MHRA Expands Casgevy Approval to Children Aged 5 and Older for Two Genetic Disorders
Key Facts
The UK Medicines and Healthcare products Regulatory Agency (MHRA) expanded Casgevy’s authorization to cover eligible children aged 5 and older with severe sickle cell disease or transfusion-dependent beta thalassemia. The agency granted the expansion to Vertex Pharmaceuticals (Europe) Ltd on October 29, 2026, and published its announcement on October 30. The decision lowers the minimum age in the UK, where the previous authorization covered patients aged 12 and older for the same two conditions. It brings a younger age group within the scope of regulatory approval, while eligibility remains tied to the two specified diagnoses. The MHRA said its approval expands the use of gene therapy in the country for children who meet these criteria.
Casgevy works by editing a defective gene in stem cells taken from a patient’s bone marrow. The cells are first collected, then modified in a laboratory before being returned to the patient’s body by infusion. A conditioning treatment precedes the return of the cells, and patients may need to remain in hospital after the infusion. The process is associated with side effects including nausea, fatigue and fever, as well as an increased risk of infection, according to the MHRA. These requirements show that the expansion concerns a treatment involving the collection and processing of a patient’s cells before they are reintroduced, rather than a standalone drug prescription.
Data cited by the US Food and Drug Administration (FDA) included separate results for children in each of the two diseases. In the sickle cell disease trial, all eight patients evaluable for efficacy achieved the primary outcome: no severe vaso-occlusive crises for at least 12 consecutive months within the first 24 months after infusion. In the transfusion-dependent beta thalassemia trial, 8 of 9 evaluable patients achieved transfusion independence for 12 consecutive months. The median duration of transfusion independence in that trial was 20.1 months, according to the FDA. These figures show outcomes for the evaluable trial groups for each disease separately.
The scope of US approval was broader than the UK expansion in terms of age. On July 1, 2026, the FDA expanded its approval to cover patients aged 2 and older for both conditions, after previously authorizing use from age 12. The agency said expanding the indication to this age group was based on product characteristics and clinical study data, with results extrapolated to younger children. The expanded UK authorization therefore starts at age 5, while the US scope starts at age 2. The comparison places the two regulatory decisions in different age contexts, with each covering the two conditions mentioned.
The MHRA said about 15,000 people in the UK have sickle cell disorder. NHS England had announced that Casgevy would be available through the health service in England to eligible patients with severe sickle cell disease from January 31, 2025, noting at the time that the treatment was approved for older children and adults. The regulatory expansion announcement alone does not set a date for making the treatment available through the NHS to newly eligible children. The MHRA is due to publish the product characteristics summary and patient information on its products website within 7 days of approval. The agency said it will continue to monitor the treatment’s safety and effectiveness.