The FDA issued additional draft guidance describing how cell and gene therapy developers can use prior knowledge—covering clinical, nonclinical, and manufacturing contexts—to support future regulatory submissions. The guidance is framed as “types of prior knowledge” sponsors can leverage, building on the concept that developers do not always need to start from scratch when platform or publicly available evidence exists. For developers, it affects how clinical protocols, bridging strategies, and manufacturing comparability plans may be constructed. The move signals continued FDA emphasis on scientific justification for cross-study learnings in an area where manufacturing variability and limited patient populations complicate standard evidence packages.