A retrospective analysis of factors influencing response to omalizumab treatment in Indian patients with antihistamine refractory chronic spontaneous urticaria.

Background: Chronic spontaneous urticaria (CSU) presents as a persistent and distressing condition, with varying treatment responses. Omalizumab, a monoclonal anti-IgE antibody, has shown efficacy in managing antihistamine (AH₁)-refractory CSU, but its varied response patterns and associated factors remain understudied, particularly in India.

Methods: We conducted a retrospective study involving 81 antihistamine-resistant CSU patients treated with omalizumab at a tertiary care center in Northern India between 2018 and 2023. Baseline characteristics, treatment response, and adverse effects were analyzed. Patients were categorized into various response groups based on treatment timelines and biomarker correlations.

Results: We observed 65% achieved symptom cessation (group 1) following a single omalizumab dose, while 21% responded between second and third doses (group 2). A subset (7.4%) necessitated increased dosing frequency (group 3) for symptom control. Additionally, 6.2% showed persistent symptoms despite increased dosing frequency (group 4), exhibiting distinctive biomarker profiles indicative of an autoimmune endotype. Notably, 27.1% experienced exacerbations during treatment, emphasizing the need for tailored management approaches and response expectations.

Conclusion: Omalizumab demonstrated remarkable efficacy in the treatment of AH₁-refractory CSU, with a good safety profile. This study highlights the complexity of treatment response to omalizumab and the potential utility of biomarkers in guiding personalized therapeutic strategies. Further research into biomarker-based endotypes is warranted to optimize CSU management.