Exploring market dynamics of biological including biosimilar treatments for retinal diseases in Europe: An interrupted time-series analysis.

PURPOSE: To assess the impact of biosimilar ranibizumab and on-patent faricimab market entry on pricing and utilization trends and describe national variation in off-label bevacizumab use in Europe. METHODS: Interrupted time series analysis of quarterly sales data (Q1 2018-Q2 2024) in 11 European countries evaluated ranibizumab utilization and price after biosimilar entry and aflibercept utilization after faricimab entry. A cross-country survey assessed off-label bevacizumab use. RESULTS: Ranibizumab utilization declined in seven of 11 countries (-1.0% to -29.8%) despite biosimilar entry and associated price reductions. Significant negative trend changes in ranibizumab utilization were observed in France (-0.449; p < 0.001), Germany (-3.935; p = 0.021) and Spain (-8.648; p = 0.002), while Hungary (+33.7; p < 0.001) and the UK (+3.4; p = 0.005) showed increases. Negative trend changes in ranibizumab's weighted average price per TD were observed in four countries ranging from € -0.083 (p < 0.001) in Germany to € -1.309 (p < 0.001) in Hungary. Aflibercept utilization increased across all countries during the study period (+23.6% to +243.3%), but subsequent to faricimab entry, downward utilization trends were observed in several countries, indicating a shift in market dynamics potentially due to extended dosing intervals. Survey results revealed substantial heterogeneity in off-label bevacizumab use, reimbursement status, liability attribution and compounding practises, underscoring fragmented policy environments that influence treatment access. CONCLUSION: The study found substantial cross-country variation in anti-VEGF utilization in Europe. Coordinated policy action is needed to support a sustainable biosimilar uptake in this evolving market.