top of page

FDA’s finalized “Interpreting Sameness” Gene Therapy Products Guidance

USFDA on 29 September 2021, finalized "Interpreting Sameness of Gene Therapy Products Under the Orphan Drug Regulations". This guidance finalizes the draft guidance of the same title dated January 2020.

This guidance provides FDA’s current thinking on determining the sameness of human gene therapy products under FDA’s orphan drug regulations for the purpose of orphan-drug designation and orphan-drug exclusivity.

This guidance is intended to assist stakeholders, including industry and academic sponsors who seek orphan-drug designation and orphan-drug exclusivity, in the development of gene therapies for rare diseases.

Orphan drug regulations that define when drugs are the “same drug” do not address how that definition would apply to gene therapy products, so FDA drafted the guidance to clarify its stance. The final guidance leaves intact the general framework of the draft, where gene therapies expressing different transgenes are considered different drugs for orphan exclusivity purposes, regardless of which vectors are used.

This guidance focuses specifically on factors that FDA generally intends to consider when determining sameness for gene therapy products and does not address sameness determinations for other types of products.


bottom of page