Deldeprevir (ACH-2684) is a potent inhibitor of the hepatitis C virus (HCV) NS5A protein, which plays a critical role in viral replication and assembly. It has been investigated for the treatment of chronic hepatitis C infection, particularly in genotype 1 strains. Due to its high potency and specific targeting of NS5A, Deldeprevir has shown strong antiviral activity in clinical trials, often used in combination with other antiviral agents such as NS3/4A protease inhibitors or polymerase inhibitors to enhance efficacy and reduce the risk of resistance. Its development contributed to the advancement of direct-acting antiviral regimens, aiming to improve cure rates and shorten treatment duration for HCV patients. Although further development was discontinued in favor of other candidates, its pharmacological profile helped inform the design of subsequent NS5A inhibitors used in modern HCV therapy.