GS9857

Appearance

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Mechanism of Action

Voxilaprevir is an orally bioavailable inhibitor of the hepatitis C virus (HCV) non-structural protein 3/non-structural protein 4A (NS3/NS4A) serine protease, with antiviral activity. Upon administration, voxilaprevir binds to the HCV NS3/NS4A serine protease and prevents NS3/NS4A protease-mediated polyprotein maturation. This disrupts both the processing of viral proteins and the formation of the viral replication complex, thereby preventing viral replication and function. NS3, a serine protease, is essential for the proteolytic cleavage of multiple sites within the HCV polyprotein and plays a key role during HCV ribonucleic acid (RNA) replication. NS4A is an activating factor for NS3. HCV is a small, enveloped, single-stranded RNA virus belonging to the Flaviviridae family; HCV infection is associated with the development of hepatocellular carcinoma (HCC).

Uses

Voxilaprevir(GS9857) is a hepatitis C virus (HCV) nonstructural (NS) protein 3/4A protease inhibitor (by Gilead) that is used in combination with sofosbuvir and velpatasvir. The combination has the trade name Vosevi and received a positive opinion from the European Committee for Medicinal Products for Human Use in June 2017. On 18 July 2017, Vosevi was approved by the US Food and Drug Administration.
Voxilaprevir is a new chemical entity recently approved in a fixed-dose combination with sofosbuvir1,2 and velpatasvir.3 Like glecaprevir and grazoprevir, voxilaprevir inhibits the NS3/4A protease involved in viral replication. Sofosbuvir is an NS5B nucleotide polymerase inhibitor and velpatasvir is an NS5A inhibitor.

Application

Voxilaprevir is a Direct-Acting Antiviral (DAA) medication used as part of combination therapy to treat chronic Hepatitis C, an infectious liver disease caused by infection with Hepatitis C Virus (HCV). HCV is a single-stranded RNA virus that is categorized into nine distinct genotypes, with genotype 1 being the most common in the United States, and affecting 72% of all chronic HCV patients. Voxilaprevir exerts its antiviral action by reversibly binding and inhibiting the NS3/4A serine protease of Hepatitis C Virus (HCV). Following viral replication of HCV genetic material and translation into a single polypeptide, Nonstructural Protein 3 (NS3) and its activating cofactor Nonstructural Protein 4A (NS4A) are responsible for cleaving genetic material into the following structural and nonstructural proteins required for assembly into mature virus: NS3, NS4A, NS4B, NS5A, and NS5B. By inhibiting viral protease NS3/4A, voxilaprevir therefore prevents viral replication and function. Treatment options for chronic Hepatitis C have advanced significantly since 2011, with the development of Direct Acting Antivirals (DAAs) such as voxilaprevir. Voxilaprevir has been available since July 2017 in a fixed dose combination product with [sofosbuvir] and [velpatasvir] as the commercially available product Vosevi. Vosevi is approved for the treatment of adult patients with chronic HCV infection with genotype 1, 2, 3, 4, 5, or 6 infection. Notably, Vosevi is approved for use in patients with genotypes 1-6 who have been previously treated with an NS5A inhibitor, or patients with genotypes 1a or 3 infection and have previously been treated with an HCV regimen containing sofosbuvir without an NS5A inhibitor. Prior to Vosevi, there were no approved retreatment options for patients who have previously received, and failed, a regimen containing an NS5A inhibitor for treatment of chronic HCV infection.