PD-1/PD-L1-IN-32 (compound A56) is a potent inhibitor of PD-1/PD-L1 with an IC50 value of 2.4 nM, demonstrating significant anticancer activity. It effectively suppresses tumor growth in the hPD-L1 MC38 humanized mouse model and exhibits negligible toxicity to the normal functions of the mice [1].

Pharmacokinetic analysis of PD-1/PD-L1-IN-32 (compound A56) was conducted in SD rats [1]. The following parameters were obtained: for intravenous (iv) administration at a dose of 8 mg/kg, the area under the curve (AUC) from time 0 to the last measurable time point (0-t) was 11,487.46 μg/L·h, AUC from time 0 to infinity (0-∞) was 13,353.19 μg/L·h, the maximum plasma concentration (Cmax) was 6,227.50 μg/L, the time to reach Cmax (Tmax) was 0.08 h, the elimination half-life (t1/2) was 0.99 h, the volume of distribution (V1) was 1.09 L/kg, and the clearance (CL) was 0.60 L/h/kg. For oral gavage (ig) at 40 mg/kg, the AUC (0-t) was 63,579.08 μg/L·h, AUC (0-∞) was 65,527.75 μg/L·h, Cmax was 21,504.90 μg/L, Tmax was 1.75 h, t1/2 was 1.72 h, V1 was 1.80 L/kg, CL was 0.62 L/h/kg, and bioavailability (F) was 114.09%. Lastly, for intraperitoneal (ip) administration at 10 mg/kg, the AUC (0-t) was 9,729.84 μg/L·h, AUC (0-∞) was 10,504.11 μg/L·h, Cmax was 4,156.54 μg/L, Tmax was 0.88 h, t1/2 was 2.43 h, V1 was 2.94 L/kg, and CL was 1.21 L/h/kg.