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| |  Viral Response in Chronic HCV Can Be Predicted Within 2 Days of Peginterferon Therapy ARLINGTON, Va -- March 20, 2009 -- A study suggests that previously noted low rates of successful hepatitis C virus (HCV) therapy in African Americans are in large part due to very early differences in the antiviral activity induced by interferon. The study is published early online and will appear in the April 15 print issue of the Journal of Infectious Diseases. Studies have shown that African Americans have consistently lower rates of sustained virological response (SVR) to interferon (IFN)-based therapy, compared with Caucasian Americans. A recent study of those with chronic genotype 1 HCV infection found that only 28% of African Americans attained SVR, compared with 52% of Caucasian American patients. The present study showed that the variation in therapy responsiveness between African Americans and Caucasian Americans can be partly explained by differences in viral response noted as early as 1 to 2 days after the first dose of peginterferon. Researchers monitored 341 patients with chronic genotype 1 HCV who underwent therapy with peginterferon and ribavirin for at least 24 weeks throughout 8 medical centres in the United States. They focused on response rates to interferon therapy within the first 28 days of therapy, noting viral factors such as HCV RNA levels and host factors such as race, gender, and weight. Results showed that HCV RNA levels decreased in almost all patients and that the degree and pattern of decrease between African Americans and Caucasian Americans were different. These differences were statistically significant by day 2 of treatment, and the early viral kinetic measurement was a reliable predictor of ultimate SVR rates. After 28 days of treatment, 22% of the Caucasian American but only 12% of African Americans, were HCV RNA negative. These findings are particularly important because they point toward the presence of some block or defect in the immediate antiviral response of those who do not respond to therapy. "The underlying cause of virological nonresponse and the reasons why it is more common among African Americans than Caucasian Americans are not clear," the authors wrote. "[But] the current analyses demonstrated that these differences are fundamentally biologic and become apparent within 24 to 48 hours of starting therapy." In an accompanying editorial, Andrew W. Tai, MD, and Raymond T. Chung, MD, Massachusetts General Hospital, Boston, Massachusetts, agree that the findings will prove vital for future research into HCV, remarking. "[This study] demonstrates that the low rates of SVR in African American patients in response to IFN-based therapy appear to result, in large part, from impaired early viral kinetics. Further studies are necessary to uncover the relevant mechanisms that underlie this defect in IFN signalling … with the hope that such mechanisms can be manipulated to restore interferon responsiveness in the otherwise nonresponsive host." SOURCE: Infectious Diseases Society of America
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