Tissue Eosinophil Counts: A Promising Marker for Optimizing Omalizumab Treatment in Bullous Pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune blistering disease, predominantly affecting the elderly. Current treatments rely mainly on corticosteroids and immunosuppressive agents but are often limited by significant side effects. Omalizumab, an anti-IgE monoclonal antibody, has emerged as a promising off-label therapy for BP, but predictive markers for treatment response remain poorly understood. This study evaluates the efficacy and safety of omalizumab in BP and explores potential predictors of response, with a focus on tissue eosinophil counts. A retrospective analysis of 27 patients with severe BP treated with omalizumab was conducted. Complete remission (CR) was achieved in 63% of patients, partial remission (PR) in 18.5%, and no response/flare-up in 18.5%. The median total number of omalizumab doses was six (range 6-12), and 70.4% of patients received biweekly dosing. Notably, responders had significantly higher median tissue eosinophil counts (p = 0.040) than non-responders. No significant correlation was observed between treatment response and variables such as age, gender, disease duration, or blood eosinophil counts. Our findings suggest that tissue eosinophil levels may serve as a reliable predictor of omalizumab response in BP (Z = -2.034, p = 0.040). Omalizumab demonstrated significant efficacy with minimal adverse effects, as only one patient reported a mild side effect (tickling sensation in the throat). While the study's single-center design and small sample size limit generalizability, it provides valuable insights into potential predictive markers and supports omalizumab as a safe and effective treatment option for BP.