将测试不同的假设， IT分子的不同区域负责不同的IT毒性。 我们 将重点关注最有问题的IT毒性，包括肝脏， 血管和肾脏毒性，我们将确定 抗体激活对IT毒性的影响。 因为我们集团的主要利益 是信息技术在骨髓移植领域的应用，我们 将测试以前未探索的假设，即辐射增强， 体内抗Ly 1-RTA毒性。 我们将分析相对贡献 与淋巴造血系统相比， 通过使用非移植或辐照和同源移植的 Ly 1等位基因决定簇不同的同种小鼠。 一旦我们 在IT分子的某些区域之间建立了关系， 毒性，我们将研究根据其 降低与IT的毒素或抗体部分相关的毒性的能力。 我们将检验从RTA中去除糖会降低IT的假设 毒性 我们将检验毒性可以进一步 通过去除mAb的Fc区而减少。 如果这些修改 可以在不牺牲IT活性的情况下降低毒性，我们将测试修改后的 抗Ly 1-RTA在我们建立的GVHD模型中的疗效，该模型已被证明 受过去发表的未修饰的抗Ly 1-RTA的毒性限制 问题研究 这些研究应该为临床提供有价值的见解。 在当前IT使用中观察到的毒性。

Immunotoxins (IT) are a new class of pharmacologic agent consisting of monoclonal antibodies (mAb) linked to potent catalytic toxins such as ricin toxin A chain (RTA). While efficacy of IT has been observed, toxic side effects have limited the efficacy in established animal models and in clinical trials. Theoretically, IT should provide specific target cell elimination since the mAb portion is directed against a specific epitope and is required for the internalization of the toxin moiety which by itself can not efficiently internalize. Therefore, it is somewhat surprising that these reagents do not have a higher therapeutic index in vivo. The goal of this proposal is to perform a comprehensive, well-controlled study dealing with IT toxicity in order to understand the mechanisms involved with the impaired efficacy in vivo, and then, to design second and third generation IT which bypass these toxicity mechanisms. We have chosen to focus this proposal on anti-Ly1-RTA since anti-Ly1 recognizes the murine homologue of human CD5. Anti-human CD5-RTA is now in clinical trials for graft-versus- host-disease (GVHD) treatment. We will test the hypothesis that different regions of the IT molecule are responsible for different IT toxicities. We will focus on the most problematic IT toxicities including hepatic, vascular, and renal toxicities and we will determine the contribution of antibody activation to IT toxicity. Since the major interest of our group is the application of IT to the field of bone marrow transplantation, we will test the previously unexplored hypothesis that irradiation enhances in vivo anti-Ly1-RTA toxicity. We will analyze the relative contribution of the recipient's microenvironment as compared to lymphohematopoietic system by using non-transplanted or irradiated and syngeneically transplanted congeneic mice which differ in Ly1 alleleic determinants. Once we have established a relationship between certain regions of the IT molecule and toxicity, we will investigate modifications chosen on the basis of their ability to reduce toxicity related to the toxin or antibody moeity of IT. We will test the hypothesis that removal of sugars from RTA will reduce IT toxicity. We will test the hypothesis that toxicities can be further reduced by the removal of the Fc region of the mAb. If these modifications can reduce toxicity without sacrificing IT activity, we will test modified anti-Ly1-RTA for efficacy in our established GVHD model which has proven to be limited by the toxicity of unmodified anti-Ly1-RTA in past published studies. These studies should provide valuable insights into the clinical toxicities observed with current IT usage.