Use of real-world evidence in regulatory decisions for rare diseases in the United States-Current status and future directions.

Following the release of the framework for the Real-World Evidence (RWE) Program, the US Food and Drug Administration (FDA) is actively evaluating and exploring ways to optimize the utility of real-world data (RWD) and RWE to support regulatory decision making. For rare conditions, conducting traditional randomized clinical trials may not always be feasible, and RWD and RWE have played and will continue to play an important role. We use three case examples-cerliponase alfa, asfotase alfa, and uridine triacetate-to illustrate how RWD from disease registries, medical records with chart review, and literature, respectively, have been used to generate RWE to support regulatory decisions for selected rare diseases. These examples highlight the need for improving data reliability and quality in existing data to expand use of RWD and RWE beyond "hard endpoints" and standardizing data collection for outcome measures in patient registries to expand its utility. We also discuss a recent FDA guidance for using RWE in supporting rare disease drug development, including its recommendations about using natural history studies as external control groups for single-arm interventional trials. The external control group needs to be comparable with the treated group. Selection bias and confounding are major concerns because of lack of randomization and unrecognized baseline differences. Use of valid epidemiological approaches can reduce these biases. Lastly, we discuss future directions to expand the use of RWD and RWE to support orphan drug approvals, including the need for including patient experience data as an important source of RWD.