A sustained response to successful treatment with interferon for hepatitis C virus (HCV) infection can persist for up to 12 years, according to a report in the November issue of the Journal of Medical Virology.

Previous studies have shown remission for up to 5 years after successful treatment with interferon, the authors explain, but HCV eradication from the liver has not been well validated in longer follow-up.

Dr. Natsuko Tsuda from Osaka National Hospital, Osaka, Japan and colleagues monitored 38 patients who had a virological response to interferon therapy, defined as clearance of HCV from the blood after 6 months.

Thirty-seven patients who had a biochemical response were also monitored. These patients were defined as having normal liver function test results after 6 months of therapy, but detectable levels of virus in the blood.

The subjects were followed for 4.4 years to 12 years after interferon therapy.

All sustained virological responders remained persistently negative for HCV in the blood during the entire follow-up period, the authors report. The biochemical responders continued to have HCV detected in the blood and nearly half (46 percent) experienced flared ups.

Four sustained virological responders (but no biochemical responders) developed liver cancer (between 6 months and 5.5 years after treatment), the report indicates. However, all four patients had advanced liver disease before treatment.

HCV was not detected in biopsy samples from 15 sustained virological responders taken 5.9 to 12.5 years after pretreatment biopsies, the researchers note. However, all but one of the 15 biochemical responders who had repeat biopsies had HCV detected in the liver.

In evaluations of liver tissue samples, all measures improved significantly in the sustained virological responders, whereas only partial improvements were observed the biochemical responders. In both groups, evidence of at least mild inflammation remained in the biopsy tissue samples after treatment.

The results suggest that clearance of HCV by 6 months after interferon therapy indicates a “virological cure,” the authors conclude. “Although further studies with a larger number of patients are necessary, control of biochemical disease activity to near-normal levels may also confer favorable long-term…outcomes,” they add.

SOURCE: Journal of Medical Virology, November 2004.