FDA Transparency Reveals Strategic Lessons from Rejection Letters for Kisunla, Vyondys 53, and Sunlenca
SHERIDAN, WYOMING – July 12, 2025 – A landmark release of 200 complete response letters (CRLs) by the U.S. Food and Drug Administration (FDA) has unveiled a decade of regulatory decisions behind once-rejected therapies, now approved and on the market. Among the most revealing cases are Eli Lilly’s Alzheimer’s treatment Kisunla, Sarepta’s Duchenne muscular dystrophy drug Vyondys 53, and Gilead’s long-acting HIV therapy Sunlenca.
This unprecedented act of “radical transparency” by the FDA marks a rare window into the regulatory reasoning typically hidden from public view. Each letter provides detailed insight into the challenges biopharmaceutical companies face—from inadequate safety data to packaging compatibility issues—offering strategic guidance for future drug development and market approval.
Kisunla CRL Highlights FDA’s Long-Term Safety Expectations