Holtsberg Frederick W, Ensor Charles Mark, Steiner Marion R, Bomalaski John S, Clark Mike A
Department of Biology, T.H. Morgan Building, University of Kentucky, Lexington, KY 40506, USA.
J Control Release. 2002 Apr 23;80(1-3):259-71. doi: 10.1016/s0168-3659(02)00042-1.
Some tumors, such as melanomas and hepatocellular carcinomas, have a unique nutritional requirement for arginine. Thus, enzymatic degradation of extracellular arginine is one possible means for inhibiting these tumors. Arginine deiminase is an arginine degrading enzyme (ADI) that has been studied as an anti-cancer enzyme. However, ADI has a short serum half-life and, as a microbial enzyme, is highly immunogenic. Formulation of other therapeutic proteins with poly(ethylene glycol) (PEG) has overcome these problems. Here, ADI-PEGs were synthesized using PEGs of varying size, structure (linear or branched chain) and linker chemistries. All ADI-PEGs retained approximately 50% of enzyme activity when PEG was covalently attached to approximately 40% of the primary amines irrespective of the PEG molecular weight or attachment chemistry used. However, it was observed that, as the PEG size increases to 20 kDa, there was a corresponding increase in the pharmacokinetic (pK) and pharmacodynamic (pD) properties of the formulation. Variation in PEG linker or structure, or the use of PEGs >20,000 mw, did not affect the pK or pD. As has been shown with other therapeutic proteins, repeated injection of ADI-PEG into experimental animals resulted in significantly lower titers of antibodies against this protein than unmodified ADI. These data suggest that formulation of ADI with PEG of 20,000 mw results is the optimal method for formulating this promising therapeutic agent.
一些肿瘤，如黑色素瘤和肝细胞癌，对精氨酸有独特的营养需求。因此，细胞外精氨酸的酶促降解是抑制这些肿瘤的一种可能方法。精氨酸脱亚氨酶是一种已作为抗癌酶进行研究的精氨酸降解酶（ADI）。然而，ADI的血清半衰期较短，并且作为一种微生物酶，具有高度免疫原性。用聚乙二醇（PEG）对其他治疗性蛋白质进行制剂化已克服了这些问题。在此，使用不同大小、结构（线性或支链）和连接子化学性质的PEG合成了ADI-PEG。当PEG共价连接到约40%的伯胺上时，无论使用的PEG分子量或连接化学性质如何，所有ADI-PEG均保留了约50%的酶活性。然而，观察到，随着PEG大小增加到20 kDa，制剂的药代动力学（pK）和药效动力学（pD）性质相应增加。PEG连接子或结构的变化，或使用分子量>20000的PEG，均不影响pK或pD。正如其他治疗性蛋白质所显示的那样，向实验动物重复注射ADI-PEG导致针对该蛋白质的抗体滴度明显低于未修饰的ADI。这些数据表明，用20000分子量的PEG对ADI进行制剂化是配制这种有前景的治疗剂的最佳方法。
