Abstract：
The percentage of trisulfide variants is a product quality metric that is monitored during the manufacture of monoclonal antibody (mAb)-based therapeutics. Results from earlier preclinical studies revealed that trisulfide linkages in mAbs are rapidly converted to disulfides in circulation. In this study, casirivimab and imdevimab, which are both IgG1 subclass mAbs that target the non-overlapping epitopes in SARS-CoV2 Spike protein, are used as models to study the kinetics of trisulfide-to-disulfide conversion in vivo in human circulation. To determine the percentage of trisulfide variants in systemic circulation immediately after intravenous injection, both mAbs were immunoprecipitated from serum samples collected from COVID-19 patients that received this cocktail antibody treatment as part of a first-in-human study. The immunoprecipitated mAbs were then digested under non-reducing conditions and evaluated by liquid-chromatography-mass spectrometry (LC-MS). Significant reductions in the percentages of trisulfide variants were observed in serum samples as early as 1 hr after completion of the intravenous infusion. A flow-through dialysis model designed to mimic the redox potential of blood revealed a plausible chemical mechanism for the rapid trisulfide-to-disulfide conversion of IgG1 subclass mAbs under physiological conditions.
摘要：
三硫化物变体的百分比是在基于单克隆抗体(mAb)的治疗剂的制造期间监测的产品质量度量。早期临床前研究的结果表明，mAb中的三硫化物键在循环中迅速转化为二硫化物。在这项研究中,casirivimab和imdevimab,它们都是IgG1亚类单克隆抗体，靶向SARS-CoV2Spike蛋白中的非重叠表位，用作研究人体循环中体内三硫化物到二硫化物转化动力学的模型。为了确定静脉注射后立即在体循环中的三硫化物变体的百分比，两种mAb均从COVID-19患者的血清样本中免疫沉淀,这些患者接受了这种鸡尾酒抗体治疗,作为首次人体研究的一部分.然后将免疫沉淀的mAb在非还原条件下消化并通过液相色谱-质谱(LC-MS)评估。早在静脉内输注完成后1小时,在血清样品中观察到三硫化物变体的百分比显著降低。设计用于模拟血液氧化还原电位的流通透析模型揭示了在生理条件下IgG1亚类mAb的三硫化物到二硫化物的快速转化的合理化学机制。
