The binding of an anti-PD-1 antibody to FcγRΙ has a profound impact on its biological functions

作者：Tong Zhang, Xiaomin Song, Lanlan Xu, Jie Ma, Yanjuan Zhang, Wenfeng Gong, Yilu Zhang, Xiaosui Zhou, Zuobai Wang, Yali Wang, Yingdi Shi, Huichen Bai, Ning Liu, Xiaolong Yang, Xinxin Cui, Yanping Cao, Qi Liu, Jing Song, Yucheng Li, Zhiyu Tang, Mingming Guo, Lai Wang, Kang Li · 发表于：Cancer Immunology Immunotherapy · 年份：2018 · DOI：10.1007/s00262-018-2160-x · 被引用次数：294 · 研究领域：Monoclonal and Polyclonal Antibodies Research、Cancer Immunotherapy and Biomarkers、Neuroendocrine Tumor Research Advances

Antibodies targeting PD-1 have been demonstrated durable anti-cancer activity in certain cancer types. However, the anti-PD-1 antibodies are less or not efficacious in many situations, which might be attributed to co-expression of multiple inhibitory receptors or presence of immunosuppressive cells in the tumor microenvironment. Most of the anti-PD-1 antibodies used in clinical studies are of IgG4 isotype with the S228P mutation (IgG4 S228P ). The functional impact by the interaction of anti-PD-1 IgG4 S228P antibody with Fc gamma receptors (FcγRs) is poorly understood. To assess the effects, we generated a pair of anti-PD-1 antibodies: BGB-A317/IgG4 S228P and BGB-A317/IgG4-variant (abbreviated as BGB-A317), with the same variable regions but two different IgG4 Fc-hinge sequences. There was no significant difference between these two antibodies in binding to PD-1. However, BGB-A317/IgG4 S228P binds to human FcγRI with high affinity and mediates crosslinking between PD-1 and FcγRI. In contrast, BGB-A317 does neither. Further cell-based assays showed that such crosslinking could reverse the function of an anti-PD-1 antibody from blocking to activating. More importantly, the crosslinking induces FcγRI + macrophages to phagocytose PD-1 + T cells. In a mouse model transplanted with allogeneic human cancer cells and PBMCs, BGB-A317 showed significant tumor growth inhibition, whereas BGB-A317/IgG4 S228P had no such inhibition. Immunohistochemistry study revealed an inverse correlatio...