19 June 2023

Base-edited T-cell therapy to treat young people with treatment-resistant T-cell leukaemia continues to show promise, according to an ongoing UK study.

Data from an NHS clinical trial, as part of a ‘bench-to-bedside’ collaboration between UCL and Great Ormond Street Hospital for Children (GOSH), reveals today that two of the three young patients with relapsed T-cell leukaemia, who received the treatment, are faring well.

The findings are published in the latest edition of the New England Journal of Medicine.

Last year, 13-year-old Alyssa from Leicester was revealed to be the first person in the world to be treated in a trial for T-cell acute lymphoblastic leukaemia (T-ALL).

Within four weeks of receiving the base-edited CAR-T cells, Alyssa’s leukaemia was undetectable. She went on to have a successful bone marrow transplant and is still well and at home almost a year later.

A second teenager cleared their leukaemia within a similar time period and is now recovering at home after their transplant. A third child responded to the CAR T-cell therapy, but their course was complicated by serious infections and had to move to palliative care, the researchers report.

This first human application of base-editing technology was designed and developed by Professor Waseem Qasim, of UCL Great Ormond Street Institute of Child Health, and a team of researchers at UCL, with Dr Robert Chiesa and the Bone Marrow Transplant/CART/Haematology teams at GOSH. 

Dr Chiesa said: “It is really crucial that children affected by cancer, who failed standard of care, have access to innovative strategies in the context of clinical trials such as this. A research hospital such as GOSH offers the ideal setting for developing experimental approaches that might offer hope to children with otherwise very poor prognosis. This is possible due to the dedication of scientists, doctors, nurses and allied professionals working for these children and their families.”

To generate banks of ‘universal’ anti T-cell CAR T-cells, the researchers used healthy donor T-cells, arranged by the Anthony Nolan registry. They used base editing to make changes to the cells’ DNA, chemically converting single nucleotide bases to effectively ‘knock-out’ certain genes. This means that the CAR-T cells do not attack each other, and are a universal treatment, rather than having to be made from each individual’s own T cells.

The clinical trial is still open and aims to recruit up to ten NHS patients with T-cell leukaemia, after they have exhausted all conventional treatment options, referred by NHS children’s leukaemia specialists.

If the treatment is shown to be widely successful, the team hopes to offer it to more children and earlier in their treatment.

The researchers also believe the base editing technique could be used for multiple other conditions, where changes in single letters of DNA cause illness, such as sickle cell disease.

Prof Qasim said: “The technology itself could also have wide reaching applications for corrections of certain inherited conditions such as sickle cell disease. As the technology matures and is shown to be safe, it could be applied quite widely, although there will need to be careful testing and longer-term studies.”


Chiesa R, Georgiadis C, Syed F, Zhan H, Etuk A, Gkazi SA, Preece R, Ottaviano G, Braybrook T, Chu J, Kubat A, Adams S, Thomas R, Gilmour K, O'Connor D, Vora A, Qasim W; for the Base-Edited CAR T Group. (2023) “Base-edited CAR7 T Cells for relapsed T-cell acute lymphoblastic leukaemia.” New England Journal of Medicine, doi: 10.1056/NEJMoa2300709

Link: https://www.nejm.org/doi/10.1056/NEJMoa2300709

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