African Americans Have Lower Response Rate To Standard Therapy For Hepatitis C
Hepatitis C (HCV) Infections
African American patients with hepatitis C (HCV) infections experience a lower response rate to the peginterferon alfa-2a and ribavirin combination treatment than Caucasian Americans, according to a study published in the August issue of Gastroenterology, the journal for the members of the American Gastroenterological Association (AGA). Racial differences in viral responses were seen as early as the fourth week of treatment. A pegylated interferon combined with ribavirin is standard therapy for HCV.
Researchers from the Study of Viral Resistance to Antiviral Therapy for Chronic Hepatitis C (Virahep-C), which is funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), conducted the study to determine the potential mechanisms of antiviral resistance among patients who fail to respond to current optimal therapy regimens. While African Americans have a higher prevalence of HCV infection, they have been underrepresented in most therapeutic clinical trials, making it difficult to estimate response rates in these patients.
According to Charles Howell, MD, associate professor of medicine, University of Maryland School of Medicine and chairperson of the Virahep-C Study Group Steering Committee, "The basis for the racial difference in virologic response rates is being addressed by ongoing supplementary studies in genetics, immunology, interferon signaling and pharmacology, and virology. However, our study results indicate that the reduced response rate among African American patients is not caused by the usual predictors such as patient age, gender, pretreatment serum HCV concentrations, amount of fibrosis in the liver biopsy nor amount of medication taken."
Results showed that sustained virologic response (SVR), the primary endpoint, was significantly lower in African Americans compared with Caucasians (28 percent vs. 52 percent; P<.0001). Patients with SVR had not shown evidence of HCV RNA in their blood 24 weeks after the end of treatment. At treatment week 24, 46 percent of African Americans compared with 74 percent of Caucasian patients were HCV RNA negative and were eligible to continue on therapy to 48 weeks. While breakthroughs in virologic response during treatment were more common among African Americans than Caucasian patients (13 percent vs. 6 percent), the relapse rates after treatment were comparable (32 percent vs. 25 percent).
Data indicated that the proportion of the total maximum dose taken of both peginterferon and ribavirin during the first 24 weeks of treatment was significantly less in African Americans versus Caucasian patients; 54 percent of African American patients compared with 73 percent of Caucasian patients took at least 80 percent of the maximum doses of both peginterferon and ribavirin (P<.0001). However, this did not account for the racial difference in SVR rates.
African American and Caucasian patients experienced similar serious adverse events, dose reductions and drug discontinuations. Three deaths were included in the serious adverse events for African American patients