D1.463 - Real-World Transition from Reference Omalizumab to Biosimilar Omlyclo in Patients with Chronic Urticaria: A Single-Center Descriptive Study

Omalizumab has become a cornerstone in the management of chronic urticaria, particularly chronic spontaneous urticaria (CSU). With the introduction of biosimilars such as Omlyclo, real-world data assessing clinical control and patient-reported outcomes after switching from the reference product are essential. This study aims to characterize a cohort of patients transitioned to Omlyclo and evaluate early outcomes in routine clinical practice.

We conducted a retrospective real-world analysis of 86 patients with chronic urticaria, including 84 with chronic spontaneous urticaria (CSU) and 2 with chronic inducible urticaria (CIndU) to date. The transition from reference omalizumab to the biosimilar Omlyclo began in October 2025. All patients had previously been treated with reference omalizumab and were subsequently switched to the biosimilar. Demographic and clinical variables collected included age, sex, baseline total serum IgE, presence of angioedema, duration of anti-IgE therapy, and dosing regimen. Disease control is being assessed using the Urticaria Control Test (UCT). Patient satisfaction and treatment convenience are being evaluated using standardized surveys. We are still analyzing UCT scores obtained after biosimilar initiation to directly compare them with pre-switch UCT data already available in our registry. 

The cohort demonstrated a marked female predominance (71.8%) and encompassed a broad age range. Concomitant angioedema was documented in 44.8% of patients. Baseline total serum IgE levels were highly heterogeneous, ranging from 4.2 to 1857 IU/mL. The majority of patients were receiving omalizumab at a dose of 300 mg (n=51), predominantly administered every 4 weeks.

Preliminary post-switch UCT data indicate sustained disease control, with no significant loss of efficacy observed. Patient-reported satisfaction remained high following the transition. The safety profile was consistent with that of the reference product, with no significant adverse events or cases of anaphylaxis recorded during the follow-up period.

Regarding concomitant therapy, 66.7% of patients required additional anti-H1 antihistamines alongside omalizumab, whereas 33.3% achieved adequate CSU control without the need for any supplementary treatment.

Most patients were long-term responders to anti-IgE therapy, with a substantial proportion having received treatment for more than 12 months before the switch.

This real-world cohort confirms that transitioning from reference omalizumab to biosimilar anti-IgE therapy is safe and maintains clinical disease control in a heterogeneous chronic urticaria population. Early findings further indicate sustained patient-reported treatment satisfaction following the switch. Ongoing longitudinal analyses will provide long-term UCT comparisons to further substantiate these early-phase findings.