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: 6626710
• 负责人: CHRISTOPHER A PENNELL
• 金额: $ 23.09万
• 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 2004-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6626710
• 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 开发针对人类T细胞治疗的新型靶向治疗方法 恶性肿瘤。免疫毒素（ITS）是一类治疗剂 特异性程度和独特的作用机理。一个是混合动力 分子由与毒素相关的靶向部分组成。目标 部分部分与肿瘤细胞结合，并通过 附着的毒素。通常，它在针对癌细胞中的特定有效 体外和人类恶性肿瘤的动物模型。但是，它是有限的 通过免疫原性，毒性和/或不稳定性在临床上。临床等级IT 名为DA7是由生化在明尼苏达大学合成的 将脱糖基化的ricin毒素A链（DGRTA）连接到单克隆抗体 针对与T细胞相关的抗原CD7的特异性。 DA7的I期临床研究 揭示其功效主要受不稳定性和非特异性的限制 血管毒性。尽管有这些局限性，DA7仍达到了客观的临床 最大耐受剂量的反应。如果不稳定性和血管 DA7的毒性降低，然后申请人认为DA7可以找到一个 治疗难治性T细胞疾病的治疗生态位 辅助手术或化学放疗。这项修订的目的 应用是使用基因工程来扩大“治疗窗口” 通过提高其稳定性并降低其毒性来达到DA7。第一个 具体目的侧重于重组的构建和测试 包含与CD7特定单一相关的白喉毒素（DT）的衍生物 链FV（SFV）片段。 DT最初将使用DT，因为它是 唯一由FDA批准的免疫毒素。 SFV结构的修改将是 为了提高稳定性。新颖的方法用于高级表达 可溶性融合毒素，用于直接可视化IT介导的肿瘤 该目标包括体内细胞杀死。第二个特定目标重点 通过连接最稳定的SFV来降低毒性（和免疫原性） 特定目标l对人类RNass的特定目的确定。 RNass将是 设计为对RNase抑制剂具有抗性，并且是最佳的 细胞毒性曾经内化。在特定目标1中提出的所有免疫毒素和 特定目标2将测试其稳定性，相对亲和力， 药代动力学，毒性和抗肿瘤活性。这些实验会 允许申请人更精确地确定 稳定性，毒性和功效。他的最终目标是返回诊所 具有更有效的DA7版本。