Gilead Sciences has presented promising data from two late-stage trials which demonstrate that the firm’s HIV drug Viread is more effective as a treatment for hepatitis B than its own Hepsera, which is already approved for treating the latter.

Data from two 48-week Phase III trials, Studies 102 and 103, were presented at the annual meeting of the American Association for the Study of Liver Diseases in Boston, Massachusetts. They compared Viread (tenofovir) to Hepsera (adefovir dipivoxil) among patients with HBeAg-negative and HBeAg-positive hepatitis B, respectively.

Specifically in Study 102, 375 patients were randomised in a 2:1 ratio to receive either Viread (300mg) or Hepsera (10mg) and at week 48, 71% of the 250 patients in the Viread arm had a complete response, compared with 49% who were on Hepsera. The 266-patient Study 103 worked on the same ratio and showed that 67% of patients with HBeAg-positive chronic hepatitis B who were taking Viread had a complete response, compared with 12% on the Hespera arm. Both drugs were generally well tolerated in the two trials.

“The efficacy and tolerability results observed among patients in the Viread arm of the study are impressive,” according to Patrick Marcellin, the principal investigator for Study 102. “Hepsera is commonly considered today’s standard of care in chronic hepatitis B therapy and  these data demonstrate that with Viread, it may be possible to achieve an even greater antiviral response.” The data form the basis of Gilead’s filings last month of US and European marketing applications for Viread for the treatment of hepatitis B, and the firm noted that 400 million people worldwide are infected with the virus and it is among the top ten causes of mortality.

<b>Stiff competition from B-MS’ Baraclude</b>
Hepsera sales were $79.3 million for the third quarter of 2007, a 44% increase on the like, year-earlier period, but it is battling for market share with Bristol-Myers Squibb’s Baraclude (entecavir). At the same meeting, the New York-based group announced data from a four-year 146-patient study which showed that 91% (or 98 out of 108) of people treated with Baraclude suppressed the amount of hepatitis B virus in the blood to undetectable levels at week 192. The drug’s third-quarter sales were $72 million, up from $22 million.

Now Gilead is hoping that an approval for Viread in a new indication will help the firm regain top spot in the hepatitis B market and it will be priced, if approved, at $482 for a month's supply, whereas Hepsera costs just over $600.