Francis G E, Fisher D, Delgado C, Malik F, Gardiner A, Neale D
Poly MASC Pharmaceuticals PLC, Hampstead, London, UK.
Int J Hematol. 1998 Jul;68(1):1-18. doi: 10.1016/s0925-5710(98)00039-5.
Polyethylene glycol (PEG) modification, PEGylation, is a well established technique which has the capacity to solve or ameliorate many of the problems of protein and peptide pharmaceuticals. It is one of the most important of the molecule altering structural chemistry (MASC) techniques and in many settings is enabling technology. The use of PEG as a linker molecule is also beginning to make a contribution to the production of exciting new products. We have previously reviewed the marked differences between methods of PEGylation and the surprising and dramatic impact of different coupling techniques (using different activated PEGs) on factors such as retention of bioactivity, stability and immunogenicity of the resulting PEGylated proteins and peptides. Numerous factors play a part in this variation: the presence or absence of linkers between the PEG and the target molecule; the nature and stability of the bond(s) between the PEG, linker and target; the impact of PEG attachment on surface charge; the coupling conditions; and the relative toxicity of the activated polymer and/or coproduct(s). These are not, however, the only sources of qualitative differences in PEGylated products. Our own experience whilst developing a linkerless PEGylation technique (i.e. one attaching only PEG to the target molecule), which we devised to overcome all the major problems of pre-existing PEGylation techniques, was that considerable modification of the prototype method and a process of 'biological optimisation' was required to achieve good results in terms of conservation of bioactivity. Biological optimisation has not, as far as we are aware, been systematically applied by other groups working in PEGylation. It is the term we use to describe an iterative process for examining and refining all the steps in the PEGylation process, including manufacturing the activated polymer, in order to achieve the best possible conservation of bioactivity and other beneficial features of the method. The application of this biologically optimised PEGylation technique, using tresyl monomethoxy PEG (TMPEG), to a variety of target proteins reveals, as outlined in this review, an exceptional ability to conserve biological activity of the target. This, and the benefit of adding nothing other than PEG itself (which has an excellent safety record), to the protein, as well as other manufacturing and practical advantages, makes the method ideal for the modification of cytokines and other therapeutic proteins.
聚乙二醇（PEG）修饰，即聚乙二醇化，是一种成熟的技术，有能力解决或改善蛋白质和肽类药物的许多问题。它是分子改变结构化学（MASC）技术中最重要的技术之一，在许多情况下是使能技术。将PEG用作连接分子也开始为令人兴奋的新产品的生产做出贡献。我们之前已经综述了聚乙二醇化方法之间的显著差异，以及不同偶联技术（使用不同的活化PEG）对所得聚乙二醇化蛋白质和肽的生物活性保留、稳定性和免疫原性等因素产生的惊人且显著的影响。许多因素导致了这种差异：PEG与靶分子之间是否存在连接子；PEG、连接子与靶之间键的性质和稳定性；PEG连接对表面电荷的影响；偶联条件；以及活化聚合物和/或副产物的相对毒性。然而，这些并不是聚乙二醇化产物质量差异的唯一来源。我们在开发一种无连接子聚乙二醇化技术（即仅将PEG连接到靶分子上）时的经验是，我们设计该技术是为了克服现有聚乙二醇化技术的所有主要问题，但需要对原型方法进行相当大的修改以及一个“生物学优化”过程，以便在生物活性保留方面取得良好结果。据我们所知，其他从事聚乙二醇化研究的团队尚未系统地应用生物学优化。这是我们用来描述一个迭代过程的术语，该过程用于检查和完善聚乙二醇化过程中的所有步骤，包括活化聚合物的制备，以实现生物活性的最佳保留以及该方法的其他有益特性。如本综述所述，将这种使用三氟甲磺酸单甲氧基PEG（TMPEG）的生物学优化聚乙二醇化技术应用于多种靶蛋白时，显示出对靶标生物活性的卓越保留能力。这一点，以及除了PEG本身（PEG具有出色的安全记录）之外不向蛋白质添加任何其他物质的益处，以及其他制造和实际优势，使得该方法成为修饰细胞因子和其他治疗性蛋白质的理想选择。
