IMMUNOTOXINS IN BONE MARROW TRANSPLANTATION

免疫毒素(IT)是一种新型的药理制剂，由以下几种成分组成 与蓖麻毒素等强力催化毒素相关联的单抗 毒素A链(RTA)。虽然已经观察到了IT的疗效，但毒副作用 在已建立的动物模型中，影响限制了疗效 临床试验。理论上，IT应该提供特定的目标小区 由于mAb部分针对特定的表位而被消除 并且是毒素部分内化所必需的，该毒素部分本身 不能有效地内化。因此，令人有些惊讶的是， 这些试剂在体内没有较高的治疗指数。的目标是 这项建议是为了进行全面的、控制良好的研究处理 以了解与IT毒性相关的机制 体内药效受损，然后设计第二代和第三代 它绕过了这些毒性机制。我们选择把这件事作为重点 关于抗Ly1-RTA的建议，因为抗Ly1识别小鼠的同源物 人类CD5。抗人CD5-RTA目前正在进行移植物抗... 宿主病(GVHD)治疗。我们将检验不同的假设 IT分子的不同区域对不同的IT毒性负有责任。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 对IT毒性的抗体激活。因为我们集团的主要利益 是IT在骨髓移植领域的应用，我们 将检验之前未曾探索过的假设，即辐射增强了 体内抗Ly1-RTA毒性。我们将分析以下内容的相对贡献 受者的微环境与淋巴造血系统的比较 通过使用未移植或辐照和同基因移植 LY1等位基因决定因素不同的同源小鼠。一旦我们有了 在IT分子的某些区域和 毒性，我们将调查根据其选择的修改 降低与IT的毒素或抗体活性有关的毒性的能力。 我们将检验这样一种假设，即从RTA中去除糖会降低IT 毒性。我们将检验这一假设，即毒性可以进一步 通过去除单抗的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，我们将进行测试修改 抗Ly1-RTA在我们建立的GVHD模型中的有效性，该模型已被证明 受既往文献中未修饰抗Ly1-RTA毒性的限制 学习。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.