The UK medicines regulator has extended the authorisation of Casgevy to eligible children aged five and over with severe sickle cell disease or transfusion-dependent beta-thalassaemia. The decision was issued on 29 October 2026 and announced the following day. Previously, the UK authorisation covered patients aged 12 and over. The MHRA announcement stresses that younger children must still meet the treatment’s eligibility requirements.
How Casgevy changes haemoglobin production
Casgevy contains exagamglogene autotemcel and uses a patient’s own blood-forming stem cells. These are collected, modified outside the body and returned through an infusion. The treatment therefore involves several clinical stages, rather than a medicine taken regularly at home.
According to the product information, CRISPR/Cas9 technology targets a regulatory region of the BCL11A gene. This is intended to increase production of fetal haemoglobin, which normally plays an important role before birth. It does not simply replace a faulty gene for adult haemoglobin.
In sickle cell disease, fetal haemoglobin helps reduce the sickling of red blood cells. In beta-thalassaemia, it helps compensate for inadequate production of the beta-globin component of haemoglobin. Both conditions affect the blood’s ability to carry oxygen, although symptoms and treatment needs vary between patients.
Preparation and monitoring remain part of treatment
Before the modified cells are returned, patients undergo conditioning treatment to prepare their bone marrow. A hospital stay follows while clinicians monitor the cells’ engraftment and the recovery of blood-cell production. The MHRA lists nausea, tiredness, fever and an increased risk of infection among associated adverse effects. The regulator says it will continue monitoring safety and effectiveness.
A wider authorisation, rather than an immediate rollout
The UK first approved the therapy in November 2023. That decision drew on trials in an older age group, in which assessed patients achieved periods without severe painful crises or without transfusions. Those findings should not automatically be presented as results for the younger children covered by the new decision.
The October announcement expands the UK marketing authorisation. It does not mean that every child with either condition will receive treatment, and it does not provide a treatment-start timetable or announce a new reimbursement arrangement. Nor does a UK regulatory decision establish a change in access in other countries.
Sources: MHRA — expanded authorisation, October 2026, Electronic Medicines Compendium — product information, MHRA — initial authorisation, November 2023.
