VRUS Reports Phase-2b SVR Data for PSI-7977 in Genotype-2/3 Patients
[These data come from an open-label arm of the PROTON trial, where all of the other arms are for genotype-1 patients (#msg-61668472). After 12 weeks of treatment with PSI-7977 + SoC, the SVR rate for the easier-to-treat genotype-2/3 patients was 96% (24/25) on an ITT basis and 100% (24/24) among completers.
SVR*12* data for the genotype-2/3 patients in this trial were reported at EASL (#msg-61679544), so the only news today is that the SVR12 data held up at 24 weeks post-treatment. (SVR data for the genotype-1 arms will be reported later this year.)]
PRINCETON, N.J., July 20, 2011 /PRNewswire/ -- Pharmasset, Inc. (Nasdaq:VRUS) announced today the final sustained virologic response (SVR) results from its phase 2b PROTON study with PSI-7977 dosed once daily in combination with peginterferon alfa 2a and ribavirin (Peg-IFN/RBV) in subjects with hepatitis C virus (HCV) genotype 2 or 3 who have not been treated previously. Twenty four out of twenty four subjects (100%) who completed treatment achieved an SVR, defined as HCV RNA below the limit of detection (<15 IU/ml) 24 weeks after the completion of treatment. No subject exhibited breakthrough on treatment or relapse after treatment[this is redundant with the prior statement that there was a 100% SVR rate, but what the heck].
Twenty five treatment-naive subjects with HCV genotype 2 or 3 were enrolled in an open label arm of the PROTON trial, receiving PSI-7977 400mg QD with Peg-IFN/RBV for 12 weeks, with no Peg-IFN/RBV follow-up. At the European Association for the Study of the Liver (EASL) in April 2011, Dr J. Lalezari presented interim results from this arm showing that 24 out of 24 subjects achieved an SVR12, defined as HCV RNA below the limit of detection (<15 IU/ml) 12 weeks after the completion of treatment. The combination was generally safe and well tolerated with one subject discontinuing treatment after day 1[hence the 24 rather than 25 in the SVR analysis] and was lost to follow up. Overall PSI-7977 with Peg-IFN/RBV demonstrated potent viral suppression in subjects with HCV genotype 2 or 3 over 12 weeks of treatment.
Pharmasset anticipates reporting the SVR12 results from the PROTON trial in genotype 1 HCV subjects in the second half of 2011.
About the PROTON Trial
The Phase 2b PROTON trial enrolled 121 subjects infected with HCV genotype 1 who have not been treated previously. The primary endpoint of the trial will be the assessment of safety and tolerability of PSI-7977 in combination with Peg-IFN/RBV over 12 weeks with response-guided therapy allowing discontinuation of Peg-IFN/RBV at week 24. The trial was conducted in the U.S. Subjects were randomized (2:2:1) into one of 3 arms:
• PSI-7977 200mg QD in combination with Peg-IFN/RBV for 12 weeks, followed by 12 or 36 weeks of Peg-IFN/RBV; • PSI-7977 400mg QD in combination with Peg-IFN/RBV for 12 weeks, followed by 12 or 36 weeks of Peg-IFN/RBV; • A control arm of matching placebo with Peg-IFN/RBV for 48 weeks.
In addition, 25 treatment-naive subjects with HCV genotype 2 or 3 were enrolled in a fourth, open label arm, receiving PSI-7977 400mg QD with Peg-IFN/RBV for 12 weeks, with no Peg-IFN/RBV follow-up. Subjects were followed for an additional 24 weeks after discontinuation of all therapy to assess SVR.‹
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