Glaxo's "son of Advair" takes shape as rivals snap

By Ben Hirschler, European Pharmaceuticals Correspondent

LONDON, April 3 (Reuters) - GlaxoSmithKline Plc (GSK.L) has taken a step forward in developing a successor to its top-seller Advair, as rivals snap at its dominant position in respiratory medicine.

Industry analysts said positive mid-stage trials with a new inhaled long-acting beta agonist (LABA), announced late on Monday by U.S. partner Theravance Inc (THRX.O), showed Glaxo's replacement for Advair was taking shape.

The project is important because Advair could face generic competition in the key U.S. market in 2011, and life for Advair is about to get more competitive with the planned U.S. launch of AstraZeneca Plc's (AZN.L) rival Symbicort in mid-2007.

Advair, which sold 3.3 billion pounds ($6.5 billion) worldwide in 2006, combines two ingredients -- a steroid to fight inflammation and a beta agonist to open airways by relaxing muscles that tighten during an asthma attack.

Both elements will be replaced in the follow-on product, dubbed "son of Advair". But while the choice of steroid has been obvious for some time, the selection of a new LABA has until now been unclear.

Theravance said two LABAs tested as part of its alliance with Glaxo had both produced positive Phase II results but GSK642444 (444) given once day had proved better than Glaxo's older drug Serevent twice a day, while GSK159797 was comparable.

"This suggests that '444 could be a viable replacement component of the next generation Advair," analysts at Dresdner Kleinwort said in a note.

Glaxo shares were up 0.5 percent in a slightly firmer market for European drug stocks .SXDP by midday.

PHASE III TRIAL END-2008

A Glaxo spokesman said final Phase III clinical trials of the new combination would start at the end of next year.

Glaxo will pay royalties to Theravance on whichever LABA is taken to market.

David Beadle, an industry analyst with UBS, said the latest clinical results were a mild positive but he noted Glaxo still faced stiff competition from rivals racing to develop other improved combination asthma drugs.

Novartis AG (NOVN.VX), in particular, could be slightly ahead with its combination programme, Beadle said. Advair remains a pivotal driver for Glaxo's business in the short term, although its growth has slowed worryingly in the past year.

However, Glaxo is hoping for an upturn in prescriptions as physicians become educated about a new clinical trial, known as TORCH, which found a non-statistically significant reduction in mortality in patients with smoker's lung, or COPD.