The US FDA has granted accelerated approval to Kresladi (marnetegragene autotemcel; RP-L201), an autologous hematopoietic stem cell-based gene therapy developed by Rocket Pharmaceuticals for pediatric patients with severe leukocyte adhesion deficiency-I (LAD-I) caused by biallelic variants in the ITGB2 gene. The approval makes Kresladi the first gene therapy cleared by the FDA for this ultra-rare primary immunodeficiency. The agency also granted Rocket a Rare Pediatric Disease Priority Review Voucher.
LAD-I affects an estimated one in 100,000 to one in 200,000 live births in the US, with roughly two-thirds of cases classified as severe. Without treatment, infants with the severe form face recurrent life-threatening bacterial and fungal infections and high early-childhood mortality. Kresladi is indicated specifically for pediatric patients with severe LAD-I who lack an available human leukocyte antigen (HLA)-matched sibling donor for allogeneic hematopoietic stem cell transplant, the only previously established curative option. The approval was granted under the accelerated approval pathway, based on a surrogate endpoint: increases in neutrophil CD18 and CD11a surface expression following treatment. Continued approval may be contingent on verification of clinical benefit through longer-term follow-up of treated patients in the ongoing clinical study and through a post-marketing registry.
The approval was supported by data from a global Phase I/II study in pediatric patients with severe LAD-I, which enrolled nine children aged five months to nine years across multiple centers. In the trial, all nine treated patients achieved 100% overall survival at 12 months post-infusion and remained alive without requiring hematopoietic stem cell transplant, with follow-up extending up to 18–42 months. Treatment was associated with substantial reductions in severe infections and hospitalizations, alongside resolution of disease-related skin lesions and improved wound healing. Investigators also observed sustained increases in neutrophil CD18 and CD11a expression—biomarkers directly linked to the underlying ITGB2 defect and used as the surrogate endpoint supporting accelerated approval. The therapy was generally well tolerated, with no treatment-related serious adverse events reported in the study. Results were published to Clinical Immunology.
For the small population of children with severe LAD-I, the approval addresses a defined gap. Allogeneic hematopoietic stem cell transplant from an HLA-matched sibling donor has been the standard curative approach, but most patients lack such a donor. Without transplant, management has been limited to antimicrobial prophylaxis and treatment of acute infections, neither of which corrects the underlying immune defect.
The development landscape for LAD-I remains limited, reflecting the disease’s rarity. Beyond Kresladi, clinical-stage activity is sparse, with few publicly disclosed gene therapy programs targeting ITGB2 and no other advanced assets with regulatory validation. Academic research continues to explore gene-editing approaches, including CRISPR/Cas9 and base editing strategies aimed at correcting ITGB2 mutations, though these remain at preclinical or early investigational stages. Alternative transplant approaches, such as haploidentical hematopoietic stem cell transplant, are also being evaluated for patients without matched sibling donors. The accelerated approval of Kresladi establishes a regulatory benchmark in this setting, with long-term follow-up required to assess durability and monitor risks associated with lentiviral vector–mediated insertional oncogenesis.
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