By Liz Highleyman

Prior studies have shown that rapid virological response (RVR) at 4 weeks to combination therapy with pegylated interferon plus ribavirin predicts achievement of sustained virological response (SVR) continued undetectable viral load 24 weeks after completion of treatment in both HCV monoinfected and HIV-HCV coinfected individuals.

At the XVII International AIDS Conference taking place this week in Mexico City, researchers from Argentina reported that HCV viral kinetics even during the first 24 hours of therapy predict sustained response in coinfected patients.

As background, the investigators noted that among HIV negative chronic hepatitis C patients treated with pegylated interferon/ribavirin, a rapid decline in HCV RNA has been reported within the first 24-48 hours; less is known, however, about very early virological response in HIV positive people.

The study team evaluated the association between HCV viral load decay during the first 24 hours of therapy and RVR at week 4 and early virological response (EVR) at week 12. The analysis included 11 HIV-HCV coinfected patients undergoing treatment with pegylated interferon plus weight-based ribavirin. Participants had blood samples taken at baseline, at 24 hours, and at 4 and 12 weeks.

All but one of these patients were on HAART. Overall, they had well-controlled HIV disease, with a median CD4 count of 500 cells/mm3. Most (n=8) had hard-to-treat HCV genotype 1, followed by 1 person with genotype 2, and 2 with genotype 3.

Results

• At 24 hours, the median HCV RNA level had fallen to about 85,000 IU/mL from a baseline level of about 661,000 IU/mL.

• 3 out of 11 patients achieved RVR at week 4.

• 8 out of 11 achieved EVR at week 12.

• HCV viral load decayed by a mean 98.7% among patients who achieved RVR and by 85.4% among those who achieved EVR.

• In contrast, patients who did not achieve virological response at these early time points had only a mean 51.3% reduction in HCV RNA during first 24 hours.

Based in these findings, the investigators concluded that a significant decline in HCV viral load (greater than 85%) at 24 hours in HIV-HCV coinfected patients treated with pegylated interferon plus ribavirin is associated with the achievement of RVR or EVR.

They added, "This very early time point assessment of viral decline could be of clinical relevance in those patients with severe toxicity during treatment," as a way to evaluate the risks and benefits of continuing therapy, as well as in resource-limited settings where treatment availability is limited and a cost/benefit approach is warranted.

Hospital Juan A Fernández, Infectious Diseases Unit, Buenos Aires, Argentina; National Reference Center for AIDS, School of Medicine, Buenos Aires University, Buenos Aires, Argentina.

8/08/08

Reference
N Laufer, F Bolcic, E Socias, and others. HCV kinetic during the first 24 hours of treatment and its relationship with RVR/EVR in HCV/HIV coinfected patients. XVII International AIDS Conference (AIDS 2008). Mexico City. August 3-8, 2008. Abstract WEPDB204. (Abstract)