Over the study period, those on mepolizumab had fewer asthma exacerbations than those on placebo -- 2 versus 3.4. People taking the drug also reported a greater improvement in their quality of life than did people taking the placebo.
The second study was smaller, including just 20 patients. Nine received 750 mg of mepolizumab, and 11 were given a placebo. Again, the drug and placebo were administered in intravenous doses once a month.
Everyone in this study 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.
In the six-month trial, there were 12 asthma exacerbations in 10 people on placebo. Nine had evidence of eosinophils during their exacerbations. During the study, just one person in the treatment group had an exacerbation, but no eosinophils were present. Additionally, those taking the drug were able to reduce their dosage of prednisone more than people on placebo could.
Mepolizumab was not associated with a serious side effect in either study, though both authors pointed out that the studies were small and no more than six months to a year long.
"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," said the author of an accompanying editorial in the same issue of the journal, Dr. Sally Wenzel, director of the Asthma and Allergy Center at the University of Pittsburgh Medical Center.
But, she pointed out that not everyone who has asthma also has eosinophils.
All three experts said they were not sure if mepolizumab would have a place in treating less severe asthma, at least for awhile.
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