The binding epitope of sintilimab on PD-1 revealed by AbMap. (26th February 2021)

• Record Type: Journal Article
• Authors: Ma, Mingliang; Qi, Huan; Hu, Chuansheng; Xu, Zhaowei; Wu, Fanlin; Wang, Nan; Lai, Danyun; Li, Yang; Zhang, Hainan; Jiang, Hewei; Meng, Qingfeng; Guo, Shujuan; Kang, Yani; Zhao, Xiaodong; Li, Hua; Tao, Sheng-ce
• Is Part Of: Acta biochimica et biophysica Sinica. Volume 53:Number 5(2021)
• Page Start: 628
• Page End: 635
• Publication Date: 2021-02-26
• Subjects: AbMap -- epitope -- PD-1 -- sintilimab; Biochemistry -- Periodicals; Biophysics -- Periodicals; 572.05
• DOI: 10.1093/abbs/gmab020
• Languages: English
• ISSNs: 1672-9145

Abstract

Abstract: PD-1 plays an important role as an immune checkpoint. Sintilimab is a newly approved PD-1 antibody for cancer immunotherapy with an unknown binding epitope on PD-1. In this study, to elucidate the molecular mechanism by which sintilimab blocks PD-1 activation, we applied Antibody binding epitope Mapping (AbMap) to identify the binding epitope of sintilimab. An epitope was successfully identified, i.e. SLAPKA, aa 127–132. By constructing a series of point mutations, the dominant residues S127, L128, A129, P130, and A132 of PD-1 were further validated by western blot analysis, biolayer interferometry, and flow cytometry. Structural analysis showed that the epitope is partially within the binding interface of PD-1 and PD-L1, and this epitope also partially overlaps with that of nivolumab and pembrolizumab. These results demonstrate that sintilimab can attenuate PD-1 activation by directly competing with the interaction between PD-1 and PD-L1 through binding with the key residues of the FG loop on PD-1. This study also demonstrates the high efficiency and accuracy of AbMap for determining the binding epitope of therapeutic antibodies.