Vertex's Casgevy becomes first approved gene therapy for young kids with rare blood disorders

Vertex Pharmaceuticals said Wednesday the FDA approved a pediatric expansion of its gene therapy Casgevy for children 2 years and older with sickle cell disease and transfusion-dependent beta thalassemia. The approval makes Casgevy the first genetic medicine for these indications available to young children, according to Vertex's news release. The therapy had previously been approved for patients 12 and older. The FDA said the decision was granted 53 days after filing and represented the eighth approval under its Commissioner's National Priority Voucher program. Casgevy received the accelerated review designation in November 2025 and Vertex completed its submission on May 4. The FDA said Casgevy was assessed in a study of 11 sickle cell patients aged 5 to less than 12 years. None of the eight evaluable patients experienced severe vaso-occlusive crises for at least 12 consecutive months within two years of infusion. In a beta thalassemia trial with 15 patients in the same age range, eight of nine evaluable participants no longer needed transfusions for 12 consecutive months. The FDA said approval for patients as young as 2 was based on extrapolation to the younger pediatric population. Vertex said it is running Phase 3 studies to test Casgevy in this age group. The therapy was developed with CRISPR Therapeutics.