FDA Approves Gene Therapy for Rare Immune Disorder

Therapy developed by UCLA researcher could provide blueprint for other rare disease treatments

Mar. 28, 2026 at 12:58am

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The FDA has approved a gene therapy developed by UCLA researcher Dr. Donald Kohn for the treatment of severe leukocyte adhesion deficiency-I, a rare genetic condition that leaves children susceptible to life-threatening infections. The therapy, which adds a healthy copy of the ITGB2 gene to patients' own blood stem cells, has shown sustained efficacy and safety in a clinical trial, enabling patients to produce functional immune cells and fight infections more effectively.

Why it matters

Severe leukocyte adhesion deficiency-I is an extremely rare condition that affects only about one in a million children globally. Without treatment, survival beyond childhood is rare. This FDA approval marks a major milestone, as it provides a potential blueprint for developing and commercializing therapies for other rare diseases that currently lack effective treatments.

The details

The gene therapy, marketed under the name Kresladi, was developed by Rocket Pharmaceuticals and tested in a clinical trial led by Dr. Kohn at UCLA. The trial enrolled nine patients aged 5 months to 9 years, with six treated at UCLA and three in London and Spain. The therapy works by adding a healthy copy of the ITGB2 gene to each child's blood stem cells, enabling their bodies to produce functional immune cells to fight infections. All nine patients survived without needing a bone marrow transplant, and data showed a significant reduction in severe infections requiring hospitalization.

  • The clinical trial results were published in the New England Journal of Medicine in April 2025.
  • The FDA approved the gene therapy in March 2026 under the accelerated approval pathway.

The players

Dr. Donald Kohn

A distinguished professor of microbiology, immunology and molecular genetics at UCLA who has been developing gene therapies for rare pediatric immune disorders for over 30 years. He led the clinical trial that led to the FDA approval of the gene therapy for severe leukocyte adhesion deficiency-I.

Rocket Pharmaceuticals

The company that sponsored the clinical trial and developed the gene therapy, Kresladi, which has now been approved by the FDA.

California Institute for Regenerative Medicine (CIRM)

A California state agency that co-funded the clinical trials for the gene therapy in collaboration with Rocket Pharmaceuticals.

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What they’re saying

“I saw a marked improvement across all patients in terms of restored immune function. Seeing these patients annually for their follow-up visits and witnessing that they no longer battle life-threatening infections has been incredibly meaningful.”

— Dr. Donald Kohn, Distinguished Professor, UCLA

“Hopefully, an approval like this one will encourage other companies to invest in these kinds of therapies and recognize that there is a pathway to make these commercially available. We've reached a point where it's not the science that's limiting more of these therapies from becoming available, but rather commercial investment. This could help turn that tide.”

— Dr. Donald Kohn, Distinguished Professor, UCLA

What’s next

Confirmation of the clinical benefit of the gene therapy will be based on the evaluation of longer-term follow-up data of treated patients in the clinical study and through a post-marketing registry.

The takeaway

This FDA approval of a gene therapy for a rare, life-threatening immune disorder represents a significant milestone in the field of regenerative medicine. It demonstrates the potential for these types of personalized treatments to transform the lives of patients with rare genetic diseases and could pave the way for more therapies targeting other underserved conditions.