Hepatitis C Virus Therapy in the Direct Acting Antiviral Era

Mitchell L. Shiffman

Disclosures

Curr Opin Gastroenterol. 2014;30(3):217-222. 

In This Article

Sofosbuvir

Sofosbuvir is the first polymerase inhibitor to be approved for the treatment of chronic HCV. It is a nucleotide analog, which inhibits the NS5B polymerase and is effective in all HCV genotypes. It is incorporated into the growing RNA sequence during replication and acts as a chain terminator. The appearance of resistance to sofosbuvir is extremely limited and when this does occur the viral species is unable to persist.

Sofosbuvir was studied as triple therapy with PEGINF and RBV for just 12 weeks in patients with genotypes 1, 4, 5 and 6[18**] This was a single arm study with no comparison with PEGINF and RBV because of the marked differences in the duration of treatment. Over 90% of patients treated with sofosbuvir triple therapy were HCV RNA undetectable within 2 weeks and virtually all patients achieved a RVR. The overall SVR rate was 90%: 89% in patients with genotype 1 and 96% in patients with genotype 4. In patients with cirrhosis, the SVR rate was 80%. All seven of the patients with HCV genotypes 5 and 6 achieved SVR. Sofosbuvir triple therapy has not been evaluated in patients who failed either PEGINF and RBV or triple therapy with a protease inhibitor.

The combination of sofosbuvir and RBV represents the first interferon-free regimen approved for use to treat patients with chronic HCV. This combination was initially studied and is approved for use in patients with HCV genotypes 2 and 3.[18**,19**] In patients with HCV genotype 2, sofosbuvir and RBV yielded superior SVR rates compared with PEGINF and RBV. In treatment-naive patients, 12 weeks of sofosbuvir and RBV achieved SVR rates of 91 and 98% in patients with and without cirrhosis respectively. In patients who had previously failed PEGINF and RBV SVR rates of 96 and 60% were observed with 12 weeks of treatment. Extending the duration of treatment from 12 to 16 weeks did increase the SVR in this subgroup of patients to 78%. The recommended duration of sofosbuvir and RBV for patients with HCV genotype 2 is 12 weeks.

In patients with genotype 3, treatment with sofosbuvir and RBV for 12 weeks yielded an SVR rate of only 61% in patients without cirrhosis and 34% in patients with cirrhosis.[18**,19**] These SVR rates are very similar to that observed with PEGINF and RBV. Extending the duration of sofosbuvir and RBV to 16 and 24 weeks increased the SVR rate in all patients with genotype 3 to about 62 and 84%, respectively.[19**,20,21] As a result, the recommended duration of sofosbuvir and RBV for patients with genotype 3 is 24 weeks.

Sofosbuvir and RBV were also studied in patients with genotypes 1, 2 and 3 who had co-infection with HIV.[22] The duration of treatment for patients with genotypes 1 and 3 was 24 and 12 weeks for patients with HCV genotype 2. SVR rates of 76, 92 and 88% were observed for patients with genotype 1, 2 and 3, respectively. This study led to the approval of sofosbuvir and RBV for the treatment of HCV in patients co-infected with HIV.

Sofosbuvir and RBV have also been studied without interferon in patients with HCV and liver cancer awaiting liver transplant and in patients with post-liver transplant recurrent HCV.[23,24] The duration of sofosbuvir and RBV in all of these studies was for 24 weeks. SVR rates of about 75% were achieved in each of these populations. These studies led to the recommendation that sofosbuvir and RBV be utilized in patients with HCV genotype 1 who were unable to receive PEGINF. The recommended duration of therapy in these patients was 24 weeks.

Sofosbuvir is a well tolerated antiviral agent with minimal side-effects. In a study in which sofosbuvir and RBV were compared with placebo in patients who could not take PEGINF and RBV, the only side-effects with increased frequency above placebo were anemia and pruritus, both of which were attributed to RBV.[19**]

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