An experimental drug called mepolizumab can prevent severe asthma attacks in people with an uncommon form of the disease that responds poorly to standard steroid medications, researchers report in two studies in the March 5 New England Journal of Medicine.Scientists from Britain and Canada also find that a simple test of sputum (coughed up matter) can reveal which patients would most likely benefit from mepolizumab. Thus the drug might help some people with asthma reduce the use of steroids such