The FDA expanded guidance for cell and gene therapy developers on how to leverage prior knowledge across clinical, nonclinical and manufacturing work. In a new CBER draft guidance, the agency outlined how sponsors can use “what’s already known” to support development plans rather than repeatedly generating redundant datasets. The FDA’s draft document covers the types of prior information that may be used, including publicly available data and platform-based knowledge, and how that knowledge can be incorporated into submissions. For sponsors, the key operational takeaway is planning: development teams may be able to structure evidence packages more efficiently while still meeting FDA expectations on comparability, manufacturing relevance and analytical rigor. The guidance also signals a broader shift toward evidence reuse and structured justification, a critical theme as sponsors face manufacturing scale constraints and timelines for next-generation gene therapies.