The drug, benralizumab, is a biologic that works by killing white blood cells called eosinophils. These are present in large numbers in such patients, and they have been linked to severe asthma.
If approved by the U.S. Food and Drug Administration, benralizumab would join two similar drugs -- mepolizumab (Nucala) and reslizumab (Cinqair) -- in fighting hard-to-control asthma, the researchers said.
"We can offer patients who frequently require courses of oral corticosteroids and have a certain level of eosinophils [an allergy-related cell easily measured in the blood] a very effective treatment," said study author Dr. J. Mark FitzGerald. He is a professor of respiratory health at the University of British Columbia in Vancouver.
"With the right patient with the right characteristics, we can significantly modify the level of asthma severity," added FitzGerald, who had a hand in both trials.
The studies were funded by AstraZeneca, the maker of benralizumab, and published online Monday in The Lancet, to coincide with the presentation of the findings at the European Respiratory Society meeting in London.
FitzGerald reports serving as a consultant to AstraZeneca.
One potential advantage of benralizumab is that it can be given less often, said Dr. Mario Castro, a professor of medicine and pediatrics at Washington University School of Medicine in St. Louis.
"The treatments that we have now are done every two weeks or once a month, but benralizumab can be given every two months, which may lower the cost," he said.
The available drugs cost about $25,000 to $30,000 a year and are covered by insurance, including Medicare, said Castro, who co-authored an editorial accompanying the trial reports.
The current drugs have been approved for patients age 12 and older, "but we are very interested in them moving to the next lower age range of 6 and above," he said.
"If you have severe asthma and you're not getting the control that you need, ask your doctor about these medications," Castro suggested.
In the first trial, more than 1,300 patients age 12 to 75 were randomly assigned to one of three groups: benralizumab given every four weeks; benralizumab given every eight weeks; or a placebo. In addition, the patients continued to use high-dose inhaled corticosteroids and long-acting beta agonists inhalers to control their asthma.
Over 52 weeks, the researchers found that patients taking benralizumab had a 28 percent to 36 percent reduction in flare-ups, compared with a placebo. Patients on benralizumab also showed improved lung function.
The most common side effects were cold-like symptoms in 20 percent of those receiving benralizumab, versus 21 percent of those on a placebo, and worsening asthma, 12 percent versus 15 percent, respectively.
Four patients suffered from serious side effects, including one case of hives and two cases of herpes. One patient who was taking a placebo suffered chest pains. Because of side effects, seven patients receiving benralizumab and three receiving a placebo dropped out of the trial.
"About 10 percent of patients with asthma have severe disease, which flares in spite of current maximal therapies," said Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York City.
Compared with Nucala and Cinqair, benralizumab appears to work in a different way by reducing the number of eosinophils, cells that cause asthma, he said.
"Immune modulation has been on the forefront in treating many diseases, including cancer, but this drug represents a step forward in treating asthma," Horovitz said.
In the second trial, more than 1,200 patients were assigned to similar groups as in the first trial. The researchers found that benralizumab cut asthma flare-ups by 45 percent to 51 percent, compared with a placebo.
The most common side effects were worsening asthma in 13 percent of those receiving benralizumab, compared to 12 percent of those receiving a placebo, and cold-like symptoms experienced by 12 percent of patients in both groups.
Among patients taking benralizumab, four suffered serious side effects. One patient had allergic granulomatous (inflammation of blood vessels), one patient had a panic attack and one had paresthesia (pins and needles). Among those receiving the placebo, one had a skin reaction at the site of the injection. In all, 18 patients receiving benralizumab and three receiving a placebo dropped out of the study due to side effects, the researchers said.
One respiratory disease expert sees this new drug as another breakthrough in treating hard-to-control asthma.
"These biologicals treat patients that were previously untreatable, and these treatments are getting better and better," said Dr. Alan Mensch, chief of pulmonary medicine at Northwell Health's Plainview Hospital in New York.
For more on asthma, visit the U.S. National Heart, Lung and Blood Institute.
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