For one of the deadliest rare childhood diseases, there is now a curative treatment for the first time. On March 26, 2026, the U.S. Food and Drug Administration approved the gene therapy Kresladi for children with severe leukocyte adhesion deficiency type I (LAD-1). In a Phase 1/2 trial, all nine treated children survived the first twelve months without relapse, and most have since been under long-term observation.
A Disease Almost No One Knows
LAD-1 is a congenital immunodeficiency that affects an estimated one in one million people worldwide. In the United States, approximately 25 new cases are diagnosed each year. The cause is mutations in the ITGB2 gene, which encodes the surface proteins CD18 and CD11a. These proteins allow white blood cells to migrate from the bloodstream into tissue and fight infections. Without them, patients are defenseless against bacterial and fungal infections from birth.
Without treatment, most children with the severe form of the disease do not survive their first decade of life. The previous standard therapy was a stem cell transplant from an HLA-compatible sibling donor, which most patients simply do not have. Kresladi was developed specifically for these children with no suitable donor.
How Kresladi Works
The active substance is formally named Marnetegragene Autotemcel. The procedure is an autologous therapy: hematopoietic stem cells are first extracted from the patient's own bone marrow, then genetically corrected in the laboratory by inserting a functional copy of the ITGB2 gene. The children then receive their corrected cells back as a one-time infusion.
The key advantage over conventional transplantation: because the cells originate from the patient's own body, there is no risk of a severe rejection reaction. Long-term data to date show that the genetic correction persists for at least 36 months. All treated patients showed normal CD18 and CD11a levels in their blood, and chronic skin lesions healed following treatment.
What the Clinical Data Show
The FDA approval is based on an international Phase 1/2 trial. The overall survival rate of all enrolled patients after at least twelve months of follow-up was 100 percent. By comparison, children without a suitable donor who received conventional treatment had a historical survival rate of around 50 percent for the severe form. The FDA granted approval under its Accelerated Approval pathway, reserved for serious conditions with no adequate alternative treatments.
Kresladi was developed by Rocket Pharmaceuticals, a New York-based company specializing in gene therapies. The price of the treatment has not yet been publicly disclosed. Similar gene therapies for rare diseases in the United States typically cost between one and three million dollars per treatment.
A Model for Other Rare Diseases
LAD-1 is only the third primary immunodeficiency after adenosine deaminase deficiency and severe combined immunodeficiency (the so-called bubble baby syndrome) to receive regulatory approval for a gene therapy. Researchers see the approach as a blueprint for other monogenic diseases — conditions caused by a single faulty gene. According to WHO estimates, there are approximately 7,000 such rare diseases worldwide, and for the vast majority no curative treatment exists.
The regulatory framework applied here holds broader implications: when a clear clinical signal is measured in a small patient group and no alternative exists, the FDA's Accelerated Approval pathway allows authorization even with limited data. This principle is now being watched closely by researchers working on dozens of similar rare pediatric conditions.
Outlook
Rocket Pharmaceuticals has announced a registry study to monitor all Kresladi-treated patients over the long term. The European Medicines Agency (EMA) is currently reviewing a marketing authorization application for the European market; no approval date in the EU has been set yet. Which treatment centers will initially offer the drug will depend on Rocket Pharmaceuticals and on which clinics are capable of performing the patient-specific manufacturing process.