LONDON (Reuters) - A new kind of injectable biotech treatment for severe asthma from AstraZeneca and Amgen promises to help a much broader range of patients than existing medicines like GlaxoSmithKline’s Nucala.

FILE PHOTO: The logo of AstraZeneca is seen on medication packages in a pharmacy in London, Britain April 28, 2014. REUTERS/Stefan Wermuth /File Photo

Findings from a mid-stage clinical trial involving 584 patients showed on Wednesday the experimental drug tezepelumab reduced the annual rate of serious asthma attacks, known as exacerbations, by between 61 and 71 percent, depending on dose.

The results could put the first-in-class injection in a strong position in a competitive market as it heads into final-stage Phase III tests later this year or early next.

“Tezepelumab appears to be the broadest and most promising biologic for the treatment of persistent uncontrolled asthma to date,” Elisabeth Bel of Amsterdam’s Academic Medical Center wrote in an editorial in the New England Journal of Medicine.

Still, she cautioned researchers needed to confirm its safety profile in larger trials, since there was a potential risk its impact on the immune system might lead to infections.

Shares in AstraZeneca rose 1 percent on Thursday following the news, with Barclays analysts citing it as an example of the strength of the drugs pipeline beyond cancer, which will be in focus at a medical meeting in Madrid this weekend.

Injections for severe asthma have opened up a multibillion-dollar market as competing drugmakers have raced to develop antibody-based medicines for the 15 percent or more of patients who do poorly even on the latest inhalers.

Despite treatment advances in recent decades, their asthma is still not well controlled by standard therapy, which consists of inhaled steroids and drugs to open the airways.

Nucala and Teva’s Cinqair are two recently approved new injectable drugs and AstraZeneca’s benralizumab is likely to join them soon, since it is awaiting approval in the fourth quarter of this year.

Sanofi’s Dupixent, already approved for severe eczema, is a bit further behind but is widely seen as a strong contender.

However, all these new medicines only appear to help people with certain types of severe asthma, by targeting specific inflammatory chemicals made in the body that drive asthma, making them suitable for subgroups of patients.

Tezepelumab is different because it acts further upstream in the inflammatory cascade responsible for asthma by blocking the action of a cell-signalling protein called thymic stromal lymphopoietin (TSLP).

That means it can help a wider range of patients and could be a “game-changer”, according Tom Keith-Roach, head of AstraZeneca’s respiratory, inflammation and autoimmune business.

Biotech drugs for severe asthma are already worth $2 billion in annual sales and Keith-Roach believes there is significant scope for growth since currently only about 10 percent of patients who might benefit are getting them.

Tezepelumab, like Dupixent, is also being developed for eczema.

The results of the Phase IIb asthma study, which were published online by the New England Journal of Medicine, will also be presented at the European Respiratory Society annual meeting in Milan next week.