BOSTON, June 11, 2026
Vertex Pharmaceuticals announced new Phase 3 clinical data demonstrating the potential of CASGEVY® (exagamglogene autotemcel) in children aged 5–11 years with severe sickle cell disease (SCD) and transfusion-dependent beta thalassemia (TDT). The results, presented at the European Hematology Association (EHA) Congress 2026 and simultaneously published in the New England Journal of Medicine (NEJM), showed that the gene-editing therapy delivered strong efficacy and a safety profile consistent with previous studies in adolescents and adults. The company also confirmed ongoing regulatory reviews in the United States and additional submissions in the United Kingdom and Saudi Arabia aimed at expanding access to younger patients.
CASGEVY Demonstrates Transformative Clinical Outcomes in Pediatric Patients
Vertex reported that data from the Phase 3 CLIMB-151 study showed that all 11 children with severe sickle cell disease treated with CASGEVY remained free from vaso-occlusive crises (VOCs) following treatment. Among patients with sufficient follow-up, 100% (8/8) achieved the primary endpoint of remaining VOC-free for at least 12 consecutive months, with a mean VOC-free duration of 19 months. In the Phase 3 CLIMB-141 study involving children with transfusion-dependent beta thalassemia, 100% of evaluable patients (8/8) achieved transfusion independence for at least 12 consecutive months while maintaining healthy hemoglobin levels. The findings highlight the potential of CASGEVY as a one-time gene-editing therapy capable of significantly reducing disease burden in children affected by severe inherited blood disorders.
Durable Efficacy and Consistent Safety Profile Observed
According to Vertex, children treated with CASGEVY demonstrated durable increases in fetal hemoglobin (HbF) and stable gene-editing activity throughout the follow-up period. The therapy’s safety profile remained consistent with expectations for autologous stem cell transplantation and myeloablative conditioning. The company noted that one patient with beta thalassemia died from severe veno-occlusive disease associated with busulfan conditioning; however, the event was determined to be unrelated to CASGEVY treatment. Overall, the data support the long-term therapeutic potential of the CRISPR/Cas9-based therapy and reinforce previously reported clinical benefits observed in older patient populations.
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Regulatory Expansion Efforts Continue Globally
Vertex confirmed that the U.S. Food and Drug Administration (FDA) is currently reviewing an application to expand CASGEVY use to children aged 5–11 years. The company has also completed regulatory submissions in the United Kingdom and Kingdom of Saudi Arabia to support pediatric approval. CASGEVY is currently approved in multiple countries for eligible patients aged 12 years and older with sickle cell disease or transfusion-dependent beta thalassemia. The new pediatric data strengthen Vertex’s regulatory strategy and support broader access to what is recognized as the world’s first approved CRISPR/Cas9 gene-editing therapy.
Early Intervention Could Improve Long-Term Patient Outcomes
Sickle cell disease and transfusion-dependent beta thalassemia are serious inherited blood disorders that often begin causing complications in early childhood. Recurrent vaso-occlusive crises, chronic anemia, transfusion dependence, and progressive organ damage can significantly reduce quality of life and life expectancy. By demonstrating strong clinical outcomes in younger patients, CASGEVY may provide an opportunity for earlier intervention before irreversible disease complications occur. The latest findings further establish the therapy’s potential to transform the treatment landscape for pediatric patients living with these rare hematologic diseases.
Source: Vertex Pharmaceuticals press release
