FDA Finalizes Cell and Gene Therapy Development Guidance, with 36 Q&As Mapping the Path from IND to Marketing Application

The challenges of cell and gene therapies lie not only in whether cells can be engineered or genes delivered, but also in the fact that every manufacturing process change, analytical method, and clinical endpoint may affect whether a product is still considered safe and consistent. The U.S. Food and Drug Administration (FDA) has now finalized industry guidance covering 36 questions and answers, seeking to organize the recurring issues faced by developers into a clearer regulatory pathway.

The final guidance, issued in August 2026, spans five core areas: regulatory submissions and review, chemistry, manufacturing, and controls (CMC), pharmacology and toxicology, clinical development, and clinical pharmacology. It covers topics ranging from electronic submission of investigational new drug applications (INDs) and the respective roles of INTERACT and pre-IND meetings to donor eligibility, product characterization, critical quality attributes, comparability following manufacturing process changes, and premarketing preparations.

One practical focus is to explain more specifically what questions to ask the FDA and when. INTERACT meetings are appropriate when a product has begun to take shape and has early proof of concept, but pivotal toxicology studies have not yet begun. Pre-IND meetings are used to discuss the nonclinical study designs, manufacturing and quality controls needed to support human trials, as well as the first clinical study. For resource-constrained academic teams or startups, choosing the right point for communication may reduce the risk of having to repeat studies or supplement manufacturing data.

The guidance also addresses evidence challenges specific to cell and gene therapies. If no suitable animal model of the disease is available, developers may submit in vitro data, computer simulations, analogous animal product data, or relevant clinical data, but must still explain how the evidence collectively supports human trials. On the manufacturing side, developers must distinguish product characterization from release testing and progressively establish critical quality attributes, the suitability of analytical methods, and comparability evidence from before and after manufacturing process changes.

This work stems from the FDA’s commitment under PDUFA VII to improve the efficiency of cell and gene therapy development. The FDA compiled questions from industry consultations, public events, and the Office of Therapeutic Products, released draft guidance in 2024, and finalized it after a public comment period. At the time, the American Society of Gene & Cell Therapy welcomed the draft as an introductory roadmap, but also noted that it offered experienced developers limited guidance when confronting complex characterization, acceptance criteria, and comparability studies.

The final guidance is therefore more like a common base map than a formula that every product can follow to secure approval. The FDA explicitly states that the guidance presents its current recommendations, is generally not legally enforceable, and allows alternative approaches as long as they comply with applicable regulations; the agency may also add questions and answers in the future. For highly individualized therapies, those intended for limited patient populations, or those with rapidly evolving manufacturing processes, questions such as how quality attributes relate to clinical outcomes, whether surrogate endpoints can predict benefit, and the extent of long-term safety monitoring will still need to be negotiated on a product-by-product basis.