FDA Approves Vertex and CRISPR's Casgevy for Young Children with Sickle Cell and Beta Thalassemia
On July 1, 2026, the U.S. Food and Drug Administration (FDA) approved the expanded use of Casgevy (exagamglogene autotemcel) for the treatment of pediatric patients aged 2 to 11 years who have either severe sickle cell disease (SCD) with recurrent vaso-occlusive crises (VOCs) or transfusion-dependent beta thalassemia (TDT).
This landmark decision makes Casgevy—a non-viral, ex vivo CRISPR/Cas9 gene-edited cell therapy—the first and only approved genetic therapy for children as young as 2 years old for both conditions. The label expansion is expected to make approximately 5,500 additional children in the U.S. eligible for the one-time curative treatment, building on its initial December 2023 approval for patients aged 12 and older.
Clinical Data and Pediatric Impact
The approval was supported by data from the ongoing Phase 3 open-label CLIMB-141 and CLIMB-151 clinical trials, which are evaluating the safety and efficacy of a single dose of Casgevy in pediatric patients aged 2 to 11.
The therapy works by editing the patient’s own hematopoietic stem and progenitor cells at the erythroid-specific enhancer region of the BCL11A gene. This precise edit disables the molecular switch that halts fetal hemoglobin (HbF) production after birth, allowing the body to produce high levels of HbF to prevent red blood cells from sickling or to compensate for deficient adult hemoglobin.
Clinical and Corporate Perspectives
"Today’s approval offers renewed hope for children living with sickle cell disease or transfusion‑dependent beta thalassemia. Earlier access to the transformative potential of this therapy will allow clinicians and families to consider treatment before years of cumulative damage from these life-shortening diseases take hold.1" — Haydar Frangoul, M.D., M.S., investigator and Medical Director of HCA Healthcare’s Sarah Cannon Transplant and Cellular Therapy Program
"Just as we redefined what is possible in cystic fibrosis, our ambition is to transform the future for people living with sickle cell disease and transfusion-dependent beta thalassemia. The remarkable consistency of results across age groups reinforces the potential of CASGEVY to deliver durable, transformative benefits to those who have historically had limited options." — Reshma Kewalramani, M.D., Chief Executive Officer and President of Vertex
Safety and Logistics
The safety profile of Casgevy in younger children is consistent with that observed in older cohorts. The most common Grade 3 or 4 non-laboratory adverse reactions include mucositis, febrile neutropenia, and decreased appetite. The treatment requires a myeloablative conditioning regimen (typically busulfan), which carries risks of temporary severe cytopenias and long-term infertility.
To facilitate administration, Vertex has activated a network of over 75 authorized treatment centers (ATCs) across the United States.2 Regulatory reviews for similar pediatric label expansions are currently underway in the United Kingdom and the Kingdom of Saudi Arabia.
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An instance of Early pediatric label expansion requires extending adult data through consistent biological extrapolation. — Consistent product efficacy across groups allowed regulators to expand curative genetic labels to toddlers, avoiding years of progressive physiological damage. ↩︎
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An instance of No medical breakthrough can bypass the physical limits of real-world clinical logistics. — This shows that even a landmark gene therapy requires a complex, multi-site network of specialized medical centers to bypass high-intensity physical logistics. ↩︎