N-glycosylation modification on PD-1 has a pronounced effect on camrelizumab binding

N-glycosylation modification on PD-1 has a pronounced effect on camrelizumab binding. steric hindrance that perturb the recognition of PD-L1 with PD-1.124,125 Examples of the reported structures are shown in Figure 2. Open in a separate window Figure 2. Presentation of structures of PD-1-PD-L1 complex and PD-1-antibody complexes. The complex names and the PDB code of the complexes are given below each structure. PD-1and PD-L1 are shown in dark blue and light blue, respectively. The Fab CID 797718 or the Fv domains of mAb are shown in yellow and green, respectively. Structure Gpm6a of PD-1CPD-L1 PD-1 has an extracellular domain comprised by nine -strands (A, A, B, C, C, D, E, F, G), folding into a -sandwich Ig topology.4,36,126 It also has eight loops connecting the ?-strands, and a flexible loop at the N-terminus (Figure 3).30,34 PD-1 contains multiple N-glycosylated sites,36 which affect the binding of certain antibodies.40 Similar to PD-1, PD-L1 also has nine -strands CID 797718 (A, B, C, C, C, D, E, F, G) and the loops connecting them to fold into an extracellular Ig V domain.44,46 The structures of PD-1CPD-L1 complexes have been determined using PD-1 and PD-L1 from different species (Table 2).30,32 These structures have revealed that PD-1 and PD-L1 are oriented nearly orthogonal to each other (Figure 3). PD-1 and PD-L1 associate mainly via hydrophobic interactions between residues on the front faces of both proteins (Figure 3).30 The inter-molecular H-bonds and C stacking are other key driving forces that stabilize PD-1CPD-L1 complexes. 30 The mAbs mainly compete within this interface to block the PD-1-PD-L1 interactions. Open in a separate window Figure 3. The structure of PD-1-PD-L1. (a) The structure of PD-1-PD-L1 complex (PDB:4ZQK). The PD-1 and the PD-L1 are shown in dark blue and light blue, respectively. The residues that make inter-molecular contacts are highlighted in blue (PD-1) and light gray (PD-L1) sticks. (b) Details of the interacting residues that stabilizing the complex. Residues forming the inter-molecular CID 797718 hydrogen bonds and the hydrophobic contacts are presented as sticks. The inter-molecular H-bonds are connected by dashed lines. Structure of PD-1Ccamrelizumab-scFv Anti-PD-1 camrelizumab was developed by Jiangsu Hengrui Medicine Co., Ltd. It is approved by the NMPA for the treatment of classic Hodgkins lymphoma, hepatocellular carcinoma, esophageal squamous cell carcinoma, nasopharyngeal carcinoma and non-squamous non-small-cell lung cancer (NSCLC).21C86C88C127 Gao and colleagues determined the structure of the PD-1-camrelizumab-scFv complex (PDB code: 7CU5) using a VL-(glycine)4Cserine-VH construct of camrelizumab.40 All three heavy chain complementarity-determining regions (HCDRs) and two of three light chain (LC) CDRs of camrelizumab form contacts with PD-1 (Figure 4a, b). Three loops of PD-1 constitute several inter-molecular H-bonds that are crucial for the complex stability, such as the H-bonds between the LCDR3 of camrelizumab and the FG loop of PD-1, and between the HCDR2 of camrelizumab and the BC loop of PD-1. The interface between PD-1 and camrelizumab-scFv partially overlaps with that of PD-1 and PD-L1, indicating that camrelizumab prevents the PD-L1-PD-1 interaction. Open in a separate window Figure 4. Illustration of the importance of the glycosylation of PD-1 in binding with camrelizumab and cemiplimab37. (a) The structure of PD-1-camrelizumab-scFv(PDB:7CU5)40. The PD-1 is colored blue. The camrelizumab are shown in green and yellow orange. The three HCDRs are colored in pink, limon and light magenta. The three LCDRs of light chain are shown in aquamarine, deep teal and light blue. (b) The details of the interacting residues stabilizing the PD-1-camrelizumab-scFv complex. Residues forming the inter-molecular H-bonds are linked with dashed lines and labeled. (c, d) SPR assays of the cemiplimab (c) with various PD-1 mutant proteins and the camrelizumab (d) with various PD-1 mutant proteins. Figure 4(c, d) were reprinted from the Frontiers in Immunology.37 PD-1 contains several N-linked glycosylation sites, which can be modified with a glycan containing two NAGs, two MANs and one FUC. N-glycosylation modification on PD-1 has a.