The U.S. Food and Drug Administration issued a supplemental approval on July 1, 2026, expanding Casgevy (exagamglogene autotemcel) to patients aged 2 years and older with either sickle cell disease (SCD) involving recurrent vaso-occlusive crises (VOCs) or transfusion-dependent β thalassemia (TDT). The agency said this is the first gene therapy approved for patients aged 2 years and older with SCD. Casgevy was previously approved for patients aged 12 years and older with these conditions.

Casgevy consists of the patient’s own autologous hematopoietic blood stem cells. The cells are edited using CRISPR/Cas9 and administered as a one-time intravenous infusion before being engrafted in the body’s bone marrow. The treatment is preceded by full myeloablative conditioning, a high-intensity preparatory treatment used before a stem cell transplant or gene therapy. In patients with severe SCD, Casgevy increases fetal hemoglobin, or HbF, which helps prevent red blood cells from forming abnormal sickle shapes and addresses the underlying cause of the disease. In patients with TDT, it increases HbF and total hemoglobin levels, eliminating dependence on regular red blood cell transfusions.

Clinical evidence and safety information

Safety and effectiveness in patients aged 5 years to less than 12 years with SCD were evaluated in a clinical trial involving 11 patients. All eight patients evaluable for efficacy achieved the primary outcome of VF12: no protocol-defined severe VOCs for at least 12 consecutive months within the first 24 months after infusion. In a TDT trial involving 15 patients in the same age range, eight of nine efficacy-evaluable patients achieved transfusion independence for 12 consecutive months, with a median duration of transfusion independence of 20.1 months. Based on product characteristics and clinical study data, the FDA granted extrapolation to the younger pediatric population and expanded the indication to patients aged 2 years and older for both conditions.

  • Common adverse reactions in patients with SCD and TDT included mucositis and febrile neutropenia.
  • Decreased appetite was also reported in patients with SCD.
  • Warnings include neutrophil engraftment failure, delayed platelet engraftment, hypersensitivity reactions, and off-target genome editing risk.

“With today’s decision, pediatric patients as young as 2 years of age can now access a critical additional treatment option to treat these debilitating, life-threatening diseases,” said Karim Mikhail, B. Pharm., M.S., Acting Director of the Center for Biologics Evaluation and Research. The FDA said the approval decision was granted 53 days after filing and was the eighth approval selected for the Commissioner’s National Priority Voucher pilot program. Casgevy also received Orphan Drug, regenerative medicine advanced therapy (RMAT), and Fast Track designations. The FDA granted the approval to Vertex Pharmaceuticals, Incorporated.