UCSF team submits FDA application for first in utero gene therapy trial
A University of California San Francisco team has applied to the FDA for permission to run a small first-in-human trial of gene therapy delivered before birth for a rare lysosomal storage disorder.
Researchers led by foetal surgeon Tippi MacKenzie at the University of California San Francisco have submitted an Investigational New Drug application to the US Food and Drug Administration seeking approval to begin a small phase I trial of in utero gene therapy. The target condition is a rare lysosomal storage disorder — a category of inherited metabolic diseases caused by deficiencies in enzymes responsible for breaking down cellular waste products.
In utero gene therapy aims to deliver a functional copy of a defective gene to the foetus during pregnancy, before the progressive tissue damage characteristic of lysosomal storage disorders takes hold. The UCSF team's application, reported by STAT News following remarks at the STAT Breakthrough Summit West, represents a significant translational step for a field that has for years sought a regulatory pathway to first-in-human studies.
No peer-reviewed publication describing the full preclinical data package has been identified in this reporting cycle; the primary source is STAT News coverage of MacKenzie's conference remarks. The FDA's review process will determine whether the trial may proceed and under what conditions. If cleared, the study would be among the first in the world to test gene therapy administered in utero in human participants.
Plain-language version
For patients, families, and general readers. Educational only — not medical advice.
Scientists at the University of California San Francisco have asked the US medicines regulator — the Food and Drug Administration (FDA) — for permission to run a very small early trial of a new type of treatment. The treatment would deliver a working copy of a faulty gene to a baby before it is born, with the aim of preventing the harm caused by a rare inherited condition called a lysosomal storage disorder. These are conditions where the body cannot break down certain substances inside cells properly, leading to a build-up that damages tissues over time.
This is still at a very early stage — the regulator has not yet decided whether the trial can go ahead. Researchers say the goal of this kind of study is first to check safety. No results are available yet.
This is an educational summary, not medical advice. If anything here raises questions for you, please speak with your GP or a clinical professional.
Sources
Read the original reporting — these are the public sources this summary draws from.
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Primary source Stat News · 2026-05-20STAT+: Pioneering trial for treating genetic disease before birth nears reality