Retrospective Evaluation of Omalizumab Treatment Efficacy in Patients with Bullous Pemphigoid

<b>Background/Objectives</b>: Bullous pemphigoid (BP) is a manageable condition, and the primary goal of treatment is to control the disease while minimizing the use of corticosteroids due to their potential side effects with long-term use. The primary aim of this study was to assess the effectiveness of omalizumab (OMZ) treatment in bullous pemphigoid patients using both objective and subjective indicators, including bullous pemphigoid disease area index (BPDAI) score, peripheral eosinophil count, serum total IgE level, systemic corticosteroid dosage, and pruritus severity (VAS pruritus). The secondary aim was to explore potential predictors of treatment response, such as baseline BPDAI, age, gender, lesion distribution, serum total IgE, peripheral eosinophil count, maximum and minimum corticosteroid dose, and comorbidities, as well as to evaluate the time to clinical response and corticosteroid tapering. <b>Methods</b>: This retrospective analysis included 25 BP patients treated with OMZ as add-on therapy to systemic corticosteroids between January 2023 and December 2024 at Health Sciences University, Başakşehir Çam and Sakura Training and Research Hospital, Dermatology and Venerology Clinic. No other systemic immunosuppressants were permitted. All patients were already receiving systemic corticosteroids at enrolment. This retrospective analysis included 25 BP patients receiving omalizumab (300 mg/4 weeks) as an add-on to systemic corticosteroids, initiated primarily for steroid-refractory disease and/or persistent, sleep-disrupting pruritus. Baseline was defined immediately before the first OMZ dose; assessments were performed at baseline and week 12. Clinical (BPDAI, VAS pruritus) and laboratory (eosinophil count, total IgE levels) parameters were assessed at baseline and week 12. <b>Results:</b> OMZ treatment significantly reduced disease severity, as evidenced by a mean decrease in the BPDAI score of 105.0 ± 48.9 (95% CI 84.8-125.2) compared to baseline (<i>p</i> < 0.001). Peripheral eosinophil count also decreased by 0.6 ± 0.3 (95% CI 0.4-0.7) after treatment (<i>p</i> < 0.001). Total serum IgE levels declined significantly in 92% of patients (95% CI 244.5-2171.3) compared to pretreatment (<i>p</i> < 0.001), although two patients (8%) showed an increase (202.0 ± 258.8) after OMZ treatment. OMZ treatment led to a mean systemic corticosteroid dose reduction of 37.0 ± 14.1 mg (95% CI 31.1-42.8 mg), with a median corticosteroid tapering time of 4 weeks (3.0-4.0). Additionally, pruritus severity, measured by pruritus VAS, decreased by 6.2 ± 1.4 (95% CI 5.6-6.7) following treatment (<i>p</i> < 0.001). OMZ was well tolerated, with no serious adverse events. <b>Conclusions</b>: Within a 12-week observation window, we observed improvements in disease activity and pruritus alongside reduced corticosteroid exposure. Given the retrospective, uncontrolled add-on design, these findings do not establish causality but support further prospective controlled evaluation of omalizumab as a steroid-sparing option. Importantly, OMZ treatment significantly reduced the mean corticosteroid dose, pruritus VAS score, total IgE levels, and eosinophil count, indicating therapeutic activity and supporting its use as an effective steroid-sparing option in the management of bullous pemphigoid.