As a leading hepatologist has revealed more good news for Gilead's HIV-turned-hepatitis B treatment Viread (tenofovir), the drug received European approval for treating the liver disease

Two days before the approval was granted, the Annual Meeting of the European Association for the Study of the Liver in Milan heard evidence from two studies that Viread had kept up its impressive performance in the treatment of chronic HBV infection, following 48-week trial data released last year. Hepatologist Professor Patrick Marcellin of the Hôpital Beaujon and University of Paris, said: "These are more good results. This latest 72-week data shows that the drug's effect is maintained at the level it was at 48 weeks."

He said the latest results showed that Viread was still stopping viral replication in up to 90% of patients, with little or no evidence of drug resistance. The ongoing studies 102 and 103 are designed to test Viread in patients with HBeAg-negative and HBeAg-positive forms of chronic hepatitis B, respectively.

The 72-week data show that 91% of HBeAg-negative and 79% of HBeAg-positive patients had levels of virus in the blood below 400 copies/mL. Safety was also a strong point, Prof Marcellin said. "Given that HIV patients have been taking this drug for six years, we know that it's safe."

In addition, the superiority of Viread over Gilead's own Hepsera treatment was emphasised by the finding that patients on the older drug with high levels of HCV in their blood showed a rapid response when switched to the newer treatment. Prof Marcellin said that combining the drug with standard interferon immunotherapy might provide even better results. "I believe that the combination of interferon and tenofovir could be synergistic," he said.

Another eminent hepatitis expert, Professor Jean-Michel Pawlotsky of the Henri Mondor Unversity Hospital, Creteil, Paris, said the latest results meant that older anti-virals were no longer the drugs of choice for HCV infection. "Lamivudine is cheap but we think that it should not be used as first-line treatment these days. The newer drugs like tenofovir are so much better," he said.

He noted that in contrast to Viread's continued efficacy, resistance to older anti-virals such as lamivudine was occurring in up to half of patients after three years. However, Prof Marcellin stressed that important questions regarding treatment had yet to be answered.

"The key questions we still have to answer are: who we should treat; when to start treatment and for how long to continue it," he said. He added that viral resistance to drugs and the problems posed by co-infection with HIV remained cause for concern.

Liver disease due to chronic HBV infection kills around 600,000 people a year around the world. Doctors hope that better drug treatment will prevent the constant liver inflammation that leads to cirrhosis or cancer in those infected.

Gilead is battling for market share with Bristol-Myers Squibb's Baraclude (entecavir). The latter has already demonstrated 90% viral suppression rates for up to 146 weeks.