New Treatments17 August 2026

Gene editing reaches the clinic: what CRISPR therapy means for younger patients

The first approved CRISPR-based medicine treats sickle cell disease from age 12. Extending it to younger children raises questions about conditioning, fertility and timing.

By NextGenHealth Editorial Team2 min read

A glowing golden DNA double helix made of tiny particles — Photo: Anirudh / Unsplash

In brief

Exa-cel, the first CRISPR medicine, treats sickle cell disease from age 12. What gene editing in younger children means for conditioning and fertility.

In November 2023 the UK’s MHRA became the first regulator in the world to approve a CRISPR-based medicine, exagamglogene autotemcel (exa-cel), for sickle cell disease and transfusion-dependent beta thalassaemia. The FDA approved it for sickle cell disease the following month and for beta thalassaemia in January 2024, in both cases for patients aged 12 and over.

How it works

Exa-cel is an ex vivo therapy. Blood stem cells are collected from the patient, edited in the laboratory to switch off a genetic regulator called BCL11A, and returned to the patient. Switching off BCL11A reactivates production of fetal haemoglobin, the form made before birth, which does not sickle and compensates for the faulty adult haemoglobin.

The burden is not the edit

The hardest part for patients is not the gene editing itself. To make room for the edited cells, patients receive high-dose chemotherapy, usually busulfan, which wipes out their existing bone marrow. That conditioning carries serious risks, including infertility, and requires a prolonged hospital stay.

For adolescents, that means fertility preservation discussions before treatment. For younger children, the same considerations apply with added complexity.

The case for younger patients

Sickle cell disease causes damage from early childhood, including strokes, organ injury and repeated painful crises. Treating earlier could prevent damage that accumulates over years. Trials in children younger than 12 are under way.

What would change the equation

Gentler conditioning regimens, possibly using antibodies rather than chemotherapy, would make the risk-benefit balance far more favourable for young children. In vivo editing, which would deliver the editing machinery directly into the body without removing cells, is the longer-term goal. Both would also help with the other major barrier: delivering complex, expensive treatment in the countries where most children with sickle cell disease live.

Gene editing
CRISPR
Sickle cell disease
Beta thalassaemia

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