MS1-96 is an orally active PD-L1 (programmed death-ligand 1) degrader. It effectively reduces PD-L1 protein expression levels in various colorectal cancer (CRC) cell lines. The compound loses its ability to induce PD-L1 degradation upon HIP1R knockdown. MS1-96 binds directly to PD-L1 (KD= 2.58 μM) and enhances the interaction between HIP1R and PD-L1, altering PD-L1's intracellular transport in clathrin-coated vesicles. Additionally, MS1-96 induces abnormal N-glycosylation of PD-L1, leading to protein instability and accelerated lysosome-mediated degradation. MS1-96 is applicable for colorectal cancer research.

PD-L1:2.58 μM (Kd)

MS1-96 (10 μM, 48 hours) significantly reduces PD-L1 protein levels in RKO cells without affecting PD-L1 mRNA levels. It induces PD-L1 degradation in RKO cells in a time- and dose-dependent manner when administered at concentrations from 0 to 3 μM over 0 to 48 hours. At 1.5 μM for 24 hours, MS1-96 decreases PD-L1 levels on the surface of RKO and LoVo cells， and disrupts PD-1/PD-L1 interactions by downregulating PD-L1 expression in these cells. It enhances T cell-mediated cytotoxicity against RKO cells and reduces the number of surviving cells. Additionally, when RKO cells are co-cultured with activated PBMC, MS1-96 at 1.5 μM for 24 hours increases LDH release, indicating heightened cytotoxicity. Moreover, MS1-96 at 1.5 μM over 0 to 12 hours promotes PD-L1 degradation rather than inhibiting its translation, thus reducing PD-L1 expression levels. This degradation occurs via the lysosomal pathway and is independent of the proteasome or autophagy. Lastly, MS1-96 induces abnormal N-glycosylation of PD-L1 at positions N35, N192, N200, and N219 in RKO cells.

MS1-96, administered orally at doses of 0-400 mg/kg once daily for 10 days, effectively suppresses colorectal cancer tumor growth in MC38 cell xenograft mice by downregulating PD-L1, with a good safety profile. However, when given at the same dosage regimen for 9 days, MS1-96 does not inhibit tumor growth in immunodeficient MC38 cell xenograft mice. At a dose of 200 mg/kg, taken orally once daily for 8 days, MS1-96 demonstrates antitumor activity in MC38 cell xenograft mice, and this activity is strictly dependent on CD8+ T cells.