Fig. 3

Structure diagram of the HK010 interaction with PD-L1 and 4-1BB. A The interface between Fab and PD-L1. Heavy chain (cyan), light chain (dark blue), PD-L1 (magenta). B Superposition comparison of the structures of the Fab/PD-L1 and PD-1/PD-L1 complexes in one asymmetric unit (PDB: 4ZQK). Only amino acids on PD-L1 and Fab with hydrogen bond interactions are displayed. Fab (heavy chain: yellow; light chain: pink), PD-1 (bright green), PD-L1 (combined with PD-1 status: silver, binding Fab status: dark green), and the overlapping amino acids on PD-L1 binding with Fab and PD-1 are shown in the ribbon. C The interface of the Fab/4-1BB complex. The 4-1BB CRDs ranging from one to four are highlighted in red, blue, yellow, and magenta, respectively. The heavy chain and light chain of anti-4-1BB Fab are shown in magenta and cyan, respectively. The interface between anti-4-1BB and 4-1BB highlighted the interactions of hydrogen bonds (dashed line) and hydrophobic interactions (lower right). D The affinity assay for the amino acid mutations of 4-1BB and PD-L1 in HK010. E ELISAs for HK010 blocking the binding of PD-L1 to PD-1 and 4-1BB ligand to 4-1BB. F The working model of the HK010 interaction with PD-L1 and 4-1BB. The values are presented as the mean ± SD from one representative of three independent experiments