Changes in Evidence Used for FDA Novel Drug Approvals Following the Implementation of the 21st Century Cures Act

Background: The 21st Century Cures Act (2017) expanded FDA flexibility in applying methodological standards for drug approval. To examine trends before and after implementation, we independently reviewed all novel drugs approved between 2016 and 2024. Methods: We constructed a database of all novel FDA approvals from January 1, 2016, through December 31, 2024. Each study linked to an approved drug (N=6,763) was cataloged by study number, sponsorship, and timing of results reporting relative to completion. Results: Since 2016, the number of studies supporting approval has steadily declined. Beginning in 2017, the modal number of studies per approval fell to one. Industry sponsorship increased while NIH-supported studies decreased. Average time to public posting of results exceeded the one-year statutory limit. Conclusions: After implementation of the Cures Act, FDA approvals have relied on fewer, increasingly industry-sponsored studies. Although this may accelerate access to new therapies, it raises concerns about the strength of evidence for safety and effectiveness.