Exploratory analyses of predictors and correlates of response to omalizumab therapy in patients with multiple food allergies

Background: Stage 1 of the Omalizumab as Monotherapy and as Adjunct Therapy to Multi-Allergen OIT in Food Allergic Children and Adults (OUtMATCH) study demonstrated that treatment with omalizumab for 16 to 20 weeks significantly increased the reaction threshold for peanut and other common food allergens in participants with multiple food allergies. However, the degree of this protection is variable across participants, and there are no known markers to predict or assess individual response to omalizumab. Objective: Our aim was to evaluate clinical and laboratory-based variables as predictors or correlates of response to omalizumab treatment. Methods: Cumulative tolerated dose (CTD) as a continuous variable and thresholds of 444 mg and 1044 mg of individual food proteins were selected as definitions of positive treatment response. Clinical and immunologic variables were evaluated as predictors of response. Results: Omalizumab treatment reduced the level of free IgE. In this exploratory analysis (N = 116), although not definitive, higher total IgE level at baseline was the most consistent predictor of a positive response to omalizumab treatment (peanut CTD: r = 0.25; q = 0.047). Omalizumab dosing frequency (every 2 weeks) was also associated with higher peanut CTD outcomes (r = 0.25; q = 0.047). Medical history of allergy, level of allergen-specific IgE, skin prick test result, and basophil activation did not consistently correlate with response to omalizumab treatment. Concomitant peanut and milk allergy was positively correlated with outcomes of omalizumab treatment (r = 0.34; q = 0.003), whereas peanut allergy concomitant with either cashew allergy (r = -0.43; q = 0.003) or walnut allergy (r = –0.26; q = 0.042) was inversely correlated with outcomes of omalizumab treatment. Conclusion: Of the food allergy biomarkers and omalizumab dosing assessed in this analysis, a higher baseline total IgE level was the most consistent, albeit modest, predictor of successful peanut threshold protection with omalizumab treatment, thus warranting further study.