Subgroup Analysis Identifies Differences Between Sexes In How CIU Patients Respond To Omalizumab
Saturday, March 3, 2018
South Hall A2 (Convention Center)
Sarbjit Singh Saini, MD FAAAAI, Benjamin L. Trzaskoma, MS, Noelle M. Griffin, PhD
RATIONALE: It has previously been shown that whole blood histamine concentration and circulating basophils increase in response to omalizumab, which parallel improvements in disease symptoms. It is not known whether patient characteristics can differentially influence these changes.

METHODS: Post-hoc analysis of GLACIAL Phase 3 CIU study to examine treatment with omalizumab in subgroups defined by patient demographics (age, duration of CIU, previous CIU medication, baseline UAS7, sex, race, presence of angioedema, CU index status) with respect to the change from baseline to end of study in whole blood histamine (n=404) or percentage circulating basophils (n=426) (%basophils). Analyses were also conducted to assess whether patient demographics that showed differential treatment effects when modeling histamine or basophil outcomes, exhibited similar differentiation when modeling change from baseline in UAS7 scores.

RESULTS: Of all subgroups explored, only differences between sexes were consistently statistically significant when modeling both blood histamines and %basophils. At the end of 24 weeks of treatment, males showed greater treatment-related increases versus females in whole blood histamine (ng/mL)(mean 7.30 vs 1.86, p<0.001), and in %basophils (20.8% vs 8.9%, p=0.05).

These differences between the sexes were not observed with time to response or overall response rate as similar improvements in UAS7 score were observed (mean -9.52 vs -7.26, p=0.36) and similar time to responses were also noted between males and females.

CONCLUSIONS: These data suggest that while the overall response to omalizumab (based on UAS7 score) is similar between males and females, analyses of whole blood histamines and %basophils indicate differences between sexes during omalizumab treatment.