Researchers said that GlaxoSmithKline's experimental drug mepolizumab could help people with severe asthma who often have to take oral steroids to control their symptoms.

Two small studies reported in the New England Journal of Medicine said that the drug mepolizumab, also known as Bosatria, when taken regularly can reduce the number of asthma attacks in patients who did not get relief from oral corticosteroid treatment.

The studies were financed by GlaxoSmithKline, the pharmaceutical company that is developing the drug after tests on a broader group of asthma patients failed to produce major improvement.

They also reported that people on the drug were found to have lower levels of eosinophils, a type of white blood cell that has been implicated as a potential cause of asthma. The drug mepolizumab reduces the number of eosinophils by inhibiting an immune system signaling chemical called interleukin-5.

Dr. Ian Pavord, consultant physician and an honorary professor of medicine at Glenfield Hospital, University Hospitals of Leicester, England and senior author of one of the studies said, "This is a new treatment which substantially reduces the risk of asthma attacks in a severe asthma population."

Dr. Paul O'Byrne, the senior author of the other study is chairman of the Department of Medicine at McMaster University and executive director of the Firestone Institute for Respiratory Health at St. Joseph's Hospital in Hamilton, Ontario, Canada.

He added that "we now have a likely new treatment modality that will improve outcomes and reduce exacerbations in severe prednisone-dependent asthma, and this is not a small population -- it's probably 2 to 4 percent of the asthmatic population. This is a very difficult-to-manage group of asthmatics. These are people who are already on a lot of asthma medications and are also taking oral corticosteroids on a maintenance basis to try to control the symptoms they're having."

He and his colleagues reported that the drug reduced the need for oral steroids. O'Byrne said, "It had a very dramatic benefit in these patients. Most of the patients came off the oral steroids, which they had been on for about 10 years, and they did not have a flare-up or an exacerbation of their asthma control. For the folks who took the placebo, we were able to reduce their oral steroid load, but in all but one or two people, this was associated with a worsening of their asthma control."

Pavrod and his colleagues in the study randomly divided 61 people with severe asthma into two groups and gave one group 750 milligrams of mepolizumab and the other a placebo intravenously once a month for a year.
 
They reported that the group on mepolizumab had fewer asthma exacerbations than those on placebo in the ratio of 2 versus 3.4 and the drug users also reported a greater improvement in their quality of life than did people taking the placebo.

The second study included 20 patients who had severe, prednisone-dependent asthma. Prednisone is an oral steroid that is generally quite effective in treating asthma but has numerous and serious side effects.  Of them nine were given intravenous doses once a month of 750 mg of mepolizumab while 11 who were given intravenous doses once a month of a placebo.

In the six month trial 12 cases of asthma exacerbations were seen in 10 people on placebo and nine had evidence of eosinophils during their exacerbations. In the study period only one person in the treatment group had an exacerbation, but no eosinophils were present and this group was able to reduce their dosage of prednisone more than people on placebo could.

Both the studies did not link mepolizumab with a serious side effect, though both authors pointed out that the studies were small and no more than six months to a year long.

Dr. Sally Wenzel, director of the Asthma and Allergy Center at the University of Pittsburgh Medical Center said, "If you are one of those people [who has eosinophils] and your asthma is pretty severe, this may be a relatively promising treatment to prevent exacerbations, though it's still experimental." (Harkiran contributed to this report)