The FDA is Defining Genome Editing Safety

Over the past several weeks, we've discussed how advances in gene delivery are impacting CMC. Our highlighted topics, ranging from mRNA and lipid nanoparticles to in-vivo CAR-T therapies, consistently center around analytical characterization, comparability, and manufacturing readiness. Today, we want to shine that same light on genome editing.

This spring,  the FDA released draft guidance on the safety assessment of genome editing products using next-generation sequencing (NGS). Applying to ex-vivo and in-vivo gene editing approaches, the recommendations affect virtually every genome editing program entering clinical development, including CRISPR-engineered cell therapies, TALENs, in-vivo gene editing delivered by viral vectors or lipid nanoparticles, and newer editing platforms such as base editing. 

In this guidance, the FDA asserts the expectation that sponsors establish a scientifically justified NGS (next-gen sequencing) strategy early, i.e., before entering the clinic. The guidance outlines recommendations for evaluating off-target editing, chromosomal alterations, genomic integrity, sequencing strategies, and the information expected in IND and BLA submissions. More technically, the FDA emphasizes that sequencing should be fit for purpose rather than relying on a single universal assay. This means that sequencing approaches must be selected according to the specific editing platform and clinical context rather than applying a single analytical strategy across all products. Lastly, the guidance also recognizes bioinformatics as an essential component of genome editing safety assessment, placing expectations on data processing, variant calling, and interpretation alongside laboratory testing.

As gene therapies move into the clinic, regulators expect sponsors to characterize editing outcomes with greater depth and scientific rigor, for the safety of patients. All aforementioned studies directly influence downstream process and manufacturing development, comparability planning, and regulatory submissions, and thus, the FDA but also our own CMC experts consistently recommend that these studies be completed early enough to support original IND submissions rather than being added later in development.

At Pharmefex, we keep highlighting this, and we see this as a continuation of the broader evolution across advanced therapies. Our team supports developers of viral vectors, lipid nanoparticles, cell and gene therapies, and genome editing products by integrating CMC strategy, analytical development, and regulatory planning from the earliest stages.  

In summary, the FDA provides a framework for demonstrating product safety and genomic integrity. However, it is programs that utilize Pharmefex’ CMC support to build sequencing strategy, off-target assessment, and genomic integrity from the outset and implement it into their CMC strategy early, that will be better prepared for regulatory review and clinical progression.

#Pharmefex #CMC #NGS #safety #genomeediting #DahliaConsulting #CGT #genetherapy

Sources

FDA Draft Guidance: Safety Assessment of Genome Editing in Human Gene Therapy Products Using Next-Generation Sequencing (FDA-2026-D-1255, April 14, 2026)https://www.fda.gov/regulatory-information/search-fda-guidance-documents/safety-assessment-genome-editing-human-gene-therapy-products-using-next-generation-sequencing

Federal Register Notice (Comment deadline: July 14, 2026)https://www.federalregister.gov/documents/2026/04/15/2026-07285/safety-assessment-of-genome-editing-in-human-gene-therapy-products-using-next-generation-sequencing

Regulatory Affairs Professionals Society (RAPS): FDA Draft Guidance on NGS for Genome Editing Safety AssessmentFDA drafts guidance on using next-generation sequencing to assess gene therapy safety | RAPS