DESIGN AND USE OF CD7-SPECIFIC RECOMBINANT IMMUNOTOXINS

这项应用的长期目标是开发新的 治疗用重组免疫毒素在人骨髓中的应用 移植和体内治疗人类白血病和 淋巴瘤。重组免疫毒素构成一类新的 具有选择性细胞毒性的药理制剂。他们是 融合蛋白中的抗原结合(可变区) 抗体与强有力的催化毒素有关。从基因上讲 关于工程化免疫毒素的有效性，有几种假设 重组免疫毒素与化学结合免疫毒素的对比。 针对泛T细胞抗原CD7的重组免疫毒素将 被用作模型免疫毒素可能被证明是有效的 T-ALL的治疗。在第一个具体目标中，可变区 CD7表达的基因将被用作模型系统。CD7是 几乎所有T细胞急性淋巴细胞白血病(T-ALL)的表达 因此，这些免疫毒素可能被证明是有效的治疗 全部都是。在第一个特定目的中，表达的可变区基因 CD7特异性杂交瘤将与蓖麻毒素A链(RTA)相连 基因以不同的方式确定哪种编码最有效 免疫毒素。这些化合物与RTA化学偶联的效力。这个 活体比较将采用SCID小鼠模型进行T-ALL。 内化、药代动力学和生物分布研究将 检测哪些因素影响重组人的体内效果 和化学免疫结合物。在第二个特定目标中重组 含假单胞菌外毒素变异体的CD7特异性免疫毒素 A(PE38KDEL)的构建和检测。这些活动的目的是 实验是确定RTA和PE38KDEL的细胞毒性是否不同 当靶向CD7时。第三个具体目标是解决一个问题 在所有RTA免疫毒素临床试验中遇到的：剂量限制 由内皮细胞损伤引起的毒性。假设是RTA 单独使用可通过受体介导的内吞作用杀死内皮细胞。 将产生RTA的突变体，并对其进行酶活性筛选 不再绑定和杀死内皮细胞的变体。这个 对这些突变体的鉴定应该允许构建更多 治疗上有效的免疫毒素。

The long-term objective of this application is to develop novel recombinant immunotoxins for therapeutic use in human bone marrow transplantation and for the in vivo treatment of human leukemias and lymphomas. Recombinant immunotoxins comprise a new class of pharmacologic agents designed to be selectively cytotoxic. They are fusion proteins in which the antigen-binding (variable) regions of antibodies are linked to potent, catalytic toxins. Genetically engineered immunotoxins have several hypotheses concerning the efficacies of recombinant versus chemically-linked immunotoxins. Recombinant immunotoxins specific for the pan -T cell antigen CD7 will be used as a model immunotoxins may prove to be effective in the treatment of T -ALL. In the first specific aim, the variable region genes expressed by a CD7 will be used as a model system. CD7 is expressed on virtually all T cell acute lymphoblastic leukemias (T-ALL) and so these immunotoxins may prove to be effective in the treatment of T-ALL. In the first specific aim the variable region genes expressed by a CD7-specific hybridoma will be linked to the ricin toxin A chain (RTA) gene in different ways to determine which encodes the most efficacious immunotoxin. The potency of the these chemically conjugated to RTA. The in vivo comparisons will employ SCID mouse models for T-ALL. Internalization, pharmacokinetic, and biodistribution studies will examine what factors influence the in vivo efficacy of the recombinant and chemical immunoconjugates. In the second specific aim recombinant CD7-specific immunotoxins containing a variant of Pseudomonas exotoxin A (PE38KDEL) will be constructed and assayed. The purpose of these experiments is to determine if RTA and PE38KDEL differ in cytotoxicity when targeted to CD7. The third specific aim addresses a problem encountered in all clinical trials of RTA-immunotoxins: dose-limiting toxicity caused by endothelial cell damage. The hypothesis is that RTA alone can kill endothelial cells via receptor-mediated endocytosis. Mutants of RTA will be generated and screened for enzymatically active variants that no longer bind and kill endothelial cells. The identification of these mutants should allow for the construction of more therapeutically effective immunotoxins.