Figure 1.

IBI323 binds to human PD-L1 and LAG-3. (a) Schematic structure of IBI110, Bi127 and IBI323. (b) Binding affinity and kinetics of IBI323 and its parental Fc-fused PD-L1 single-domain antibodies to PD-L1 determined by surface plasma resonance. (c) Binding affinity and kinetics of IBI323 and its parental LAG-3 mAb to LAG-3 determined by surface plasma resonance. (d) Simultaneous binding of IBI323 to human PD-L1 and LAG-3 measured by biolayer interferometry. (e) Binding of IBI323 and its parental antibodies to PD-L1-expressing CHO-S cells. (f) Binding of IBI323 and its parental antibodies to LAG-3-expressing 293-F cells. Cells were incubated with serially diluted IBI323, IBI110, Bi-127 or IgG1 antibody, followed by a PE-conjugated anti-human IgG. MFI was determined by flow cytometry. (g) Flow cytometry analysis of PD-L1 and LAG-3 expression on activated CD4+ T cells. (h) Flow cytometry analysis of PD-L1 and LAG-3 co-expression in activated CD4+ T cells. (i) Primary cell-based binding assay for IBI323, its parental antibodies, and human IgG using activated human CD4+ T cells and anti-human Fc-PE secondary antibody. Data are representative of three independent experiments or three donors