a Analytical and Formulation Development, Agensys, Inc., an affiliate of Astellas, Inc. , Santa Monica , CA.
b Department of Biochemistry and Molecular Biology , University of Miami Miller School of Medicine , Miami , FL.
MAbs. 2018 May/Jun;10(4):583-595. doi: 10.1080/19420862.2018.1440165. Epub 2018 Mar 6.
Cysteine-linked antibody-drug conjugates (ADCs) produced from IgG2 monoclonal antibodies (mAbs) are more heterogeneous than ADCs generated from IgG1 mAbs, as IgG2 ADCs are composed of a wider distribution of molecules, typically containing 0 - 12 drug-linkers per antibody. The three disulfide isoforms (A, A/B, and B) of IgG2 antibodies confer differences in solvent accessibilities of the interchain disulfides and contribute to the structural heterogeneity of cysteine-linked ADCs. ADCs derived from either IgG2-A or IgG2-B mAbs were compared to better understand the role of disulfide isoforms on attachment sites and distribution of conjugated species. Our characterization of these ADCs demonstrated that the disulfide configuration affects the kinetics of disulfide bond reduction, but has minimal effect on the primary sites of reduction. The IgG2-A mAbs yielded ADCs with higher drug-to-antibody ratios (DARs) due to the easier reduction of its interchain disulfides. However, hinge-region cysteines were the primary conjugation sites for both IgG2-A and IgG2-B mAbs.
半胱氨酸连接的抗体药物偶联物（ADC）由 IgG2 单克隆抗体（mAb）产生的比由 IgG1 mAb 产生的 ADC 更具异质性，因为 IgG2 ADC 由更广泛的分子分布组成，通常每抗体含有 0-12 个药物接头。IgG2 抗体的三种二硫键异构体（A、A/B 和 B）赋予了链间二硫键的溶剂可及性差异，并导致半胱氨酸连接的 ADC 的结构异质性。比较了源自 IgG2-A 或 IgG2-B mAb 的 ADC，以更好地了解二硫键异构体对连接部位和缀合物种分布的作用。我们对这些 ADC 的表征表明，二硫键构型会影响二硫键还原的动力学，但对还原的主要部位影响很小。由于其链间二硫键更容易还原，IgG2-A mAb 产生的 ADC 具有更高的药物抗体比（DAR）。然而，铰链区半胱氨酸是 IgG2-A 和 IgG2-B mAb 的主要缀合部位。
