PD-1/PD-L1 Blocking Antibody Assay

Example 10

This example provides in vitro IC₅₀ data for the blocking of the interaction between recombinant human PD-1 (PD-1-Fc Chimera; Sino Biologics) and human PD-L1 expressed CHO cells by anti-PD-L1 antibody G12. Here, CHO cells expressing PD-L1 were pre-incubated with G12 prior to the addition of rhPD-1-Fc chimeric protein. After incubation and washing, PD-1 binding to cell surface expressed PD-L1 was detected using an Alexa-Fluor 647 tagged anti-PD-1 antibody by flow cytometry (Intellicyt HTFC; FL-4H). This example shows that anti-PD-L1 monoclonal antibody G12 was able to inhibit efficiently the binding of PD-1 to PD-L1 expressed on the surface of CHO cells.

Results: As shown in FIG. 8 and Table 4, the IC₅₀ for blocking of the PD-1/PD-L1 cellular interaction by G12 is 1.76E-09 M. Data was collected on the Intellicyt HTFC flow cytometer, processed using FlowJo software, and analyzed and plotted in Graph Pad Prizm using non-linear regression fit. Data points are shown as the median fluorescence detected in the FL-4H channel+/−Std Error.