Patients with Lower Eosinophil Counts Can Still Benefit from Mepolizumab

Mepolizumab has been shown to decrease high blood eosinophil counts in severe asthma, but no specific number has been established at which the treatment is recommended. A new study has shed more light on that question, showing that patients suffering severe asthma with lower eosinophil counts may also benefit from mepolizumab treatment.

Mepolizumab (NUCALA) is an injection given once every 4 weeks that impedes the production of interleukin-5 (IL-5), the cytokine responsible for releasing eosinophils into the blood or tissues. During clinical trials, mepolizumab lowered blood eosinophil counts in patients with severe asthma, reduced the need for oral corticosteroids (OCS), and improved lung function.

Investigators—led by Steven W. Yancey, MSc, of GlaxoSmithKline’s (GSK) Respiratory Therapeutic Area—analyzed 4 clinical trials involving mepolizumab: DREAM, MENSA, SIRIUS, and MUSCA. A total of 1883 subjects with severe eosinophilic asthma were randomized to receive mepolizumab or placebo. Dose amounts included 100 mg subcutaneously, 75 mg intravenously (IV), 250 mg IV, or 750 mg IV. All patients were being treated with the highest standard of care to control asthma and were at high risk for asthma exacerbations.

For those whose blood eosinophil counts were between 150-300 cells/μL and greater than 300 cells/μL, investigators evaluated how many were on maintenance OCS, had a surge in OCS use within the previous 12 months, had an emergency room (ER) visit within the previous 12 months, an intubation for an asthma exacerbation within the previous 12 months, a near fatal asthma event in their lifetime, and the number of clinically diagnosed exacerbations.

Exacerbation rate reductions were examined for patients whose blood eosinophil counts were between 150-300 cells/μL in DREAM, MENSA, and MUSCA at baseline; reduction in OCS use was analyzed in SIRUS patients for those with a blood eosinophil count of 300 cells/μL or greater at baseline.

There was no significant difference in morbidity, asthma related ER visits, near fatal events, exacerbation rates, and maintenance OCS among patients with blood eosinophil counts between 150-300 cells/μL and 300 cells/μL or greater.

For patients in MENSA, DREAM, and MUSCA with blood eosinophil counts between 150-300 cells/μL, exacerbation reduction rates fluctuated between 27% and 49%. In SIRUS, the likelihood of a reduction in OCS use was 2.03 (95% CI: 0.53-7.75) for patients with blood eosinophil counts of 150-300 cells/μL, compared to 1.79 (95% CI: 0.71-4.52) in patients with blood eosinophil counts of 300 cells/μL or greater.

“The reduction achieved with mepolizumab in this challenging patient population at high risk of exacerbations is clinically important,” investigators noted. “A substantial proportion of patients with severe eosinophilic asthma, who could potentially reduce their corticosteroid intake, would miss out on the benefits of mepolizumab if a threshold of 300 cells/μL or greater was used for treatment eligibility.”

A continued limitation to mepolizumab being more highly recommended to patients is its cost. In a statement acknowledging costs to access, Yancey told MD Magazine® that GSK is committed to providing coverage support and cost responsibility assistance.

“For example, commercially covered patients may be able to get help with their out-of-pocket costs through our Co-Pay Program, he said. “Uninsured patients may be eligible for our Patient Assistance Program, which provides medicines at no cost for those who qualify.”

The study, “Disease Burden and Efficacy of Mepolizumab in Patients with Severe Asthma and Blood Eosinophil counts of 150-300 cells/μL,” was published online in Respiratory Medicine.