Waskyra Wins FDA Approval as First Gene Therapy for Wiskott-Aldrich Syndrome

The FDA has approved Waskyra (etuvetidigene autotemcel), a cell-based gene therapy for children aged six months and older and adults with Wiskott-Aldrich syndrome. The therapy is intended for patients with a WAS gene mutation who are eligible for stem cell transplantation but lack a suitable related donor.

This is the first FDA-approved gene therapy for this condition, offering a new option for a rare and life-threatening immunodeficiency that primarily affects males. The FDA’s approval includes required post-marketing studies.

Waskyra was developed by Fondazione Telethon in Italy, which is the first non-profit organization to obtain FDA approval for a cell-based gene therapy.

Wiskott-Aldrich syndrome is a rare X-linked primary immunodeficiency caused by mutations in the WAS gene. It typically presents in infancy with thrombocytopenia, recurrent infections and eczema.

Children experience easy bruising and bleeding from low platelet counts, along with recurrent bacterial and viral infections due to immune dysfunction. Many also develop autoimmune complications or lymphoid cancers as they grow older.

NIH sources estimate an incidence of roughly one in 100000 live births, though milder cases may go unrecognized.

X-linked disorders arise from mutations on the single X chromosome in males, meaning even one faulty gene can cause disease, while females often carry the mutation with milder or no symptoms. Wiskott-Aldrich syndrome is among more than 500 disorders linked to genes on the X chromosome.

Waskyra is part of a broader effort to develop genetic treatments for X-linked diseases. Ongoing programs across the landscape include gene therapy candidates for X-linked retinitis pigmentosa and X-linked sideroblastic anemia, as well as in vivo hematopoietic stem cell-directed gene insertion now in early clinical testing for X-linked chronic granulomatous disease.

Waskyra is an ex vivo autologous gene therapy that uses a patient’s own CD34+ hematopoietic stem cells. These cells are modified with a lentiviral vector to add a functional WAS gene and reinfused after reduced-intensity conditioning.

Once engrafted, they produce blood and immune cells with functional WAS protein. The therapy is administered as a single intravenous infusion.

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Lentiviral vectors have become a central delivery platform in gene therapy, supporting long-term gene expression in a range of inherited and acquired diseases.

Evidence supporting the approval comes from two open-label, single-arm multinational studies and an expanded access program that enrolled 27 patients with severe disease.

With no comparator arm, outcomes were measured by comparing clinical events before and after treatment. Severe infections decreased by 93% in the six to 18 months following treatment compared with the prior year, and moderate to severe bleeding events fell by 60% in the first year post-treatment. Many patients reported no moderate or severe bleeding four years after infusion.

Common side effects included rash, respiratory infections, febrile neutropenia, catheter-related infections, vomiting, diarrhea, liver injury and petechiae. No adverse reactions were directly linked to etuvetidigene autotemcel, though mobilization, pre-treatment and conditioning steps carry their own risks.

The FDA noted that it applied regulatory flexibility appropriate for a rare, life-threatening disease, drawing on clinical trial data, expanded access experience and relevant manufacturing details from a similar approved product.

The therapy may help reduce infections and bleeding episodes that affect daily activities. Researchers involved in development emphasized the importance of providing an option for patients who do not have a compatible donor for transplantation.

Waskyra holds Orphan Drug, Rare Pediatric Disease and Regenerative Medicine Advanced Therapy designations.

Prior to the FDA’s decision, the European Medicines Agency (EMA) issued a positive opinion on Waskyra following its own independent review.

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