* Results of SUMMIT trial with Breo due as early as Sept
* Drug could be first to extend lives in COPD
* Billions of dollars riding on positive outcome
* U.S. partner Theravance eligible for royalties on sales
By Ben Hirschler
LONDON, Aug 13 (Reuters) - GlaxoSmithKline isbanking on a major clinical trial to revive its flaggingrespiratory medicine business, with billions of dollars of salesriding on a positive result.
Data from the so-called SUMMIT study, designed to show GSK'sBreo can prolong lives of patients with chronic lung disease,are expected as early as next month, nine years after a similarstudy with GSK's older drug Advair failed by a whisker.
This time GSK reckons it has a better chance, since the newtrial, with 16,500 patients, has more statistical power than the6,100-patient Advair trial, known as TORCH. GSK has also chosenhigher-risk patients with heart issues for the new study.
At present, inhaled drugs such as Breo that combine asteroid and a long-acting beta agonist (LABA) are known to helppatients breath more easily but their effect on survival isunclear.
If it succeeds, Breo would be the first drug to show asurvival benefit in patients with chronic obstructive pulmonarydisease (COPD), potentially turning around its fortunes.
While Breo was approved for COPD in 2013 and won a U.S.green light for asthma in April, it has been slow to take offcommercially.
Sometimes known as "son of Advair", once-a-day Breo has adosing advantage over twice-daily Advair. But the market forinhaled lung drugs is fiercely competitive and Breo hasstruggled at a time when GSK has been forced to cut Advairprices.
HSBC analyst Stephen McGarry thinks Breo could eventuallyachieve peak annual sales of $5.0 billion if SUMMIT succeeds, or$1.8 billion if it fails.
Other analysts are more cautious and the current consensusis for sales of $1.55 billion in 2020, according to ThomsonReuters Cortellis.
GSK's partner Theravance is entitled to royaltiesof 15 percent on the first $3 billion of annual sales and 5percent beyond that.
Britain's GSK has been a world leader in respiratorymedicine since launching the Ventolin inhaler back in 1969, butweak sales in recent quarters are a mounting concern for itsinvestors.
Courtney Crimm, a pulmonologist who oversees the SUMMITtrial at GSK, believes a successful result would oblige doctorsto rethink prescribing strategies.
"If this study is positive, it could lead to a paradigmshift," he told Reuters, noting that 50 to 70 percent of COPDpatients also have cardiovascular risk factors.
Furthermore, because SUMMIT recruited patients with"moderate" COPD it might prompt wider use of the medicine inpatients with less severe breathing difficulties, he said.
Current medical guidelines recommend steroid and LABAcombinations only for people with more severe breathingproblems. Those who are less seriously affected are often givenan alternative drug such as Pfizer and BoehringerIngelheim's Spiriva. (Editing by Mark Potter)
Glaxosmithkline (GSK)