* Goal to help some 2 million patients with severe asthma
* GSK leads new wave with mepolizumab due for 2014 filing
* Rivals include Roche, AstraZeneca, Sanofi and Teva
* Potential $7.5 billion market seen for severe asthma drugs
LONDON, March 18 (Reuters) - Rival firms are racing to develop injectable biotech asthma drugs for patients with severe disease who don't respond well to traditional inhalers, in pursuit of a new market worth a possible $7.5 billion.
Britain's GlaxoSmithKline, the leader in asthma treatments since launching its Ventolin inhaler in 1969, is in the vanguard but faces competition from the likes of Roche , AstraZeneca, Sanofi and Teva .
Despite treatment advances in recent decades, asthma is still not well controlled in up to 20 percent of patients on standard therapy, which consists of inhaled steroids and long-acting beta agonists that are designed to open the airways.
This patient group includes many with severe disease, thought to number around 2 million in leading industrialised nations, according to consultancy Decision Resources.
Novel antibody-based drugs now nearing the market offer a way to get to the root of the problem by targeting key inflammatory chemicals made in the body that drive asthma. They are already being hailed by doctors as a major advance.
"I'm very optimistic about the new drugs," said Elisabeth Bel, president-elect of the European Respiratory Society and head of respiratory medicine at the Academic Medical Centre in Amsterdam.
"We have participated in several trials with the new biological agents and have seen some amazing results."
In particular, the new injectable medicines have led to reductions in serious asthma attacks, known as exacerbations, of around 40 to 60 percent in clinical trials.
The threat of such attacks - which may require hospital treatment and can sometimes be life-threatening - dominate the lives of people with severe asthma and represent a big financial burden to healthcare systems providing emergency care.
WHAT PRICE PERSONALISED MEDICINE?
Significantly, the new drugs offer a more personalised approach to asthma care, with patients undergoing so-called "biomarker" blood tests to check if they are likely to respond to the medicines.
This targeted approach is gaining traction in many medical fields, most notably cancer. It is attractive to governments and insurers who pay for healthcare, since it means drugs should only go to patients who are likely to benefit.
"Severe asthma patients represent the majority of the (asthma) burden on healthcare systems and budgets," said Bahija Jallal, head of AstraZeneca's MedImmune biotech unit, which is investing in a broad portfolio of medicines for the condition.
"We will be working to convince payers this is something that brings value."
Coupled with the money hospitals could save from a big drop in exacerbations, this leads many analysts to argue that companies will be able to charge a high price for the new drugs.
Barclays analysts, for example, assume a price of around $15,000 a year for GSK's new drug mepolizumab, which is set to be submitted for regulatory approval later this year following positive late-stage study results last week.
Seamus Fernandez of Leerink, who predicts the market for severe asthma biotech drugs could exceed $7.5 billion a year in the United States and Europe alone, is more cautious and expects a price tag of something under $10,000, reflecting an increasingly competitive landscape.
That would be a modest discount to the price of Xolair, from Novartis and Roche, which is the only biotech asthma drug sold at present, but which works in a different way to the new batch of products and is only indicated for allergic asthma.
Some doctors are wary about the pricing environment.
"I think cost is going to be a hurdle. Payers are going to have to figure out whether they are going to allow multiple patients to be on multiple biologics," said Michael Wechsler, an asthma specialist at National Jewish Health in Denver.
Although the number of patients with severe asthma is small, there are at least five known disease sub-types, depending on which precise biological pathways are driving the condition.
Working out the right drug for the right patient is therefore going to be a challenge, according to Wechsler, who believes there is still more work to be done on tests, since biomarker signals can be transient within individual patients, depending on their condition and medicines they are taking.
Analysts reckon GSK is two years ahead of rivals with its drug to block the action of inflammatory chemical interleukin-5 (IL-5), with competition coming from AstraZeneca and Teva.
But IL-5 is not the only game in town. Experimental products from Sanofi, working with Regeneron, and Roche target two chemicals known as IL-4 and IL-13, which might have an even greater impact.
GSK hopes to get a commercial edge by being ahead of the pack, but the company acknowledges that picking the right drug for the right patient will not be straightforward.
"There will be some overlap where some patients could be effectively treated with one or more drug, but there are likely to be others who are only effectively treated with one type. It's still early days to sort through all of that," said Steve Yancy, GSK's development leader for mepolizumab.