The Viral Resistance to Antiviral Therapy of Chronic Hepatitis C (VIRAHEP-C) study is a multicenter clinical trial designed to test how African Americans respond to antiviral therapy for hepatitis C (HVC) compared to Caucasian patients. Reports of clinical trials for HVC demonstrate markedly worse response in African-American patients than in Caucasian patients with no clear explanation for the difference in outcome. A total of 400 patients, equally divided between African American and Caucasians, were enrolled at eight clinical centers throughout the United States. All participants were HCV genotype 1. Participants were treated for 48 weeks with pegylated interferon alfa-2a (180 mcg/week) plus ribavirin (1000-1200mg/day). Participants were followed for an additional 48 weeks after cessation of therapy. Sustained virological response rates (undetectable HCV RNA in serum 24 weeks post-treatment) and durable sustained virological response rates (undetectable HCV RNA in serum 48 weeks post-treatment) between the two cohorts were compared to determine differences in treatment response between the two racial groups. Results showed that African Americans with chronic hepatitis C genotype 1 have lower rates of virologic response to pegylated interferon and ribavirin than Caucasian Americans, as hypothesized. Factors contributing to the differences in response between the groups remain unclear.

The VIRAHEP-C study was designed to test the hypothesis that African Americans respond less well to combination pegylated interferon and ribavirin therapy than Caucasian Americans who have chronic HVC genotype 1, as noted in previous clinical trials. The study aimed to establish rates of response to optimal current therapy in the two ethnic groups, establish patterns of viral kinetics in response to antiviral therapy, and investigate the viral and host factors that determined response to therapy.

The primary outcome measure was a sustained viral response that was defined as the absence of detectable HCV RNA in serum 24 weeks after therapy was stopped. Treatment nonresponse was defined as detectable serum HCV RNA at treatment week 24; virologic breakthrough was defined as the lack of detectable HCV RNA at treatment week 24, but reappearance of detectable HCV RNA between weeks 24 and 48 of treatment; and virologic relapse was defined as a lack of detectable HCV RNA in serum at the end of therapy, but reappearance of HCV RNA 24 weeks later. At week 24 and time points thereafter, missing HCV RNA data were considered a nonresponse.

Participants between the ages of 18 and 70 were enrolled who met the following criteria:

• Of African American or Caucasian race
• Born in the United States
• Quantifiable Serum HCV RNA
• Hepatitis C genotype 1
• Liver biopsy consistent with chronic hepatitis C

Exclusion criteria are documented in the study protocol.

The study showed that African Americans with chronic hepatitis C genotype 1 have lower rates of virologic response to pegylated interferon and ribavirin than Caucasian Americans, as hypothesized. The differences in response between the groups were not explained by disease characteristics, baseline viral levels, or amount of medication taken.