EU-OPEN: A novel approach for generating European oncology real-world evidence at scale.

11161 Background: The European Oncology Platform for Evidence Needs (EU-OPEN) is a strategic initiative to generate high-quality oncology real-world evidence (RWE) in Europe. It focuses on establishing multi-study partnerships with access to clinically rich data, regional medical expertise and to enable adoption of novel approaches to conduct research on cohorts of interest efficiently at scale. Methods: For each tumor area (e.g., EU-OPEN Breast) , master protocols aligned to specific patient populations (e.g., ER+/HER2- earlier stage breast cancer or triple negative metastatic breast cancer) are developed alongside a fit-for-purpose data assessment at prospective data partners (primarily hospital sites and registries). Data partners are selected based on their data availability, data quality and operational aspects of collaboration. After finalizing the master protocol, supporting documentation (including common data models and statistical analysis plans) are prepared and shared with partner sites for consistent execution. Data partners then curate, harmonize and analyze data in accordance with the study requirements. Studies and patient cohorts can be efficiently refreshed to capture longer-term outcomes. Results: The initiative began in 2024 with a multi-tumor assessment of prospective data partners and an early breast cancer pilot study (completed and published in 2025). EU-OPEN has since expanded to metastatic breast, endometrial, ovarian and esophageal cancers. Collectively these studies encompass 11 cohorts and plan to include > 2,200 patients. Future plans include expanding to additional tumor areas and data partner types, adopting advanced capabilities such as natural language processing (NLP) to maintain ‘live cohorts’ for rapid analyses, and strengthening governance through clinical and data committees across partners. Conclusions: EU-OPEN demonstrates a scalable, efficient approach to generating research-grade European Oncology RWE at scale. As the initiative grows, adoption of novel technologies and deeper collaboration with data and clinical experts will further accelerate insight generation.