The U.S. Food and Drug Administration approved Waskyra, known by its generic name etuvetidigene autotemcel, as the first cell-based gene therapy for Wiskott-Aldrich syndrome on December 9, 2025, according to an announcement from the agency. The treatment is indicated for pediatric patients aged six months and older and adults who carry a mutation in the WAS gene, provided allogeneic hematopoietic stem cell transplantation is appropriate and no suitable human leukocyte antigen matched related stem cell donor is available.
Clinical Trial Results and Disease Manifestation Reductions
According to the FDA, the safety and effectiveness of Waskyra were evaluated across two open-label, single-arm, multinational clinical studies and an expanded access program encompassing a total of 27 patients with severe Wiskott-Aldrich syndrome. Data from these programs showed a 93% decrease in the rate of severe infections during the six to 18 months post-treatment period compared to the 12 months prior to treatment. Furthermore, moderate and severe bleeding events dropped by 60% in the first 12 months post-treatment relative to the previous year, with most patients reporting no moderate to severe bleeding four years after treatment.
Mechanism of Action and Treatment Administration
Wiskott-Aldrich syndrome is a rare, life-threatening genetic condition driven by mutations in the WAS gene, which typically causes bleeding, eczema, recurrent infections, and heightened susceptibility to autoimmunity and lymphoreticular malignancies. Waskyra addresses this underlying pathology by utilizing a patient’s own hematopoietic stem cells, which are genetically modified in a laboratory to incorporate functional copies of the WAS gene. Vinay Prasad, M.D., M.P.H., Chief Medical and Scientific Officer and Director of the FDA’s Center for Biologics Evaluation and Research, stated that the therapy uses genetically corrected cells to restore functional WAS protein expression after infusion following reduced-intensity conditioning.
Regulatory Review and Safety Profile
In evaluating the therapy, the FDA utilized regulatory flexibility across four distinct areas: rare disease considerations, clinical trial design, mechanism of action, and chemistry, manufacturing, and controls. Vijay Kumar, M.D., Acting Director of the CBER Office of Therapeutic Products, noted that the approval answers an urgent need for a patient community previously facing life without approved therapies. Common side effects identified during the review process include rash, respiratory tract infection, febrile neutropenia, catheter-related infection, vomiting, diarrhea, liver injury, and petechiae.
