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Draft Level 1 Guidance

Not for implementation. Contains non-binding recommendations.

This guidance is being distributed for comment purposes only.

Submit Comments Online

Although you can comment on any guidance at any time (see 21 CFR 10.115(g)(5)), to ensure that the FDA considers your comment on a draft guidance before it begins work on the final version of the guidance, submit either online or written comments on the draft guidance before the close date.

If unable to submit comments online, please mail written comments to:

Dockets Management
Food and Drug Administration
5630 Fishers Lane, Rm 1061
Rockville, MD 20852

All written comments should be identified with this document's docket number: FDA-2021-D-0875

Docket Number:


Issued by:
Guidance Issuing Office
Center for Drug Evaluation and Research
Center for Biologics Evaluation and Research

The objective of this guideline is to provide harmonised recommendations for the conduct of nonclinical biodistribution (BD) studies in the development of gene therapy (GT) products. This document provides recommendations for the overall design of nonclinical BD assessments. Considerations for interpretation and application of the BD data to support a nonclinical development programme and the design of clinical trials are also provided. The recommendations in this guideline endeavour to facilitate the development of GT products while avoiding unnecessary use of animals, in accordance with the 3Rs (reduce/refine/replace) principles.

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