Could Eosinophil Count Predict Omalizumab Effectiveness?

Omalizumab has similar effectiveness among patients with severe allergic asthma (SAA) and high and low eosinophil subgroups, according to the results of a recent study.

In order to determine whether pre-treatment blood eosinophil count could be used as a predictive measure of response to omalizumab treatment, researchers conducted a retrospective real-life study taking place between December 2015 and September 2016 and using the medical records of 872 omalizumab-treated patients with SAA.

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The researchers used 3 criteria to assess response to omalizumab: physician evaluation, reduction of ≥40% in annual exacerbation rate and a combination of both. Blood eosinophil count from the year prior to omalizumab initiation was used to calculate response rate.

Overall, blood eosinophil count was ≥300 cells·µL−1 in 52.1% of adults (aged 18 years or older) and 73.8% of minors (aged 6 to 17 years). By physician evaluation, 67.2% of adults and 77.2% of minors were responders and 71.1% adults and 78.5% minors had a ≥40% reduction in the exacerbation rate. In adults, the response rate for combined criteria was 58.4% for blood eosinophils ≥300 cells·µL−1 (n=377) and 58.1%  for blood eosinophils <300 cells·µL−1 (n=346).

“The STELLAIR study results suggest that, conversely to antibodies targeting specifically the eosinophil activation pathway, omalizumab therapy is effective in eligible patients with SAA irrespective of the pre-treatment blood eosinophil count,” the researchers concluded.

—Michael Potts

Reference:

Humbert M, Taille C, Mala L, et al. Omalizumab effectiveness in patients with severe allergic asthma according to blood eosinophil count: the STELLAIR study [published online May 10, 2018] Euro Respir J. doi: 10.1183/13993003.02523-2017