A randomized clinical trial with natural interferon-alpha monotherapy for 24 or 48 weeks on patients with chronic hepatitis C having genotype 1b infection in high viral titers.

Patients with chronic hepatitis C who are infected with hepatitis C virus of genotype 1b and have a high viral load in serum (>1 Mega equivalents/ml) poorly respond to interferon with the standard regimen. Natural interferon-alpha (nIFN-alpha: OPC-18) was given to 106 such patients randomized into two different therapeutic schedules. One group consisting of 53 patients received daily intramuscular injection with 10 mega units (Meq) for 2-4 weeks and then 5 Meq three times per week until 24 weeks and the other group of 53 patients were placed on the same regimen until 48 weeks. At 24 weeks after the completion of therapy, HCV RNA turned negative in 11 (25%) patients with the 48-week therapy, significantly more frequently than in two (5%) patients with the 24-week therapy (P=0.014). There were no differences in the incidence and severity of adverse effects between the patients who received 24- and 48-week nIFN-alpha. Based on these results, nIFN-alpha with a high-dose induction and extended to 48 weeks would be a reasonable therapeutic option for the patients infected with HCV/1b in high viral loads who do not respond to the standard regimen with a 24-week schedule.