GlaxoSmithKline could see healthy additions to its profit line if key trials throw up positive data, according to analysts from Collins Stewart. The UK giant's diabetes blockbuster Avandia looks set to become a £3 billion drug by 2010, while the asthma agent Advair could see its fortunes boosted to $5 billion a year by 2009 if results from eagerly awaited studies come to fruition.

The Avandia (rosiglitazone) portfolio of drugs is already a significant earner for the firm as GSK's second most-important drug by sales, pulling in £1.3 billion ($2.5 billion) in 2005. But new data from the DREAM study, due to be unveiled on September 15, could open a door to a massive new market in patients with a family history of the disease who are at high risk of developing diabetes. By combining Avandia with the heart drug ramipril to treat at-risk patients, the aim is that many will be prevented from going on to develop full-blown diabetes. The five-year study stemmed from a landmark investigation dubbed HOPE, which showed ramipril significantly cut the risk of death, heart attack and stroke, but - significantly - also showed the compound may have a positive effect on the progression of diabetes, with a 34% reduction in new diagnoses amongst the ramipril group.

Collins Stewart believes positive data from this study could see Avandia's sales ramped up to £2.6 billion by 2009 and £3 billion by 2010. And the data are crucial in another respect: fending off new rivals from that are looming on the horizon. The DPP-4 inhibitors, including Novartis' Galvus (vildagliptin) and Merck & Co's Januvia (sitagliptin), have both been submitted for approval and tipped to create a market valued at around $3 billion by analysts at Morgan Stanley. Merck is expecting to hear from the US Food and Drug Administration on its application by mid-October and is running a few months ahead of rival DPP-IV inhibitor Galvus (vildagliptin) from Novartis, which should reach the market next year.

Holding a TORCH for Advair

And on to Advair (fluticasone/salmeterol), GSK's number one drug, which rose 12% to £822 million in the second quarter of this year alone and pulled in full year 2005 sales of £3 billion. The company recently announced top-line results from the TORCH study, which involved more than 6,000 patients with chronic obstructive pulmonary disease across Europe. Advair is already sold for asthma and COPD, but Collins Stewart suggests some of the analyst community remain unconvinced as to its efficacy in reducing the mortality burden of COPD - the fourth leading cause of death in the Western world. The results of TORCH showed Advair reduced all-cause mortality by 17% in COPD patients over a three-year period compared to a placebo, although this narrowly missed achieving statistical significance.

More enticing details are due to be released in September, although full results will not be available until publication in a peer-reviewed journal in a few months' time. GSK hopes to file soon to include the mortality data in the labeling for Advair, which Collins Stewart says will likely lead to revenue upgrades for the drug. It is forecasting sales for Advair by 2009 of £4.8 billion and expects to see these figures boosted. News of the positive analyst comments lifted the firm's share price on the New York and London stock exchanges yesterday.

- Meanwhile, GSK says it has received European approval to use its antiviral drug Relenza (zanamivir) in the prevention of influenza in adults and children aged over five. Its treatment label has also been expanded from use in adults and adolescents aged over 12 to include children over the age of five. It's great news for GSK, which has struggled to develop a momentum behind Relenza in comparison to the extraordinary growth witnessed by Roche's Tamiflu (osteltamivir) in the wake of fears over a flu pandemic and avian flu.