New clinical data for Casgevy in younger SCD/TDT patients age 5-11 show efficacy and safety consistent with older populations.
RT’s Three Key Takeaways:
- Pediatric Expansion: Vertex presented the first clinical data for Casgevy in children ages 5 to 11 with severe sickle cell disease and transfusion-dependent beta thalassemia, showing results consistent with older patient populations.
- Regulatory Timeline: The company expects to begin global regulatory submissions for the 5 to 11 age group in the first half of 2026 and plans to use an FDA priority voucher to accelerate the review.
- Long-term Efficacy: Updated data for patients 12 and older show that 100% of sickle cell patients remained free of vaso-occlusive crises for a mean of 35.3 months, according to a news release.
Vertex Pharma announced data from multiple studies demonstrating the clinical benefits of Casgevy (exagamglogene autotemcel) in patients ages 5 and older with severe sickle cell disease (SCD) or transfusion-dependent beta thalassemia (TDT). The results, presented at the American Society of Hematology Annual Meeting, included the first clinical data for children ages 5 to 11.
Casgevy is currently approved for eligible patients 12 years of age and older in the US, Canada, Great Britain, and the European Union, among other regions.
Vertex expects to initiate global regulatory submissions for the younger age group, including a supplemental Biologics License Application to the US FDA, in the first half of 2026.
“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, executive vice president, global medicines development and medical affairs, and chief medical officer at Vertex, in a news release.
Pediatric Study Results
Dosing is complete for the 5 to 11 age group cohort in the pivotal studies, and efficacy and safety data are consistent with the profiles established in older patients, according to the news release.
Vertex also presented longer-term data for patients 12 and older. As of April 2025, 100% of SCD patients (45/45) achieved freedom from vaso-occlusive crises (VOCs) for a mean duration of 35.3 months. In patients with TDT, 98.2% (55/56) achieved transfusion independence for a mean duration of 41.4 months, according to the news release.
“I am excited to hopefully be able to offer this option to my younger patients soon, early in life, before some of the most devastating impacts of these diseases begin,” said Haydar Frangoul, medical director of pediatric hematology and oncology at Sarah Cannon Research Institute and HCA Healthcare’s TriStar Centennial Children’s Hospital, in a news release.
Mechanism and Safety Profile
Casgevy is a non-viral, ex vivo CRISPR/Cas9 gene-edited cell therapy. The treatment involves editing a patient’s own hematopoietic stem cells to produce high levels of fetal hemoglobin in red blood cells, which can eliminate VOCs and the need for regular transfusions, according to the news release.
The safety profile is consistent with myeloablative conditioning and autologous transplant. Common side effects include nausea, fatigue, fever, and low levels of white blood cells or platelets. The treatment process involves a conditioning medicine that clears cells from the bone marrow, which may impact a patient’s ability to become pregnant or father a child, according to the news release.
Vertex received a Commissioner’s National Priority Voucher from the FDA for this age group, which will provide a shorter review clock of one to two months once the application is submitted, according to the news release.
