Figure 1.

Dostarlimab binding to native PD-1 receptor expressed on human and cynomolgus monkey CD3⁺ T cells. Dostarlimab binds with high affinity to native human and cynomolgus monkey PD-1 expressed on the surface of CD3⁺ T cells. Occupancy of dostarlimab on cynomolgus monkey and human CD3⁺ T cells was assessed by preincubating PBMCs from either (a) cynomolgus monkey or (b) human donors with dostarlimab at varying concentrations and then incubating with either a saturating concentration (20 μg/mL) of dostarlimab or IgG4 isotype control before detection with either FITC-anti-CD3 or PE-anti-IgG4 antibodies and analysis by flow cytometry. The number of CD3⁺/IgG4⁺ cells was quantified, and percentage receptor occupancy was calculated as described in Materials and Methods. FITC: fluorescein isothiocyanate; IgG: immunoglobulin G; PBMC: peripheral blood mononuclear cells; PD-1: programmed cell death protein 1; PE: phycoerythrin