GENETICALLY OPTIMIZED IMMUNOTOXINS FOR LEUKEMIA THERAPY

用于白血病治疗的基因优化免疫毒素

• 批准号: 6263185
• 负责人: CHRISTOPHER A PENNELL
• 金额: $ 22.68万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-30 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6263185
• 关键词: CD antigens; SCID mouse; acute lymphocytic leukemia; diphtheria toxin; genetically modified animals; immunoconjugates; neoplasm /cancer immunotherapy; neurotoxins; nonhuman therapy evaluation; pancreatic ribonuclease; pharmacokinetics; recombinant proteins; site directed mutagenesis

DESCRIPTION: (Applicant's Abstract) The applicant's long-term goal is to develop novel, targeted therapeutics for the treatment of human T cell malignancies. Immunotoxins (ITs) are a class of therapeutic agents with a high degree of specificity and a unique mechanism of action. An IT is a hybrid molecule consisting of a targeting moiety linked to a toxin. The targeting moiety selectively binds to a tumor cell and targets it for death via the attached toxin. Generally, ITs are specifically potent against cancer cells in vitro and in animal models of human malignancies. However, ITs are limited clinically by immunogenicity, toxicity, and/or instability. A clinical grade IT called DA7 was synthesized at the University of Minnesota by biochemically linking deglycosylated ricin toxin A chain (dgRTA) to a monoclonal antibody specific for the T cell-associated antigen CD7. A Phase I clinical study of DA7 revealed that its efficacy was primarily limited by instability and nonspecific vascular toxicity. Despite these limitations, DA7 achieved objective clinical responses at the maximal tolerated dose. If the instability and vascular toxicity of DA7 were reduced, then the applicant contends that DA7 could find a therapeutic niche in the treatment of refractory T cell disease, or as an adjuvant to surgery or chemoradiotherapy. The objective of this revised application is to use genetic engineering to enlarge the 'therapeutic window' of DA7 by increasing its stability and decreasing its toxicity. The first specific aim focuses on the construction and testing of recombinant ITs containing a derivative of Diphtheria toxin (DT) linked to CD7-specffic single chain Fv (sFv) fragments. DT will be used initially since it is a component of the only FDA-approved immunotoxin. Modifications of the sFv structure will be made to enhance stability. Novel approaches for the high-level expression of soluble fusion toxins, and for the direct visualization of IT-mediated tumor cell killing in vivo, are included in this aim. The second specific aim focuses on decreasing toxicity (and immunogenicity) by linking the most stable sFv structure identified in Specific Aim l to human RNAses. The RNAses will be engineered to be both resistant to RNAse inhibitors and to be optimally cytotoxic once internalized. All immunotoxins proposed in Specific Aim 1 and Specific Aim 2 will be tested for their stability, relative affinity, pharmacokinetics, toxicity, and anti-tumor activity. These experiments will allow the applicant to determine more precisely the relationships between stability, toxicity, and efficacy. His ultimate goal is to return to the clinic with a more potent version of DA7.

描述：（申请人的摘要）申请人的长期目标是 开发治疗人类 T 细胞的新型靶向疗法 恶性肿瘤。免疫毒素（IT）是一类具有高毒力的治疗剂。 特异性程度和独特的作用机制。 IT 是一个混合体 由与毒素连接的靶向部分组成的分子。目标定位 该部分选择性地与肿瘤细胞结合，并通过 附着毒素。一般来说，IT 对以下部位的癌细胞特别有效： 人类恶性肿瘤的体外和动物模型。但 IT 能力有限 临床上通过免疫原性、毒性和/或不稳定性。临床级 IT 称为 DA7 的药物是在明尼苏达大学通过生物化学方法合成的 将去糖基化蓖麻毒素 A 链 (dgRTA) 连接至单克隆抗体 对 T 细胞相关抗原 CD7 具有特异性。 DA7的I期临床研究 研究表明，其功效主要受到不稳定和非特异性的限制 血管毒性。尽管存在这些限制，DA7 仍实现了客观的临床 最大耐受剂量下的反应。如果不稳定和血管 DA7的毒性降低了，那么申请人认为DA7可以找到一种 难治性 T 细胞疾病的治疗利基，或作为 手术或放化疗的辅助治疗。此次修订的目的 应用是利用基因工程来扩大“治疗窗口” 通过提高 DA7 的稳定性并降低其毒性。第一个 具体目标侧重于重组 IT 的构建和测试 含有与 CD7 特异性单链连接的白喉毒素 (DT) 衍生物 Fv 链 (sFv) 片段。 DT 最初将被使用，因为它是 唯一获得 FDA 批准的免疫毒素。 sFv结构的修改将是 为增强稳定性而制作。高水平表达的新方法 可溶性融合毒素，以及 IT 介导的肿瘤的直接可视化 体内细胞杀伤，都包括在这一目标中。第二个具体目标重点 通过连接最稳定的 sFv 来降低毒性（和免疫原性） 具体目标 l 中对人类 RNA 酶鉴定的结构。 RNA酶将是 设计为既能抵抗 RNAse 抑制剂，又能达到最佳效果 一旦内化就具有细胞毒性。具体目标 1 中提出的所有免疫毒素和 将测试特定目标 2 的稳定性、相对亲和力、 药代动力学、毒性和抗肿瘤活性。这些实验将 使申请人能够更准确地确定之间的关系 稳定性、毒性和功效。他的最终目标是重返诊所 与更强大的 DA7 版本。