Liang J F, Li Y T, Song H, Park Y J, Naik S S, Yang V C
Department of Pharmaceutical Sciences, College of Pharmacy, The University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA.
J Control Release. 2002 Jan 17;78(1-3):67-79. doi: 10.1016/s0168-3659(01)00484-9.
A prodrug delivery system termed "Antibody Targeted, Triggered, Electrically Modified Prodrug-Type Strategy (ATTEMPTS)" has been developed to permit the antibody-directed administration of inactive enzyme drug including tissue-type plasminogen activator (tPA), and allow a subsequent triggered release of the active tPA at the target site. Cation-modified tPA (mtPA) was attached to a heparin-antifibrin complex via ionic interaction, and the active tPA can subsequently be released by the addition of protamine, a competitive heparin inhibitor. Anti-fibrin IgG was conjugated to heparin via an end-point attachment to form the heparin-antifibrin complex which provides the targeting efficiency of the final heparin/mtPA complex. Cation modification was performed by either chemical conjugation by linking (Arg)7Cys to tPA with N-succinimidy-3-(2-pyridyldithio) propionate or by recombinant DNA methods. Results show that the modification process did not significantly alter the specific activity of tPA with regard to plasminogen activation, fibrin-binding ability, and response toward fibrinogen. The complexes of both modified tPA-heparin did not yield any intrinsic catalytic activity owing to the blockage of the active site of tPA by the attached heparin. On the other hand, heparin-induced inhibition of modified tPA activity was reversed by adding protamine, which is similar to that of a prodrug delivery system. These results suggest that heparin/protamine-based enzyme delivery systems may be a useful tool to improve current enzyme therapeutic status, as well as thrombolytic therapy, by both regulating the release of active enzyme and aborting the associated systemic toxic effect. Currently, modification of enzyme drugs has been optimized by recombinant DNA technology assisted by computer simulation. In addition, the original strategy has been revised to obtain enhanced therapeutic efficacy.
一种名为“抗体靶向、触发、电修饰前药型策略（ATTEMPTS）”的前药递送系统已被开发出来，用于实现抗体导向的无活性酶药物（包括组织型纤溶酶原激活剂（tPA））给药，并允许随后在靶位点触发释放活性tPA。阳离子修饰的tPA（mtPA）通过离子相互作用与肝素 - 抗纤维蛋白复合物相连，随后通过添加鱼精蛋白（一种竞争性肝素抑制剂）可释放出活性tPA。抗纤维蛋白IgG通过端点连接与肝素缀合，形成肝素 - 抗纤维蛋白复合物，该复合物提供了最终肝素/mtPA复合物的靶向效率。阳离子修饰可通过化学偶联（将（Arg）7Cys与tPA用N - 琥珀酰亚胺基 - 3 -（2 - 吡啶基二硫代）丙酸连接）或重组DNA方法进行。结果表明，修饰过程在纤溶酶原激活、纤维蛋白结合能力以及对纤维蛋白原的反应方面并未显著改变tPA的比活性。由于附着的肝素阻断了tPA的活性位点，两种修饰的tPA - 肝素复合物均未产生任何内在催化活性。另一方面，添加鱼精蛋白可逆转肝素对修饰tPA活性的抑制作用，这与前药递送系统类似。这些结果表明，基于肝素/鱼精蛋白的酶递送系统可能是一种有用的工具，通过调节活性酶的释放和消除相关的全身毒性作用，来改善当前的酶治疗状况以及溶栓治疗。目前，酶药物的修饰已通过计算机模拟辅助的重组DNA技术进行了优化。此外，原始策略已被修订以获得更高的治疗效果。
