IMMUNOTOXINS AND RECOMBINANT TOXIN THERAPY OF CANCER

新的免疫毒素(ITS)正在开发用于临床。 实验室的工作重点是利用噬菌体展示来识别新的 并针对各种肿瘤产生新的ITS(乳腺， 卵巢、前列腺、肺、结肠、间皮瘤、星形细胞瘤)和淋巴瘤 还有白血病。1.EGF受体的一种突变形式在许多 胶质母细胞瘤、乳腺癌、肺癌和卵巢癌。D.比格纳(杜克 已经制造出了只识别突变受体的单抗。 这些化合物与PE的化学结合物对突变的细胞具有细胞毒作用 受体，但活性较低。高活性重组ITS 不能从这些单抗中产生。采用抗体噬菌体展示技术 产生一种新的抗体，这种抗体能产生非常稳定和活跃的 正在评估临床使用的重组IT。2.前列腺癌 癌症：单抗E4与正常前列腺细胞反应并分化 前列腺癌。它与其他正常组织有反应性。它有 被化学偶联到突变体PE(PE35)上，使其非常 对前列腺癌细胞株的细胞毒作用。这种抗体的基因 正在被克隆以制造一个重组的IT。黑色素瘤：黑色素瘤 黑素细胞含有一种形式的MSH受体(MCS-1)，而不是 存在于其他组织中。我们正在制备针对MCS-1的抗体以 检查它们的可能用处4.卵巢癌：最多 卵巢癌和间皮瘤含有一种名为间皮蛋白的蛋白质。 我们正在开发针对间硫蛋白的高亲和力抗体，这种抗体可以 用来将毒素(或其他细胞毒剂)导向这些细胞。我们 已经克隆了间皮蛋白cdna，并创造了表达大分子 间苯妥英钠的量。这些肿瘤被用来评估靶向 针对间甲硫蛋白的抗体治疗。使用噬菌体展示， 已经发现了针对间皮蛋白的新抗体。5.上皮性 肿瘤：LMB-1产生了几种临床反应，但它会损害 毛细血管，因为它的大尺寸阻碍了它从 发行量。LMB-7比LMB-7小得多，它会损害皮肤上皮细胞 胃，因为它很快就离开了血液循环。我们是 建造几个不同大小的ITS，目标是找到 大小将允许IT从循环中逃逸到 肿瘤，但会限制对胃上皮细胞的访问。我们有 设计了不需要蛋白质分解处理的ITS 在结构域II和III之间或在 REDLK序列之前的结构域III和两个非常活跃的ITS是 用单抗B1和E23的Fv片段(抗erbB2)制成。

New immunotoxins (ITs) are being developed for clinical use. Laboratory efforts are focused on using phage display to identify new antibodies and to produce new ITs directed at various tumors (breast, ovary, prostate, lung, colon, mesothelioma, astrocytoma) and lymphomas and leukemias. 1. A mutant form of the EGF receptor is found in many glioblastomas, breast, lung and ovarian cancers. D. Bigner (Duke University) has made MAbs that recognize only the mutant receptor. Chemical conjugates of these with PE are cytotoxic to cells with mutant receptors but have low activity. Recombinant ITs with high activity could not be produced from these MAbs. Antibody phage display was used to generate a new antibody that produces a very stable and active recombinant IT which is being evaluated for clinical use. 2. Prostate cancer: MAb E4 reacts with normal prostate cells and differentiated prostate cancers. It has reactivity with other normal tissues. It has been chemically coupled to mutant PE (PE35) to make an IT that is very cytotoxic to prostate carcinoma cell lines. The genes of this antibody are being cloned to make a recombinant IT. 3. Melanoma: Melanomas and melanocytes contain a form of the MSH receptor (MCS-1) that is not present in other tissues. We are preparing antibodies to MCS-1 to examine their possible usefulness as ITs 4. Ovarian cancer: Most ovarian cancers and mesotheliomas contain a protein termed mesothelin. We are developing high affinity antibodies to mesothelin which can be used to direct toxins (or other cytotoxic agents) to these cells. We have cloned the mesothelin cDNA and created tumors that express large amounts of mesothelin. These tumors are used to evaluate targeted therapies with antibodies directed at mesothelin. Using phage display, new antibodies to mesothelin have been identified. 5. Epithelial tumors: LMB-1 has produced several clinical responses but it damages capillaries because its large size retards its exit from the circulation. LMB-7 is much smaller and damages epithelial cells of the stomach, because it rapidly leaves the circulation. We are constructing several ITs of different sizes with the goal of finding a size which will allow the IT to escape from the circulation into tumors, but will restrict access to stomach epithelial cells. We have designed ITs that do not require proteolytic processing by inserting a dsFv fragment either between domains II and III or at the end of domain III prior to the REDLK sequence, and two very active ITs were made with Fv fragments of MAbs B1 and e23 (anti-erbB2).