Project Summary The digital sharing and storage of healthcare information—medical claims and electronic health records—has produced lakes of real-world data (RWD) in the modern health care landscape. This volume of digital data, along with revolutions in big-data analysis, provide a new opportunity to use RWD to produce real-world evidence (RWE). RWD/RWE can improve the regulatory science around the development and review of biosimilar drugs. RWD have the potential to capture information from tens of millions of patients in real- world clinical practice. The use of RWD/RWE to improve the efficiency of clinical trials for biosimilar products will speed the development of new biosimilars, the process of granting the regulatory designation of interchangeability, and encourage more rapid uptake of the products in the market. The lack of evidence on the quality of RWD and on the relevance of RWE for regulatory decision-making about biosimilars is a major obstacle to using big-data analyses of RWD/RWE for these decisions. The study, “Improving the Efficiency of Regulatory Decisions for Biosimilars and Interchangeable Biosimilars by Leveraging Real-World Data to Produce Real-World Evidence,” will provide the research community with analytical tools they can re-use for their own tests of interchangeability and other regulatory questions. In the proposed study, we will: Aim 1: Determine the quality of RWD and the relevance of RWE for regulatory decision- making. We will conduct a literature review and convene an expert panel to establish the data needs for regulatory approvals of new biosimilars and designations of interchangeability. Then we will determine whether and where RWD/RWE could reasonably be used to address regulatory data needs. Aim 2: Use RWD/RWE to emulate an FDA evaluation of interchangeability of a biosimilar drug. We will design and conduct a target trial emulation of a switching study and compare outcomes produced from the emulation to those obtained from the FDA’s evaluations of interchangeability of the reference drug.