一种单克隆抗体的电荷异质体分析

Analysis of charge variants of a monoclonal antibody

目的对抗程序性死亡受体-1(programmed death-1,PD-1)单克隆抗体的电荷异质体进行结构鉴别及生物学功能分析。方法通过检测抗PD-1单克隆抗体经专一性蛋白酶(唾液酸酶及羧肽酶)酶切前后的变化,初步确认电荷异质体的种类。采用阳离子交换色谱对电荷异质体进行分离和收集,经联用液相色谱-质谱(LC-MS)法分析电荷异质体各组分的组成;通过抑制抗原与配体相互作用影响NFAT荧光素酶报告基因表达的方法确定电荷异质体的生物学功能。结果碱性异质体含量较少,主要变化为重链N-末端谷氨酰胺未环化;酸性异质体主要变化为重链N383脱氨化和糖链末端唾液酸化。各异质体的生物学活性为89%~102%。结论抗PD-1单克隆抗体电荷异质体大部分修饰位点均远离互补决定区(complementary determining region,CDR),且在体外生物学活性方面差异较小。

Objective To identify the structure and analyze the function of charge variants of a monoclonal antibody（m Ab）against programmed death-1（PD-1）receptor. Methods The charge heterogeneity change of anti-PD-1 mAb was primarily confirmed through digestion with specific proteases（sialidase and carboxypeptidase）. The charge variants were isolated and collected by cation-exchange chromatography（CEX-HPLC）, analyzed for the composition of various fractions by liquid chromatography-mass spectrometry（LC-MS）, and determined for in vitro biological activity via bioluminescent reporter-based antigen/ligand blockade bioassay. Results Low levels of basic charge variants were observed, which were mainly due to un-cyclization of N-terminal glutamide in heavy chain. Acidic charge variants were mainly induced by N383 deamination and N-glycan sialylation in heavy chain. The biological activities of various fractions were 89% ~ 102%.Conclusion Most modification sites were away from complementary determining region（CDR）, and thus no significant difference was observed in the biological activities of various charge variants of anti-PD-1 mAb.