The US Food and Drug Administration has approved expanded use of the Casgevy gene therapy for patients aged two years and older with sickle cell disease or transfusion-dependent beta thalassaemia. Around 5,500 additional US children become eligible for the one-time CRISPR treatment.
The decision, issued on 1 July 2026, is a supplemental approval. Casgevy had previously been approved for patients aged 12 years and older with either condition. The FDA granted the approval to Vertex Pharmaceuticals, Incorporated.
It is the first gene therapy approved for patients aged two years and older with sickle cell disease.
What the Casgevy gene therapy approval covers
The indication now spans two rare inherited blood disorders. The first is sickle cell disease with recurrent vaso-occlusive crises, the unpredictable episodes of severe pain that frequently require hospitalisation. The second is transfusion-dependent beta thalassaemia.
Casgevy consists of a patient’s own haematopoietic stem cells, edited outside the body using CRISPR/Cas9 and then returned as a single intravenous infusion. The edit raises production of fetal haemoglobin. In sickle cell disease this helps prevent red blood cells from forming abnormal sickle shapes; in transfusion-dependent beta thalassaemia it raises total haemoglobin.
Importantly, the therapy is not a standalone infusion. Patients receive full myeloablative conditioning, a high-intensity preparatory regimen, before treatment.
“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, Acting Director of the FDA’s Center for Biologics Evaluation and Research.
The trial evidence in children
The FDA evaluated Casgevy in children aged five to under 12 years across two trials. In the sickle cell disease trial of 11 patients, all eight patients evaluable for efficacy met the primary outcome: no protocol-defined severe vaso-occlusive crises for at least 12 consecutive months within the first 24 months after infusion.
In the transfusion-dependent beta thalassaemia trial of 15 patients, eight of the nine efficacy-evaluable patients achieved transfusion independence for 12 consecutive months. The median duration of transfusion independence was 20.1 months.
However, the efficacy data submitted covered children aged five to under 12. The regulator granted extrapolation to the younger paediatric population based on product characteristics and the clinical study data, expanding the indication down to two years of age for both conditions.
The most common adverse reactions were mucositis and febrile neutropenia in both patient groups, and decreased appetite in patients with sickle cell disease. The prescribing information carries warnings for neutrophil engraftment failure, delayed platelet engraftment, hypersensitivity reactions and off-target genome editing risk.
A 53-day review under the priority voucher pilot
The FDA granted the approval 53 days after filing. It is the eighth approval selected for the agency’s Commissioner’s National Priority Voucher pilot programme. Casgevy also holds Orphan Drug, regenerative medicine advanced therapy and Fast Track designations.
Meanwhile, the clinical rationale for treating younger patients rests on timing. “Grounded in the scientific evidence that earlier treatment reduces the risk of lasting end-organ damage, making this therapy available to younger patients opens a critical window for intervention,” said Megha Kaushal, Acting Deputy Director of the Office of Therapeutic Products at CBER and a paediatric haematologist.
Vertex chief executive Reshma Kewalramani pointed to the trial results across age groups. “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,” she said.
What happens next in the UK and Saudi Arabia
Vertex has completed regulatory submissions in the United Kingdom and the Kingdom of Saudi Arabia to expand use of Casgevy to children as young as five. Those reviews are ongoing. The age-two indication currently applies in the United States only.
Access in the US runs through a network of independently operated authorised treatment centres. Vertex reports more than 75 activated centres nationally.
As a result, the practical test of this approval will be delivery rather than science. Myeloablative conditioning, stem cell collection and long-term follow-up all demand specialist paediatric capacity. Patients dosed in the trials are being followed for up to 15 years under an ongoing long-term study, which will determine whether early intervention with the Casgevy gene therapy translates into the reduced organ damage its clinical rationale anticipates.
For further coverage of cell and gene therapy developments, see the Life Sciences Global News Biotechnology section. Full details of the decision are available in the FDA press announcement and the Vertex Pharmaceuticals newsroom release.
