FDA Approves Etuvetidigene Autotemcel (Waskyra) For Wiskott-Aldrich Syndrome

The US Food and Drug Administration has approved etuvetidigene autotemcel (Waskyra), the first cell-based gene therapy for the treatment of Wiskott-Aldrich syndrome (WAS).1

As described in a December 9, 2025, release from the Agency, etuvetidigene autotemcel is indicated for pediatric patients ≥ 6 months of age and adults with WAS who have a mutation in the WAS gene and for whom hematopoietic stem cell transplantation (HSCT) is appropriate and no suitable human leukocyte antigen (HLA)-matched related stem cell donor is available.

“Today’s approval is a transformative milestone for patients with Wiskott-Aldrich syndrome, offering the first FDA-approved gene therapy that uses the patient's own genetically corrected hematopoietic stem cells to treat the disease,” Vinay Prasad, MD, MPH, Chief Medical and Scientific Officer and Director of the FDA’s Center for Biologics Evaluation and Research, said in a statement. “The FDA continues to exercise flexibility in the regulatory approach for rare diseases by considering all available data sources, including as appropriate data from expanded access programs, to facilitate the advancement of life-changing treatments while ensuring scientific requirements are satisfied.”

WAS is a rare, X-linked, life-threatening inborn error of immunity and platelet disorder caused by WAS protein (WASP)-encoding gene mutations. It is characterized by thrombocytopenia, bleeding events, recurrent and severe infections, eczema, and increased risk of immune dysregulation and malignancy. While allogeneic HSCT can be curative, it is still hampered by limited donor availability and potential complications.2

Etuvetidigene autotemcel consists of the patient’s own hematopoietic stem cells (HSCs), which have been genetically modified to include functional copies of the WAS gene. Following reduced-intensity conditioning, the gene-corrected cells are infused intravenously to restore blood cell production. Etuvetidigene autotemcel restores functional WAS protein expression in affected cells, addressing the underlying cause of the disease.

Of note, during the review of etuvetidigene autotemcel, the FDA exercised appropriate regulatory flexibility across rare disease considerations, clinical trial design, mechanism of action, and chemistry, manufacturing and controls (CMC), enabling approval and timely access to the product while carefully balancing preapproval data requirements with post-market commitments. The FDA permitted the use of relevant manufacturing and quality data submitted to this BLA from a similar, approved product that was justified to be adequately representative of etuvetidigene autotemcel for these purposes.

Its safety and effectiveness was assessed in 2 open-label, single-arm, multinational clinical studies and an expanded access program totaling 27 patients with severe WAS, which demonstrate substantial and sustained clinical benefit for patients with severe WAS, with significant reductions in the primary disease manifestations that drive morbidity and mortality.

The rate of severe infections decreased by 93% in the 6 to 18 months post-treatment period compared to the rate 12 months before treatment. Similarly, moderate and severe bleeding events were reduced by 60% in the first 12 months post-treatment compared to the year prior to treatment. Of note, most patients did not report moderate to severe bleeding after 4 years post treatment.

As described by the FDA, the most common side effects associated with treatment include rash, respiratory tract infection, febrile neutropenia, catheter related infection, vomiting, diarrhea, liver injury, and petechiae.

“Today’s approval addresses the urgent need in the WAS community, where patients have described living 'a life of terrifying worry and fear' without any approved therapies available,” Vijay Kumar, MD, Acting Director of the CBER Office of Therapeutic Products, said in a statement. “This action marks significant progress in the development of much-needed treatment options for patients affected by this debilitating and life-threatening disease, enabling them to engage in everyday activities such as going to school or participating in sports.”

References

1. FDA. FDA Approves First Gene Therapy Treatment for Wiskott-Aldrich Syndrome. December 9, 20225. Accessed December 9, 2025. https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treatment-wiskott-aldrich-syndrome

2. Ferrua F, Cenciarelli S, Giannelli S, et al. Lentiviral hematopoietic stem and progenitor cell gene therapy with Etuvetidigene autotemcel for the treatment of Wiskott-Aldrich Syndrome. Blood. https://doi.org/10.1182/blood-2025-6092