Improving clinical research through better use of clinical trial registry data.

Clinical trials are crucial for evidence generation on medicines. As of June, 2025, the European Union's (EU) clinical trial registries (Clinical Trial Information System and European Clinical Trial Register) housed data on nearly 55 000 clinical trials. The full potential of these data, especially when integrated with other sources such as real-world data, has remained mostly untapped for wider health-care innovation. In this Viewpoint, we report on the outcomes of an exploratory workshop with key stakeholders from across clinical research, held in Jan 25 and 26, 2024 under the Accelerating Clinical Trials in the EU (ACT EU) initiative. The workshop identified needs and potential use cases for the clinical trial registry data by gathering and analysing perspectives from diverse stakeholders. The analysis presented in this Viewpoint groups the use cases into three themes: optimising trial design and planning to leverage historical trial data for research optimisation; enhancing patient centricity to meet the diverse needs of patients; and strengthening the evaluation of evidence to maximise the collective effect of clinical trial data for regulatory, clinical, and policy decision making. Strong consensus emerged on key enablers for better use of data. These enablers were data standardisation to ensure consistent data representation among registries; data quality to enable reliable data analysis and decision making; interoperability to allow digital health systems to communicate seamlessly; and transparency to ensure data are made available to the public. As an initial step in addressing these needs, the European Medicines Agency developed the ACT EU trial map as a patient-oriented platform enabling easy trial discovery. The use cases identified at the workshop provide different starting points for supporting the setup of a clinical trial analytics ecosystem to enhance evidence-based decision making, foster innovation, guide funding, and ultimately benefit public health.