Eligibility Of Monoclonal Antibody-based Therapy For Patients With Severe Asthma: A Canadian Perspective

RATIONALE: Worldwide, 5-25% of individuals have severe asthma, with major impact on health-related quality of life and resource utilization. Expanding knowledge of immunologic phenotypes has translated into increasing use of biologic therapies for severe, corticosteroid-refractory asthma. Based on clinical characteristics and approved indications, patients may qualify for one or both of these treatments. The epidemiology is not well characterized, particularly in the Canadian population.

METHODS: Our objective was to identify proportions and clinical characteristics of patients with severe asthma eligible for omalizumab (targeting IgE/allergic asthma), mepolizumab and/or reslizumab (targeting IL-5/eosinophilic asthma).

RESULTS: Of 128 patients with severe asthma, 84 (66%) were eligible for omalizumab, 100 (78%) for mepolizumab, and 52 (41%) for reslizumab. 68 (53%) patients were eligible for both omalizumab and mepolizumab, 52 (41%) were eligible for mepolizumab and reslizumab, and 37 (29%) were eligible for all three medications. The mean age (between 53-55 years), gender (between 63-68% female), and percent of predicted FEV1 (between 67-71) were similar between groups. 35 (42%), 38 (38%), and 24 (46%) patients in omalizumab, mepolizumab, and reslizumab eligible groups had asthma-related hospital presentations in the year prior to initiation of biologics.

CONCLUSIONS: In this Canadian cross-section, treatment eligibility for mepolizumab was higher than for reslizumab, based on the higher eosinophil threshold. Treatment eligibility for omalizumab was lower than mepolizumab, a finding that has not been replicated in other studies of biologic therapy for asthma. Personalizing therapy for asthmatic patient populations, and further development of biologics with favourable safety profiles, should lead to further advances in asthma management.