Novartis and Idenix Pharmaceuticals have filed for approval of a new hepatitis B treatment, telbivudine, in the USA.

This is the first regulatory submission of telbivudine, which has been tipped as a big seller after clinical data suggested it was more effective in tackling chronic hepatitis B than GlaxoSmithKline’s Zeffix (lamivudine), currently a standard treatment for the infection.

The application is based on the results of the GLOBE study, which found that Novartis' drug was better than lamivudine at reducing hepatitis B virus DNA, a marker for the presence of the virus in the blood. After a year's treatment HBV was undetectable in 60% of telbivudine patients, compared to 40% of the lamivudine group.

Novartis and Idenix are seeking approval of a 600mg, once-daily oral dose of telbivudine for the treatment of chronic hepatitis B. Additional regulatory filings will take place in Europe and some markets in Asia in the coming months, said the firms.

Telbivudine is one of the products predicted by market research firm Decision Resources to drive growth in the overall market for antiviral drugs for hepatitis B from a level of under $1 billion at present to around $3 billion by 2012. At present, Zeffix leads the market for oral hepatitis B drugs with sales of $191 million in the first nine months of 2005. Another product, Gilead Sciences’ Hepsera (adefovir dipivoxil), made about $135 million in the same period. The remainder of the market is largely accounted for by injectable interferon alpha products.

Analysts have estimated that telbivudine could achieve sales of around $400 million a year, helped by its improved ability to cause seroconversion in patients with HBe-antigen-positive infection. This type of hepatitis B is associated with a poor prognosis and drugs that can treat it are desperately needed. Telbivudine could also be helped by data showing it is effective in combination with lamivudine and so could help prevent viral resistance.

Other orally-active antivirals that will drive the hepatitis B market include Bristol-Myers Squibb's Baraclude (entacavir) and Gilead's clevudine, according to Datamonitor, which adds that the newer long-acting forms of interferon alpha, notably Roche’s Pegasys (peginterferon alpha-2a) will also make gains.

Meanwhile, Idenix and Novartis are also developing another hepatitis B drug, valtorcitabine, under the terms of a development and commercialization alliance signed in May 2003. The companies plan to co-promote the two drugs in the USA, UK, France, Germany, Italy, and Spain, with Novartis having exclusive rights elsewhere.