Fig. 5

AP203-mediated T cell activation is dependent on the PD-L1 and CD137 cross-linking. A AP203 promoted T cell activation in the presence of PD-L1-expressing HEK293 cells. T cells cocultured with HEK293 cells with/without PD-L1 overexpression were treated with control antibody, AP203 or its parental antibody alone or in combination for 3 days. The secretion of IL-2 and IFN-γ in the culture supernatant was measured by ELISA. B AP203 promoted T cell activation in a dose-dependent manner when T cells were cocultured with PD-L1 expressing HEK293 cells. The secretion of IL-2 and IFN-γ by T cells from three different donors was measured by ELISA. C AP203 promoted T cell activation when cocultured with various cancer cells expressing PD-L1. Upper panel: surface expression of PD-L1 on MDA-MB-231 (breast cancer cells), NCI-H292 (lung mucoepidermoid carcinoma cells), PC-3 (prostate cancer cells), BxPC-3 (prostate cancer cells), and NCI-H1975 (non-small cell lung cancer cells). PD-L1 expression on the cell surface was assessed by flow cytometry. Lower panel: IL-2 and IFN-γ secretion levels were measured in human CD8 + T cells co-cultured PD-L1-expressing cancer cells after treated with isotype control antibody or AP203 or its parental antibody alone or in combination