Kresladi Wins FDA Accelerated Approval, Bringing First Gene Therapy to Rare Immunodeficiency

For the small number of children with severe leukocyte adhesion deficiency type I (LAD-I), infection is not an occasional risk but a threat that repeatedly closes in from early life. On March 26, the U.S. Food and Drug Administration (FDA) granted accelerated approval to Kresladi, making it the first gene therapy in the United States for severe LAD-I and opening a new treatment path for children who lack a suitable bone marrow transplant option.

Kresladi’s generic name is marnetegragene autotemcel, and it was developed by Rocket Pharmaceuticals. The FDA product page shows that its indication is limited to pediatric patients with severe LAD-I who have biallelic ITGB2 variants and do not have an available HLA-matched sibling donor for allogeneic hematopoietic stem cell transplantation. This restriction matters: it is not a general immune-boosting therapy, but one aimed at a group of patients with an extremely rare, severe disease course and limited treatment options.

The core problem in LAD-I is an abnormality in the ITGB2 gene, which impairs the function of adhesion molecules on the surface of white blood cells, making it difficult for white blood cells to move effectively to sites of infection and inflammation. The FDA notes that severely affected patients may experience repeated life-threatening bacterial and fungal infections and face a high risk of death in early childhood. Allogeneic hematopoietic stem cell transplantation may be considered, but if there is no HLA-matched sibling donor, transplant-related risks and uncertainty rise substantially.

Kresladi uses a patient’s own hematopoietic stem cells. After CD34-positive cells are obtained through mobilization and apheresis, a functional ITGB2 gene is introduced outside the body, and the cells are then infused back after myeloablative conditioning. The minimum recommended dose listed in the DailyMed label is 2.8×10^6 CD34-positive cells per kilogram of body weight, as a one-time intravenous infusion; this also means the treatment is not a simple injection, but a highly specialized process involving cell collection, manufacturing, conditioning, and infusion.

This approval used the accelerated approval pathway and was based not on fully proven improvement in long-term survival, but on increased expression of CD18 and CD11a on the neutrophil surface. The FDA said these disease-related biomarkers rose 12 months after treatment and were maintained at 24 months, and are reasonably likely to predict clinical benefit. Label data show that the safety data came from a single-arm, open-label clinical study with a limited number of treated pediatric patients; in rare diseases, this type of data structure is common, but it also makes subsequent verification especially important.

The limitations are also clearly stated in regulatory documents. Kresladi’s continued approval may depend on whether confirmatory studies can verify and describe clinical benefit; the FDA approval letter mentioned the review-related clinical trial NCT03812263 and required postmarketing analyses of overall survival, allogeneic transplant-free survival, infection outcomes, and biomarker changes, with the final study report scheduled to be submitted by June 30, 2034. In other words, this approval first moves treatment accessibility one step forward, but whether it can truly rewrite the course of the disease still has to be answered by years of follow-up.

The safety considerations also go beyond general infusion reactions. The DailyMed label lists severe infection, hepatic veno-occlusive disease, neutrophil engraftment failure, delayed platelet engraftment, the risk of lentiviral vector-mediated insertional oncogenesis, hypersensitivity reactions, and the risk of false-positive HIV PCR test results. For gene therapy, efficacy, manufacturing stability, long-term safety monitoring, and real-world accessibility will together determine how far the significance of this rare pediatric therapy can reach.