Masitinib Shows Promise in Reducing Severe Asthma Exacerbations

Pascal Chanez, MD, PhD

According to a new phase 3 study, masitinib significantly decreased the rate of severe asthma exacerbations among patients who experienced little to no relief with oral corticosteroids (OCS). Improvements were achieved regardless of eosinophil level.

These findings will be presented this week at an American Thoracic Society (ATS 2020) symposium as a late breaking clinical trial.

The AB07015 study, led by Pascal Chanez, MD, PhD, Professor of Respiratory Diseases, Aix-Marseille University, France, was a randomized, double-blinded, placebo-controlled trial that evaluated the efficacy of 6 mg/kg/day of masitinib treatment for severe persistent asthma.

Masitinib is a first-in-class drug in severe asthma that selectively targets mast cells through inhibition of tyrosine kinases c-Kit, LYN, and FYN. Previous research has demonstrated the therapeutic potential of and rationale for targeting mast cells in asthma.

However, the AB07015 trial was the first positive large-scale study in severe asthma utilizing a drug of this kind.

In the study, they enrolled a total of 355 patients in their primary analysis population. They especially noted patients with an initial eosinophil count of ≥150 cells/μL, which the investigators considered a key subgroup for their analysis. 

Following enrollment, patients were randomized 2:1 to receive either masitinib or placebo for 36 weeks, with a possible extension period until at least week 96.

Baseline characteristics and average exposure times (60 weeks) were well-balanced across treatment arms, the investigators noted.

Thus, the primary endpoint for the study was a reduction of annualized severe asthma exacerbation rate for overall exposure. They defined a severe asthma exacerbation event as worsening asthma leading to an increase from stable maintenance dose of corticosteroids for ≥3 days or hospitalization.

Following the treatment period, Chanez and team reported that masitinib significantly reduced the severe asthma exacerbation rate by 35% compared with placebo (rate ratio, 0.64 [95% CI, 0.48-0.84; P = .0014]).

Additionally, the eosinophil ≥150 cells/μL subpopulation demonstrated a significant reduction in severe exacerbations by 38% (rate ratio, 0.69 [95% CI, 0.49-0.95; P = .0249]).

The investigators also assessed a safety population — which included 404 patients, all of whom received at least 1 dose of the investigative drug, which included low-dosage (≤5mg/day).

In this population, 83.4% of masitinib users experienced ≥1 adverse events—compared with 82.0% in placebo users.

The rates for serious and severe adverse events for masitinib were 17.7% and 16.5%, respectively. For placebo, these rates were 48.0% and 45.9%, respectively.

“Masitinib, a first-in- class tyrosine kinase inhibitor targeting mast cell activity in severe asthma patients, demonstrated a positive benefit/risk ratio over a sustained period and may provide a new treatment option in severe asthma, irrespective of baseline eosinophil level,” the investigators concluded.

The study, “Masitinib Significantly Decreases the Rate of Asthma Exacerbations in Patients with Severe Asthma Uncontrolled by Oral Corticosteroids: A Phase 3 Multicenter Study,” was presented at ATS 2020 International Conference.