McDonagh Charlotte F, Kim Kristine M, Turcott Eileen, Brown Lindsay L, Westendorf Lori, Feist Tiffany, Sussman Django, Stone Ivan, Anderson Martha, Miyamoto Jamie, Lyon Robert, Alley Stephen C, Gerber Hans-Peter, Carter Paul J
Seattle Genetics, Inc., 21823 30th Drive Southeast, Bothell, WA 98021, USA.
Mol Cancer Ther. 2008 Sep;7(9):2913-23. doi: 10.1158/1535-7163.MCT-08-0295.
An anti-CD70 antibody conjugated to monomethylauristatin F (MMAF) via a valine-citrulline dipeptide containing linker has been shown previously to have potent antitumor activity in renal cell cancer xenograft studies. Here, we generated a panel of humanized anti-CD70 antibody IgG variants and conjugated them to MMAF to study the effect of isotype (IgG1, IgG2, and IgG4) and Fcgamma receptor binding on antibody-drug conjugate properties. All IgG variants bound CD70+ 786-O cells with an apparent affinity of approximately 1 nmol/L, and drug conjugation did not impair antigen binding. The parent anti-CD70 IgG1 bound to human FcgammaRI and FcgammaRIIIA V158 and mouse FcgammaRIV and this binding was not impaired by drug conjugation. In contrast, binding to these Fcgamma receptors was greatly reduced or abolished in the variant, IgG1v1, containing the previously described mutations, E233P:L234V:L235A. All conjugates had potent cytotoxic activity against six different antigen-positive cancer cell lines in vitro with IC50 values of 30 to 540 pmol/L. The IgGv1 conjugate with MMAF displayed improved antitumor activity compared with other conjugates in 786-O and UMRC3 models of renal cell cancer and in the DBTRG05-MG glioblastoma model. All conjugates were tolerated to > or =40 mg/kg in mice. Thus, the IgG1v1 MMAF conjugate has an increased therapeutic index compared with the parent IgG1 conjugate. The improved antitumor activity of the IgG1v1 auristatin conjugates may relate to increased exposure as suggested by pharmacokinetic analysis. The strategy used here for enhancing the therapeutic index of antibody-drug conjugates is independent of the antigen-binding variable domains and potentially applicable to other antibodies.
先前已证明，一种通过含缬氨酸 - 瓜氨酸二肽的连接子与单甲基澳瑞他汀F（MMAF）偶联的抗CD70抗体，在肾细胞癌异种移植研究中具有强大的抗肿瘤活性。在此，我们制备了一组人源化抗CD70抗体IgG变体，并将它们与MMAF偶联，以研究抗体亚型（IgG1、IgG2和IgG4）以及Fcγ受体结合对抗体 - 药物偶联物性质的影响。所有IgG变体均以约1 nmol/L的表观亲和力结合CD70 + 786 - O细胞，药物偶联并未损害抗原结合。亲本抗CD70 IgG1与人FcγRI和FcγRIIIA V158以及小鼠FcγRIV结合，且这种结合不受药物偶联的影响。相比之下，在含有先前描述的突变E233P:L234V:L235A的变体IgG1v1中，与这些Fcγ受体的结合大大降低或消除。所有偶联物在体外对六种不同的抗原阳性癌细胞系均具有强大的细胞毒活性，IC50值为30至540 pmol/L。与MMAF偶联的IgGv1在肾细胞癌的786 - O和UMRC3模型以及DBTRG05 - MG胶质母细胞瘤模型中，与其他偶联物相比显示出更好的抗肿瘤活性。所有偶联物在小鼠体内的耐受剂量均≥40 mg/kg。因此，与亲本IgG1偶联物相比，IgG1v1 MMAF偶联物具有更高的治疗指数。如药代动力学分析所示，IgG1v1澳瑞他汀偶联物抗肿瘤活性的提高可能与药物暴露增加有关。此处用于提高抗体 - 药物偶联物治疗指数的策略独立于抗原结合可变区，并且可能适用于其他抗体。
