BOSTON — Vertex Pharmaceuticals released new clinical data showing that its gene-editing therapy CASGEVY (exagamglogene autotemcel) demonstrated strong and durable benefits in children ages 5–11 years with severe sickle cell disease or transfusion-dependent beta thalassemia. The results, presented at the American Society of Hematology Annual Meeting, mark the first clinical data ever reported for a genetic therapy in this age group. Vertex said it plans to begin global regulatory submissions for the pediatric indication in the first half of 2026.
CASGEVY is currently approved for people ages 12 years and older with sickle cell disease or transfusion-dependent beta thalassemia in the United States, Great Britain, the European Union, the Gulf region, Canada, Switzerland and the United Arab Emirates.
“These results — the first clinical data ever presented on any genetic therapy for children ages 5–11 years with SCD — again demonstrate the transformative potential of CASGEVY,” said Carmen Bozic, M.D., executive vice president, global medicines development and medical affairs, and chief medical officer at Vertex. “With dosing completed in the 5–11 age group and the Commissioner’s National Priority Voucher for CASGEVY in this population in hand, we are excited to begin global regulatory filings in the first half of next year.”
Haydar Frangoul, M.D., M.S., medical director of pediatric hematology and oncology at the Sarah Cannon Research Institute and HCA Healthcare’s TriStar Centennial Children’s Hospital, said real-world use in older patients underscores the therapy’s impact. “I have seen firsthand the transformative effect this therapy has had on older patients with SCD or TDT,” he said. “I am excited to hopefully offer this option to my younger patients soon, before some of the most devastating complications develop.”
Data from children ages 5–11 years treated with CASGEVY
In the Phase 3 CLIMB-151 trial in sickle cell disease, 11 children have been dosed and all four with sufficient follow-up achieved the primary endpoint of remaining free from vaso-occlusive crises for at least 12 consecutive months. No patient experienced a vaso-occlusive crisis after infusion, with the longest VOC-free duration lasting about two years.
In the Phase 3 CLIMB-141 trial for transfusion-dependent beta thalassemia, 13 children have been dosed and all six with sufficient follow-up achieved transfusion independence for at least 12 months while maintaining hemoglobin levels of at least 9 g/dL. Twelve of 13 children are now transfusion free, with durations approaching two years. One participant died from pneumonia in the setting of multi-organ failure related to busulfan conditioning.
Across both studies, the safety profile in younger patients was consistent with what has been seen in older patients. Children experienced durable increases in fetal hemoglobin and stable allelic editing.
Longer-term results in patients ages 12 and older
Vertex also reported updated longer-term results from pivotal studies in people ages 12 and above. As of April 2025, all 45 patients in sickle cell disease trials achieved at least 12 consecutive months free from vaso-occlusive crises, with a mean VOC-free duration of more than 35 months. In beta thalassemia, 55 of 56 patients achieved at least 12 months of transfusion independence, with an average duration exceeding 41 months. The safety profile remained consistent with myeloablative conditioning and autologous transplant in both diseases.
Vertex said the new data further validate CASGEVY’s clinical durability and support its plans to seek regulatory approval for use in children 5–11 years old. (Source: IANS)
