Researchers conducted two open label trials to compare
the efficacy of the new drug with the current treatment regimen of ribavirin
and peginterferon alfa-2a. Patients enrolled in the study were not treated
previously for HCV infection and 20% of them had liver cirrhosis.
The first study involved 327
patients infected with HCV genotype 1, 4, 5, or 6. All patients in this trial
received sofosbuvir, ribavirin, and peginterferon alfa-2a for 12 weeks.
The other study was a randomized
one and involved 499 patients with HCV genotype 2 or 3 infection. Patients
received either 12 weeks of sofosbuvir plus ribavirin or 24 weeks of
peginterferon alfa-2a plus ribavirin.
Serum HCV RNA levels were
measured and IL28B genotyping was done to evaluate the response to HCV therapy. By the end of fourth week, 99% of
patients who received sofosbuvir in both the trials recorded a drastic
reduction in serum HCV RNA levels
In the first single-group study, 89% of patients with HCV
genotype 1 and 96% of patients with HCV genotype 4 had sustained virologic
response i.e. undetectable levels of serum HCV RNA levels 12 weeks after the
In the randomized study, 67% of
patients from each group had sustained virologic response. However, the
response rate among patients with genotype 2 infection
was higher than
among those with genotype 3 infection and taking sofosbuvir-ribavirin
combination of drugs.
Adverse effects like anemia and
other Hematologic disorders were more common among patients on
peginterferon-ribavirin regimen than those on sofosbuvir-ribavirin treatment. Researchers could not detect any
viral resistant mutations in the blood samples of patients who had a relapse.
This necessitates further research to identify the cause of relapse.
Authors thus conclude that the efficacy
of Sofosbuvir is impressive and the drug regimen needs further analysis to
improve the response rates in patients with genotype 3 infection
Sofosbuvir for Previously Untreated Chronic Hepatitis
C Infection; Eric Lawitz et al; NEJM April 2013.