HOUSTON — In a post hoc analysis of the PROSPERO clinical trial (ClinicalTrials.gov Identifier: NCT01922037), response to omalizumab was similar regardless of the number and type of sensitizing allergens in patients with allergic asthma, according to data presented at the American College of Allergy, Asthma, & Immunology Annual Scientific Meeting held November 7-11, 2019, in Houston, Texas.

Researchers identified 478 patients from the original trial who had specific immunoglobulin E data for 13 tested allergens for this post hoc analysis. Because omalizumab reduces asthma exacerbations in moderate to severe allergic asthma, the researchers wanted to learn whether there could be an association between the number or type of allergens (seasonal or perennial) and treatment response. They used a Poisson regression model to estimate protocol-defined exacerbation rates normalized by omalizumab treatment duration, age, number of allergens (nonsensitized, monosensitized, paucisensitized, or polysensitized), or type of allergens.

The exacerbation history was substantial in all of the patient subgroups, with approximately 3 mean exacerbations in the previous year. After omalizumab initiation, the adjusted exacerbation rates ranged from 0.56 to 0.85, regardless of the number and type of allergen sensitization. Monosensitized patients had the lowest number of exacerbations, which tended to increase by the number of allergens, but nonsensitized patients had the highest exacerbation rates. Patients with perennial allergies had the lowest exacerbation rates compared with those with seasonal or both allergy types.

This analysis had several limitations including the post hoc nature, small sample sizes in some subgroups, and the lack of a placebo group.

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“After omalizumab initiation, we observed low and similar exacerbation rates across subgroups with heterogeneous allergen sensitization profiles, but 95% CIs highly overlapped between subgroups,” the researchers noted.

Reference

Soong W, Yoo B, Pazwash H, Holweg C, Casale T. Response to omalizumab in allergic asthma patients by number and type of allergens in PROSPERO. Presented at: American College of Allergy, Asthma, & Immunology Annual Scientific Meeting 2019; November 7-11, 2019; Houston, TX. Abstract P208.