The number of therapeutic antibodies in research and development as well as their complexity increases from year to year. Novel therapeutic protein formats, such as Fc-fusions, bispecific or multivalent antibodies are currently in pre-clinical and clinical development. Therefore, the need for biodistribution and imaging studies, e.g. with radiolabeled proteins are very high. However, the labeling process or the label itself can have an impact on binding to cellular receptors, e.g. to neonatal Fc receptor (FcRn), which can lead to altered PK properties compared to the unlabeled antibody. FcRn affinity chromatography allows the assessment of IgG samples with respect to their pH-dependent FcRn interaction. We analyzed IgGs with different types of labels, namely direct iodination with 125 I, chelating agents, such as DOTA and DOTAM, and [3 H]propionate. Direct radio-iodination leads to shifts in FcRn column retention time which might indicate a potentially faster clearance. Furthermore, high conjugation ratios of chelator lower the affinity to FcRn successively, and thus may influence the lysosomal degradation of the antibody in endothelial cells. In contrast, IgGs labeled with [3 H]propionate did not show any timeshifts in FcRn affinity chromatography. This article is based on the oral presentation at the IIS 2018 Prague and highlights the importance of an affinity chromatography for characterization of potential changes in affinity to FcRn itself or charge and hydrophobicity.

中文翻译：

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放射性标记的 IgG 抗体 - 各种标记对新生儿 Fc 受体结合的影响

研发中的治疗性抗体的数量及其复杂性逐年增加。新型治疗性蛋白质形式，例如 Fc 融合、双特异性或多价抗体，目前正处于临床前和临床开发阶段。因此，对生物分布和成像研究的需求非常高，例如使用放射性标记的蛋白质。然而，标记过程或标记本身会影响与细胞受体的结合，例如与新生儿 Fc 受体 (FcRn) 的结合，与未标记的抗体相比，这会导致 PK 特性的改变。FcRn 亲和层析允许评估 IgG 样品的 pH 依赖性 FcRn 相互作用。我们分析了具有不同类型标记的 IgG，即用 125 I 直接碘化，螯合剂，如 DOTA 和 DOTAM，[3 H]丙酸盐。直接放射性碘会导致 FcRn 柱保留时间发生变化，这可能表明清除速度可能更快。此外，螯合剂的高缀合率依次降低了对 FcRn 的亲和力，从而可能影响内皮细胞中抗体的溶酶体降解。相比之下，用 [3 H] 丙酸盐标记的 IgG 在 FcRn 亲和层析中没有显示任何时移。本文基于 IIS 2018 布拉格会议上的口头报告，并强调了亲和色谱对于表征对 FcRn 本身或电荷和疏水性的潜在变化的重要性。螯合剂的高偶联率依次降低了对 FcRn 的亲和力，从而可能影响内皮细胞中抗体的溶酶体降解。相比之下，用 [3 H] 丙酸盐标记的 IgG 在 FcRn 亲和层析中没有显示任何时移。本文基于 IIS 2018 布拉格会议上的口头报告，强调了亲和色谱对于表征对 FcRn 本身或电荷和疏水性的潜在变化的重要性。螯合剂的高偶联率依次降低了对 FcRn 的亲和力，从而可能影响内皮细胞中抗体的溶酶体降解。相比之下，用 [3 H] 丙酸盐标记的 IgG 在 FcRn 亲和层析中没有显示任何时移。本文基于 IIS 2018 布拉格会议上的口头报告，强调了亲和色谱对于表征对 FcRn 本身或电荷和疏水性的潜在变化的重要性。