The House of Lords threw out an appeal by Biogen attempting to overturn an earlier ruling by the Court of Appeal that Medeva's drug, Hepagene, did not infringe its patent over a similar treatment.
Alexandra Hockenhull, a Medeva spokeswoman, said: "The outcome sends a very strong signal. We had felt extremely confident all along. We had a decisive victory in the appeal court and now, with another decisive victory in the House of Lords, we feel even more confident."
The group still faces a separate patent infringement action over Hepagene filed in 1993 by Pasteur-Merieux, a French drugs group. However, it had not proceeded "expeditiously" with the claim, she said, and a trial date had not yet been requested or set.
The drug, which is still under development, was acquired for a little over pounds 3m by Medeva in 1992 from a group of Swiss and German scientists known as Epitec.
Biogen, whose own Hepatitis B vaccine is licensed to SmithKline Beecham and Merck, won an action against Medeva in the High Court in 1993. But the House of Lords ruled yesterday that Biogen's patent was invalid in the UK.
Medeva said it hoped to announce the results of phase three trials of Hepagene as a vaccine in January, with phase two proof of principal tests on its effectiveness as a treatment due by the end of this year. Estimates suggest that around 30 million people in the world carrying the Hepatitis B virus are highly infectious.
Biogen's chief executive, Jim Vincent, said: "Although we expect to continue receiving our UK royalties of less than a million dollars annually based on the surviving Hepatitis B patent, we are clearly disappointed by today's decision."Reuse content