LC-MS法对抗PD-1信迪利单抗药物分子铰链区序列改构稳定性的研究

LC-MS analysis of sintilimab as an anti-PD-1 therapeutic mab for its improved hinge stability study

抗体药物目前已成为治疗自身免疫性疾病及肿瘤等多种疾病的重要创新药物。以IgG4为框架开发的抗体药物面临的挑战之一是野生型IgG4的铰链区不稳定,容易发生铰链区Fab臂交换现象。将IgG4分子的铰链区序列-CPSC-(野生型IgG4)改构成-CPPC-(改构型IgG4)是降低铰链区交换和提高IgG4类分子稳定性的有效手段。信迪利单抗(sintilimab)是用于肿瘤免疫治疗的全人源抗PD-1抗体,采用IgG4分子框架并对其铰链区序列进行了改构(S228P)。利用LC-MS检测方法从体外(PBS和人血清)到动物体内(SCID小鼠)对改构后的铰链区稳定性进行了评估。结果表明, LC-MS作为一种简便快速的方法可以有效地检测体外和体内IgG4分子的Fab臂交换反应,经IgG4分子改构后的信迪利单抗结构稳定,避免了Fab臂的交换现象。

Monoclonal antibodies(mAbs)have been widely used as therapeutic drugs for treating diseases such as cancers and auto-immune diseases.When using an IgG4 isotype,one of the challenges is the instability of its hinge which is prone to Fab-arm exchange(FAE).The hinge sequence of a wild type IgG4 is-CPSC-,however a single point mutation S228P from-CPSC-to-CPPC-can effectively diminish FAE,thereby improving hinge stability of the IgG4 molecule.Sintilimab is the fully human anti-PD-1 monoclonal antibody designed and developed for immuno-oncology,in which serine 228 in the hinge was engineered to proline to mitigate FAE.In this study,LC-MS is used to study hinge stability of sintilimab in both in vitro(PBS and human serum)and in vivo(SCID mouse)studies.The studies demonstrate that LC-MS is a fast and simple way to monitor for the occurrence of FAE in vitro and in vivo,and FAE can be eliminated by antibody engineering with a single point mutation.