Selection of Biologics for Type 2–High Asthma

To the Editor:

We read with great interest the review article by McGregor and colleagues. The authors have reviewed the mechanism of action, indications, expected benefits, and adverse effects of each of the currently approved biologics for severe uncontrolled asthma (1). We would like to thank McGregor and colleagues for their contribution to literature with such a valuable review.

The authors say that “a recent pragmatic trial of omalizumab demonstrated similar benefits in T2-high and -low patients (AEC <300 or ≥300 cells/μl and fractional exhaled nitric oxide [Fe_NO] <25 or ≥25 ppb).” However, we think that describing the patient population of this study as type 2 (T2)-high and -low patients may cause confusion because we should not evaluate the atopic asthma (in which asthma is clinically allergen driven) independently from T2-high asthma. Allergic (atopic) asthma is also part of the T2-high asthma (2). The authors of the study have already described the patient groups as high-biomarker subgroups and low-biomarker subgroups, not T2 high and low (2).

Another point the authors have mentioned is that omalizumab has no biomarker that has been useful for predicting or monitoring response. However, some potential predictors of good response to omalizumab have been recommended in the GINA (Global Initiative for Asthma) severe asthma guidelines such as blood eosinophils ≥ 260/μl, Fe_NO ≥ 20 ppb, childhood-onset asthma, and clinical history suggesting allergen-driven symptoms (3).

In conclusion, current biologics for T2-high severe asthma should be chosen wisely according to some logical recommendations, which can be made at this time on the basis of the mechanisms of the action of the drugs and the underlying pathophysiology of various asthma phenotypes, until validated biomarkers are detected for the selection of biologics.