Baseline levels of IgE may serve as a predictor of response to omalizumab in patients with chronic spontaneous urticaria (CSU), according to findings published in The Journal of Allergy and Clinical Immunology.

The researchers enrolled patients diagnosed with CSU. Patients received omalizumab 300 mg for 4 weeks over three cycles, for a total of 12 weeks. At weeks 0, 1, and 12, the study team utilized the urticaria activity score over 7 days (UAS7) to examine clinical symptoms. They also compared clinical characteristics between the response group and the non-response group.

Baseline IgE Levels Higher in Omalizumab Responders

In total, the study included 78 patients with CSU. Most patients (80.8%) responded to treatment with omalizumab, including a complete response in 51.3% of participants and a partial late response in 29.5% of participants. A smaller percentage of the study population—19.2%—had no response to treatment.

The baseline total IgE level among responders was significantly higher than the level among non-responders (127kUA/L vs 41.95 kUA/L; P=0.006). The area under the receiver operating characteristic curve for the total IgE level to predict the efficacy of omalizumab was 0.741 (95% CI, 0.564-0.917; P=0.006). The best cut-off value of total IgE was 56.1 kUA/L, with a sensitivity of 84.2% and a specificity of 71.4%. The positive rate of anti-nuclear antibody (ANA) in the non-responders group was significantly higher than in the responders group (5.13% vs 37.5%; P=0.029).

“Elevated baseline total IgE level (>56.1 kUA/L) indicates better efficacy of omalizumab,” the researchers wrote. “[Patients with CSU] with positive ANA show poor response to omalizumab treatment.”

The study results are also scheduled for presentation at the 2023 Annual Meeting of the American Academy of Allergy, Asthma & Immunology.