Reduced elimination of IgG antibodies by engineering the variable region
Reduced elimination of IgG antibodies by engineering the variable region
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DOI：
10.1093/protein/gzq009
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发表时间：
2010-05-01
影响因子：
2.4
通讯作者：
Hattori, K.
中科院分区：
文献类型：
--
作者：
Igawa, T.;Tsunoda, H.;Hattori, K.
据报道，增加IgG抗体对FcRn的结合亲和力的Fc工程化减少了IgG抗体的消除。在此，我们提出了一种新的非FcRn依赖性方法来减少IgG抗体的消除。在正常小鼠中对具有相同恒定区但不同可变区序列的各种人源化IgG 4抗体进行的药代动力学研究显示，具有较低等电点（pI）的抗体具有较长的半衰期。这些抗体表现出与FcRn相当的结合亲和力，并且对于具有较低pI的抗体，在β 2-微球蛋白敲除小鼠中也观察到较长的半衰期，表明药代动力学差异是由于非FcRn依赖性机制所致。基于我们的研究结果，我们试图设计人源化抗IL 6受体IgG 1抗体的药代动力学特性。在可变区中选择的取代（在Fc区中没有取代）降低了pI，但没有降低生物活性，并显示食蟹猴中抗体清除率显著降低。这些结果表明，通过工程化可变区来降低pI可以减少IgG抗体的消除，并且可以提供IgG抗体的Fc工程化的替代方案。
Fc engineering to increase the binding affinity of IgG antibodies to FcRn has been reported to reduce the elimination of IgG antibodies. Herein, we present a novel non-FcRn-dependent approach to reduce the elimination of IgG antibodies. Pharmacokinetic studies conducted in normal mice of various humanized IgG4 antibodies, which had identical constant regions but different variable region sequences, revealed that an antibody with a lower isoelectric point (pI) has a longer half-life. These antibodies exhibited comparable binding affinity to FcRn, and with the antibodies with lower pIs, a longer half-life was also observed in beta 2-microglobulin knockout mice, suggesting that differences in the pharmacokinetics were due to a non-FcRn-dependent mechanism. On the basis of our findings, we attempted to engineer the pharmacokinetic properties of a humanized anti-IL6 receptor IgG1 antibody. Selected substitutions in the variable region, without substitution in the Fc region, lowered the pI but did not reduce the biological activity and showed a significant reduction in the clearance of the antibody in cynomolgus monkey. These results suggest that lowering the pI by engineering the variable region could reduce the elimination of IgG antibodies and could provide an alternative to Fc engineering of IgG antibodies.