Gong Qian, Hazen Meredith, Marshall Brett, Crowell Susan R, Ou Qinglin, Wong Athena W, Phung Wilson, Vernes Jean-Michel, Meng Y Gloria, Tejada Max, Andersen Dana, Kelley Robert F
a Department of Immunology , Genentech Inc. , South San Francisco , CA , USA.
b Department of Antibody Engineering , Genentech Inc. , South San Francisco , CA , USA.
MAbs. 2016 Aug-Sep;8(6):1098-106. doi: 10.1080/19420862.2016.1189049. Epub 2016 May 24.
For some antibodies intended for use as human therapeutics, reduced effector function is desired to avoid toxicities that might be associated with depletion of target cells. Since effector function(s), including antibody-dependent cell-mediated cytotoxicity (ADCC), require the Fc portion to be glycosylated, reduced ADCC activity antibodies can be obtained through aglycosylation of the human IgG1 isotype. An alternative is to switch to an IgG4 isotype in which the glycosylated antibody is known to have reduced effector function relative to glycosylated IgG1 antibody. ADCC activity of glycosylated IgG1 antibodies is sensitive to the fucosylation status of the Fc glycan, with both in vitro and in vivo ADCC activity increased upon fucose removal ("afucosylation"). The effect of afucosylation on activity of IgG4 antibodies is less well characterized, but it has been shown to increase the in vitro ADCC activity of an anti-CD20 antibody. Here, we show that both in vitro and in vivo activity of anti-CD20 IgG4 isotype antibodies is increased via afucosylation. Using blends of material made in Chinese hamster ovary (CHO) and Fut8KO-CHO cells, we show that ADCC activity of an IgG4 version of an anti-human CD20 antibody is directly proportional to the fucose content. In mice transgenic for human FcγRIIIa, afucosylation of an IgG4 anti-mouse CD20 antibody increases the B cell depletion activity to a level approaching that of the mIgG2a antibody.
对于一些用作人类治疗药物的抗体，需要降低效应功能以避免可能与靶细胞耗竭相关的毒性。由于包括抗体依赖性细胞介导的细胞毒性（ADCC）在内的效应功能需要Fc部分进行糖基化，因此可以通过对人IgG1同种型进行去糖基化来获得ADCC活性降低的抗体。另一种方法是转换为IgG4同种型，已知糖基化的该抗体相对于糖基化的IgG1抗体具有降低的效应功能。糖基化的IgG1抗体的ADCC活性对Fc聚糖的岩藻糖基化状态敏感，去除岩藻糖（“去岩藻糖基化”）后，体外和体内的ADCC活性均会增加。去岩藻糖基化对IgG4抗体活性的影响尚未得到充分表征，但已证明其可增加抗CD20抗体的体外ADCC活性。在这里，我们表明抗CD20 IgG4同种型抗体的体外和体内活性均可通过去岩藻糖基化而增加。使用中国仓鼠卵巢（CHO）细胞和Fut8KO-CHO细胞制备的材料混合物，我们表明抗人CD20抗体的IgG4版本的ADCC活性与岩藻糖含量成正比。在人FcγRIIIa转基因小鼠中，IgG4抗小鼠CD20抗体的去岩藻糖基化将B细胞耗竭活性提高到接近mIgG2a抗体的水平。
