PD-1 inhibitor SCL-1 is a potent small molecule inhibitor of PD-1/PD-L1 binding and exerts potent antitumor effects.
PD1 inhibitor SCL-1 binds near the PD-1/PD-L1 interface and form hydrogen bonds with Ser62, Asn66, and Lys78 of PD-1.
PD1 inhibitor SCL-1 exhibited moderate inhibitory activities against PD-1/PD-L1 binding compared to an anti-PD-1 antibody, SCL-1 exerted markedly weaker cytotoxic effects on target cells.
PD1 inhibitor SCL-1 (50 mg/kg) exerted significant antitumor effects on PD-L1+ SCC-3 tumors, which were dependent on CD8+ T cell infiltration and PD-L1 expression in tumors.
