Budget impact of introducing an omalizumab biosimilar in 23 European countries

Omalizumab, a monoclonal antibody indicated for severe persistent allergic asthma, chronic spontaneous urticaria (CSU), and chronic rhinosinusitis with nasal polyps (CRSwNP), imposes a financial burden on European healthcare systems due to its high cost, with expenditures exceeding €787 million across 23 countries in 2024. Introducing an omalizumab biosimilar offers a promising avenue to reduce expenditure while maintaining clinical outcomes. To evaluate the budgetary impact of introducing an omalizumab biosimilar for severe persistent allergic asthma, CSU, and CRSwNP across 23 European countries from a payer’s perspective. A biosimilar market share uptake-based budget impact model (BIM) was developed in Microsoft Excel to compare two scenarios over 5 years: one without biosimilar introduction and one with gradual adoption. Market share evolution was modeled using country-specific biosimilar uptake as a proxy, while omalizumab usage growth was estimated from historical compound annual growth rates. Drug acquisition costs came from national price databases, assuming a 30% discount for the biosimilar. Sensitivity analysis applying 50% and 70% discount rates was conducted to reflect reimbursed cost from the payer’s perspective. Introducing an omalizumab biosimilar is projected to save €40 million in the first year at a 30% discounted price compared with using only the originator across 23 countries. Over 5 years, cumulative savings could reach €640 million, potentially enabling treatment for ∼96,000 additional patients from the derived budget savings. These estimates are a conservative baseline because the model does not incorporate competitive price erosion of the originator following biosimilar entry; in real-world settings, savings are typically higher when originator prices decline in response to competition. Adopting an omalizumab biosimilar in European healthcare systems could yield substantial cost savings, enhance patient access, and reduce fiscal pressure. This analysis supports biosimilars as a strategic tool for sustainable biologic therapy access in Europe.