IMMUNOTOXIN THERAPY OF OLID TUMORS--PRECLINICAL STUDIES

实体瘤的免疫毒素治疗--临床前研究

• 批准号: 6100926
• 负责人: I PASTAN
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6100926
• 关键词: antibody; antineoplastics; breast neoplasms; chemical structure function; clinical research; colon neoplasms; drug design /synthesis /production; drug screening /evaluation; exotoxins; glioma; human tissue; immunoconjugates; immunotoxicity; leukemia; lymphoma; mesothelioma; molecular cloning; neoplasm /cancer immunotherapy; ovary neoplasms; prostate neoplasms

We produce recombinant immunotoxins by fusing the Fv fragments of antibodies to a mutant form of Pseudomoans exotoxin A termed PE38. For immunotoxin therapy or other targeted therapies of cancer to be successful, it is necessary to detect antigenic targets on solid tumors. Our efforts to detect new antigenic targets are summarized as follows: (1) Ovarian cancers and mesotheliomas express a differentiation antigen termed mesothelin. We have used phage display techniques to identify new single chain antibodies to mesothelin. One of these binds with high affinity (Kd approximate 10 nm). An immunotoxin containing this Fv is very cytotoxic to mesothelin containing cells. Further preclinical evaluation is in progress. (2) Glioblastomas: Phage display was used to isolate an Fv (MR1) that binds to a mutant form of the EGF receptor commonly present on glioblastomas and some carcinomas. MR1(Fv)PE38 is only cytotoxic to cells expressing the mutant receptor. Mutagenesis procedures are being used to increase the affinity of MR1. (3) Prostate cancer: We constructed conventional and single chain immunotoxins with MAb E4 which was thought to be prostate specific. The immunotoxins were cytotoxic to prostate cancer cell lines and also to several other epithelial cancers. Unfortunately recent studies show that MAb E4 may react with normal intestine. (4) Intracellular mutant proteins: Many mutant proteins that act as oncogenes are located within the cell. Since mutant peptides derived from these proteins are located on the cell surface it should be possible to produce antibodies that recognize these complexes and use these to target cytotoxic agents to the cell. To determine if such an approach is feasible, we have made a recombinant immunotoxin with a Fab that specifically recognizes a MHC-peptide complex but not the MHC or the peptide alone. This recombinant immunotoxin was only cytotoxic to cells expressing the specific complex. These studies show that cytotoxic agents can be designed that recognize intracellular proteins displayed as MHC- peptide complexes on the cell surface, and also indicate that antibodies which recognize MHC-peptide complexes on cancer cells could be useful for cancer therapy. We are trying to isolate such antibodies. A disulfide stabilized immunotoxin (e23(dsFv)PE38) has been made that binds to the erb B2 oncoprotein present on breast cancers and several other types of cancer. The agent produces complete regressions of xenografts growing in nude mice and is well tolerated by primates. A clinical batch of the immunotoxin has been prepared and an IND will be filed in late 1997. Because immunotoxins are such potent and specific cytotoxic agents, they have other uses besides cancer therapy. We have developed an approach to create new disease models by using an immunotoxin (anti-Tac(Fv)PE38) to treat transgenic mice which express the human IL2 receptor in a tissue specific manner. In a recent experiment, mice with peripheral autonomic neuropathy have been produced.

我们通过融合 抗假单胞菌外毒素A突变体的抗体，称为PE 38。为 免疫毒素疗法或其它癌症靶向疗法， 成功的，有必要检测实体瘤上的抗原靶标。 我们在检测新抗原靶点方面所做的努力总结如下： (1)卵巢癌和间皮瘤表达分化抗原 称为间皮素。我们已经使用噬菌体展示技术来鉴定新的 间皮素单链抗体。其中之一与高 亲和力（Kd约10 nm）。含有该Fv的免疫毒素非常 对含有间皮素的细胞具有细胞毒性。进一步临床前评价 正在进行(2)胶质母细胞瘤：噬菌体展示用于分离胶质母细胞瘤。 Fv（MR 1）与EGF受体的突变形式结合， 存在于胶质母细胞瘤和一些癌中。MR 1（Fv）PE 38仅为 对表达突变体受体的细胞具有细胞毒性。诱变 程序被用来增加MR 1的亲和力。(3)前列 癌症：我们构建了常规和单链免疫毒素， MAb E4被认为是前列腺特异性的。免疫毒素是 对前列腺癌细胞系以及对几种其它细胞系具有细胞毒性 上皮癌不幸的是，最近的研究表明，MAb E4可能 与正常肠道反应。(4)细胞内突变蛋白：许多 作为致癌基因的突变蛋白位于细胞内。以来 源自这些蛋白质的突变肽位于细胞上 表面，应该有可能产生抗体，识别这些 复合物，并使用它们将细胞毒性剂靶向细胞。到 确定这种方法是否可行，我们已经做了一个重组 具有特异性识别MHC-肽的Fab的免疫毒素 复合物，而不是单独的MHC或肽。该重组 免疫毒素仅对表达特异性复合物的细胞具有细胞毒性。 这些研究表明，细胞毒性药物可以被设计成识别 在细胞上以MHC-肽复合物形式展示的细胞内蛋白质 表面，还表明识别MHC-肽抗体 在癌细胞上的复合物可用于癌症治疗。我们 试图分离出这种抗体。 已经制备了二硫键稳定的免疫毒素（e23（dsFv）PE 38）， 与存在于乳腺癌和几种癌细胞上的erb B2癌蛋白结合 其他类型的癌症。该代理生成以下各项的完全回归 异种移植物在裸鼠中生长，并且灵长类动物耐受良好。一 已经制备了免疫毒素的临床批次，并将 1997年底提交的。 由于免疫毒素是如此有效和特异性的细胞毒性剂， 除了治疗癌症还有其他用途我们开发了一种方法 通过使用免疫毒素（anti-Tac（Fv）PE 38）建立新的疾病模型 治疗以免疫抑制剂形式表达人IL 2受体的转基因小鼠， 组织特异性方式。在最近的一项实验中， 产生了自主神经病变。