The FDA’s Center for Biologics Evaluation and Research (CBER) published draft guidance describing how cell and gene therapy developers can leverage prior knowledge across clinical, nonclinical, and manufacturing work. The draft is designed to help sponsors document what is already known—publicly available or platform-derived—to reduce redundant study generation. The agency’s emphasis is on establishing a structured basis for using existing evidence when planning new programs, potentially affecting everything from study design justifications to manufacturing risk assessments. For developers, it can translate into clearer expectations for what counts as relevant prior knowledge and how it should be reflected in dossiers. The guidance arrives as the field continues to push for faster development cycles while maintaining safety and manufacturing quality for complex modalities, including AAV- and other vector-based therapies.