Japanese subphenotypes of type 2 severe asthma identified
medwireNews: The majority of Japanese patients with severe, difficult-to-treat asthma are likely to present with type 2 asthma and a substantial proportion overlap between two or more subphenotypes, a study suggests.
Researchers found that more than 80% of the Japanese adults studied could be classified as having one or more of the following: eosinophilic, periostin-high, or atopic asthma.
The findings come from 144 adult patients recruited from 18 hospitals in Japan with difficult-to-treat asthma, defined as disease that requires Global Initiative for Asthma step 4 or 5 treatment under the management of certified pulmonologists or allergists.
Masako Matsusaka (Keio University School of Medicine, Tokyo, Japan) and colleagues report that, despite a modest correlation between peripheral blood eosinophil counts and serum periostin levels, these values did not relate to one another in some patients.
Patients were therefore divided using the tentative cutoff values of 300 cells/μl for peripheral blood eosinophil counts and 95 ng/ml for serum periostin levels.
This identified 59 patients with low eosinophils-low periostin (LE-LP), 45 with high eosinophils-low periostin (HE-LP), 10 with low eosinophils-high periostin (LE-HP), and 30 with high eosinophils-high periostin (HE-HP).
Patients with periostin-high asthma shared similar clinical characteristics, including a higher prevalence of late-onset asthma, self-reported olfactory dysfunction, and leaner body mass, irrespective of whether they had high or low levels of peripheral blood eosinophils.
The major difference between the LE-HP and HE-HP subgroups was the higher use of regular oral corticosteroids in the LE-HP subgroup, at rates of 60.0% and 36.7%, respectively.
There was no difference in the rate of oral corticosteroid use between the low-periostin groups, which included more patients with early-onset atopic asthma.
Furthermore, on the basis of the levels of biomarkers including total/allergen-specific immunoglobulin E, peripheral blood eosinophil counts, and serum periostin levels, the researchers found that just 17% of the patients had no indication for type 2 T helper cell (TH2)-targeted drugs, even under what they describe as “relatively strict cut-off values for the biomarkers.”
Conversely, just over a third (37%) were candidates for two or three different types of TH2-targeted agents.
Reporting in The Journal of Allergy and Clinical Immunology: In Practice, the study authors conclude: “Using multiple biomarkers for subphenotyping type 2 asthma would improve clinical characterization and may increase the possibility of using combined TH2-targeted therapies in cases refractory to standard treatment approaches.”
By Anita Chakraverty
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