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news.Pharmasset has announced preliminary results of the fourth cohort of a four-week Phase I proof-of-concept clinical trial evaluating R7128 1500mg twice daily in combination with the standard of care, Pegasys plus Copegus, in 20 patients chronically infected with hepatitis C virus genotype 2 or 3 who had not achieved a sustained viral response with prior SOC therapy.
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In this study, preliminary results indicated that R7128 demonstrated significant short-term antiviral activity in patients who were previous non-responders or relapsers to treatment and was generally safe and well tolerated.
Of the 25 patients enrolled, 20 patients received R7128 1500mg BID and five received placebo. Patients receiving R7128 1500mg BID with standard of care (SOC) for four weeks achieved a mean 5 log10 hepatitis C virus (HCV) RNA decline and 90% (18 of 20) achieved undetectable (<15IU/ml) HCV RNA levels (RVR). Patients receiving placebo with SOC for four weeks achieved a mean 3.7 log10 HCV RNA decline and 60% (3 of 5) achieved an RVR. These viral load reductions for patients with genotype 2 or 3 are similar to those reported earlier for patients with genotype 1 treated with 1000mg BID and 1500mg BID and are consistent with the in vitro data demonstrating equal potency by R7128 against HCV genotypes 1, 2, 3 and 4. The preliminary safety and tolerability of R7128 1500mg BID with SOC was comparable to placebo with SOC in cohort 4. Michelle Berrey, chief medical officer of Pharmasset, said: "Longer-term studies of R7128 with SOC are needed to provide additional information about its potential to improve sustained viral response rates and possibly shorten the treatment duration for genotype 2 or 3 HCV patients."