MONOCLONAL ANTIBODY-TOXIN CONJUGATES FOR TUMOR THERAPY IN VIVO

单克隆抗体选择性结合肿瘤细胞分化 抗原在体外和体内。 自然效应器机制通常不 介导单克隆抗体结合细胞的杀伤，因此我们设计了 将剧毒蛋白质与抗体连接的方法， 选择性地杀死肿瘤细胞。 有两种方法可以将有毒蛋白质（如蓖麻毒素）与抗体偶联， 用于体外杀死抗原阳性细胞。 蓖麻毒素有两个 亚基：A亚基在胞质溶胶中时阻断蛋白质合成， B亚基结合所有细胞表面上的半乳糖基团， 促进蓖麻毒素A链向胞质溶胶的运输。1)联动 蓖麻毒素A链与抗体结合产生具有低非靶向 毒性但靶细胞毒性对于体内应用太慢; 2） 完整蓖麻毒素与抗体的连接导致非常有效的靶细胞 但非靶细胞杀伤必须由配体阻止 其阻断蓖麻毒素B链与细胞的结合。 这限制了其 应用于100 mM乳糖可阻断蓖麻毒素的体外情况 约束力 我们已经成功地开发了几种新的方法来应用 体内免疫毒素。1)克隆毒素，然后改变其结构 在基因水平降低非靶细胞毒性; 2）鞘内 施用免疫毒素治疗脑肿瘤， 动物模型中肿瘤细胞的对数; 3）制备基因表达载体， 用于人脑肿瘤临床试验的工程免疫毒素 患者; 4）预防针对免疫毒素的免疫应答， S）HIV感染细胞免疫毒素的构建; 6)大鼠、豚鼠和恒河猴浦肯野细胞特异性缺失 7）使用人细胞毒性蛋白质如连接至人细胞毒性蛋白质的RNase， 抗体将选择性地靶向细胞。

Monoclonal antibodies selectively bind tumor cell differentiating antigens in vitro and in vivo. Natural effector mechanisms often do not mediate killing of monoclonal antibody bound cells so we have devised methods of linking extremely toxic proteins to the antibodies to selectively kill tumor cells. Two methods of coupling toxic proteins, like ricin to antibodies, have been used to kill antigen-positive cells in vitro. Ricin has two subunits: the A subunit blocks protein synthesis when in the cytosol and the B subunit binds galactose groups on all cell surfaces but also facilitates the transport of ricin A chain to the cytosol. 1) Linkage of the ricin A chain to antibodies yields reagents with low nontarget toxicity but target cell toxicity too slow for in vivo applications; 2) Linkage of intact ricin to antibodies results in very potent target cell toxicity but the nontarget cell killing must be prevented by a ligand which blocks ricin B chain binding to cells. This has limited its application to in vitro situations where 100 mM lactose can block ricin binding. We have succeeded in developing several new approaches to apply immunotoxins in vivo. 1) Cloning of toxins, then altering their structure at the gene level to decrease non-target cell toxicity; 2) intrathecal administration of immunotoxins for therapy of brain tumors that kill 2-5 logs of tumor cells in animal models; 3) preparation of genetically engineered immunotoxins for clinical trials of human brain tumor patients; 4) prevention of immune response against immunotoxin with anti-CD4 antibodies; S) construction of HIV-infected cell immunotoxins; 6) specific deletion of Purkinje cells in rats, guinea pigs and rhesus monkeys; and 7) Use of human cytotoxic proteins such as RNase linked to antibodies will selectively target cells.