The US FDA has released a draft guidance aimed at standardizing how developers assess the safety of human gene therapies that use genome editing technologies—an effort officials say could speed up the arrival of treatments for rare and previously untreatable genetic diseases.

 

When finalized, the guidance will set out recommended methods for evaluating safety in a more consistent, science-based way, particularly focusing on risks linked to unintended genetic changes.

 

“Genome editing holds extraordinary promise for treating previously incurable genetic diseases, and today’s announcement represents the FDA's forward approach to drive innovation and advance the development of genome editing therapies,” said FDA Commissioner Marty Makary. 

 

“This guidance provides sponsors with clear, scientifically-grounded recommendations for evaluating off-target editing risks using state-of-the-art sequencing technologies. We are serious about moving this ball forward.”

 

Issued by the Center for Biologics Evaluation and Research, the draft is part of a broader FDA initiative launched in February to accelerate development of individualized therapies for ultra-rare diseases, which the agency says is reshaping how it works with industry on transformative treatments.

 

The document—titled “Safety Assessment of Genome Editing in Human Gene Therapy Products Using Next-Generation Sequencing”—lays out detailed recommendations on sequencing approaches, sample selection, analysis methods, and reporting standards. It builds on earlier 2024 guidance and focuses on the use of next-generation sequencing (NGS) to detect off-target edits and assess genome stability.

 

The recommendations apply across both ex vivo therapies, where cells are modified outside the body before being returned to the patient, and in vivo approaches, where editing occurs directly inside the body. They are intended to support data submitted in early-stage Investigational New Drug (IND) applications as well as Biologics License Applications (BLAs).

 

“Next-generation sequencing not only detects off-target editing and assesses chromosomal integrity; it also requires science-based recommendations for its use. 

 

"We're giving sponsors a roadmap for comprehensive safety assessment while supporting the efficient development of these promising therapies,” said Chief Medical and Scientific Officer and Center for Biologics Evaluation and Research Director Vinay Prasad. 

 

“Our goal is to work collaboratively with the scientific community to bring safe and effective genome editing therapies to patients who need them most," he added.

 

The agency is also urging developers to engage early in the regulatory process—well before formal IND submissions—through programs such as INTERACT meetings and pre-IND consultations to help shape development strategies.