The drug, lebrikizumab, targets a specific receptor involved in asthma, and appears to be the first drug to be successful in this particular approach, said Dr Steve Georas, a professor of medicine in the pulmonary and critical care division at the University of Rochester Medical Center.
It is also perhaps the first drug to have this specific effect in asthmatics, and may lead to more gains in individualised treatments for patients.
"Personalised medicine hasn't made huge strides in asthma," said Georas. "We're all hopeful we're on the verge of a new era in that regard. This appears to be a first tentative step in that direction."
Georas was not involved with the new research, which appears in the New England Journal of Medicine and was funded by Genentech, which makes lebrikizumab.
Lebrikizumab is a monoclonal antibody that binds to interleukin-13 (IL-13), a signaling molecule involved in the inflammatory responses associated with asthma.
Although glucocorticoids also inhibit IL-13, the molecule manages to exert its influence in other ways which, so far, have eluded current medications. But, lebrikizumab works in a different way than traditional steroids.
How the study was done
The authors randomised 219 adults who had not responded to standard asthma treatments to receive either lebrikizumab or a placebo.
After three months, the overall group of patients taking lebrikizumab saw a 5.5% improvement in their FEV1 (forced expiratory volume in one second), which measures how much a person expels when exhaling, compared to the placebo group.
Patients who had high IL-13 levels (as measured by the protein periostin, which is produced by IL-13) saw an FEV1 improvement of 8.2 percent with lebrikizumab versus the placebo.
By contrast, in the low-periostin group, the improvement was only 1.6% higher.
While overall side effects were roughly the same in both groups, there were more musculoskeletal effects in the lebrikizumab group (13.2% in the treatment arm versus 5.4% in the placebo group).
In addition to the fact that the drug is not yet approved, lebrikizumab may have other issues.
For one thing, it's not clear if clinics can easily measure levels of periostin, said Georas. That would be key in determining who would and who wouldn't benefit from the drug.
Also, lebrikizumab is given as an injection once a month, something that many patients are reluctant to do. Even inhaled medications - especially glucocorticoids which can take days or weeks to help -- aren't overly popular with patients, said Dr. Susanna Von Essen, a professor of pulmonary and critical care medicine at the University of Nebraska Medical Center in Omaha.
"People like pills better than inhaled medications and usually injections are down the list but, if it causes improvement, you will find some patients who will accept it," she said.
Also, this breaks new ground in blocking IL-13 so "maybe this will be the beginning of a series of medications that attack the IL-13 molecule and maybe they'll come up with something inhaled or something you can swallow," she said.
The American Lung Association has more on asthma.
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