Due to the specific reactivity of these compounds to human PD-L1 (but not murine PD-L1), a syngeneic tumor model with murine MC-38 colon tumor cells expressing human PD-L1 (MC38-hPD-L1 tumor model) was used. In the MC38-hPD-L1 tumor model, Lead compounds potently reduced tumor growth similarly to an anti-human PD-L1 antibody, which was used as a positive control for the experiments....and potent anti-tumor effects in an animal model.