ALG-170675

ALG-170675 is a potent, orally bioavailable small molecule inhibitor of Programmed Cell Death Ligand 1 (PD-L1), developed by Aligos Therapeutics for the treatment of chronic hepatitis B (CHB). The drug is designed to block the interaction between PD-L1 and its receptor PD-1, a pathway that is often upregulated in chronic viral infections, leading to T-cell exhaustion and impaired immune clearance. By inhibiting this checkpoint, ALG-170675 aims to restore the functionality of HBV-specific T-cells and promote the reduction of viral markers such as hepatitis B surface antigen (HBsAg). In preclinical models, including AAV-HBV mice, ALG-170675 demonstrated significant dose-dependent reductions in HBsAg and HBV DNA. Despite its promising preclinical profile, Aligos has prioritized other candidates in its HBV portfolio, and ALG-170675 has not progressed into clinical trials, with the company later focusing on the PD-L1 candidate ALG-093453 before eventually pausing its PD-L1 program.