US researchers say that a novel approach to obstructing the runaway inflammatory response implicated in some types of asthma has shown promise in a Phase IIa clinical trial.
Their research will be presented at the American Thoracic Society 2013 International Conference and published simultaneously online in the New England Journal of Medicine
The randomized, double-blind, placebo-controlled trial tested the efficacy and safety of the monoclonal antibody, dupilumab, in patients with "persistent, moderate-to-severe asthma" and elevated eosinophils, which are immune cells that mobilize in response to allergens and infections and are commonly seen in asthma.
According to lead author Sally Wenzel, MD, director of the University of Pittsburgh Asthma Institute, the combination of inhaled glucocorticosteroids (ICS) and long-acting beta agonists (LABA), which is a cornerstone of asthma controller therapy, does not work sufficiently in 10 to 20 percent of asthma patients in the United States.
"Asthma that is difficult to treat is increasingly recognized as comprising different phenotypes," she said. "With this study, we wanted to see whether dupilumab would reduce a surrogate index for asthma exacerbations when given with ICS and LABA and when those two therapies were withdrawn."
Dupilumab, a fully human monoclonal antibody discovered by Regeneron Pharmaceuticals and being developed by Regeneron and Sanofi, thwarts activation of the Th2 immune response implicated in asthma by blocking two cytokines, interleukin-4 and interleukin-13.
Over the course of a 12-week blinded treatment period and an 8-week follow-up, those patients who had received weekly injections of dupilumab experienced an 87 percent reduction in protocol defined asthma exacerbations, the primary endpoint of the study, vs. weekly placebo injections (odds ratio [95% CI]=0.08 [0.021 to 0.28]; p<0.01). Significant improvements were also reported for other relevant asthma outcomes such as lung function as assessed by forced expiratory volume in one second (FEV1) and morning peak expiratory flow, asthma symptoms and control, as well as, asthma reliever medication use. Many of these improvements were seen when dupilumab was added to ICS/LABA, with efficacy maintained despite background therapy withdrawal.
"Intriguingly," noted Dr. Wenzel, "dupilumab showed substantial efficacy in objective and patient-reported endpoints when added to ICS and LABA and when those therapies were discontinued."
Patients in the study received dupilumab or placebo added to their regular, twice daily dose of fluticasone/salmeterol. At Week 4, patients were instructed to withdraw the LABA (salmeterol). Between Weeks 6 and 9, they tapered off fluticasone, the ICS.
A total of 104 patients, aged 18 to 65, participated in the study. Half received the monoclonal antibody; half received placebo. All had persistent, moderate-to-severe asthma that was not well-controlled by medium to high doses of combined ICS and LABA therapy. The patients also had elevated blood (≥ 300 cells/ĩl) or sputum (≥3%) eosinophils at screening.
The study found no clear change in blood eosinophils with dupilumab therapy; however, other biomarkers decreased, including fractional exhaled nitric oxide, thymus and activation regulated chemokine, immunoglobulin E and eotaxin-3, confirming the biologic activity of dupilumab.
Side effects occurring more frequently in the patients receiving the monoclonal antibody vs. placebo included injection site reactions, nasopharyngitis, nausea and headache, but were not considered severe.
According to Dr. Wenzel, the current study, exhibited a "magnitude and breadth" of efficacy that exceeded other studies of cytokine inhibition in asthma. She and her investigator colleagues speculate that the stronger outcome came as a result of blocking two cytokines, IL-4 and IL-13, rather than a single one.
They called for further studies to confirm these observations and better define the target population, dosing regimen, and long-term efficacy and safety
The trial was sponsored by Sanofi and Regeneron.