King’s treats first adult patients with ‘incurable’ T-cell leukaemia with new gene therapy
09 December 2025 - Base-edited immune cells help patients achieve remission
King’s College Hospital has used a ground-breaking new treatment, developed by scientists at Great Ormond Street Hospital (GOSH) and University College London (UCL), which uses genome-edited immune cells to treat adults with the rare and aggressive form of blood cancer called T-cell acute lymphoblastic leukaemia (T-ALL).
The world-first gene therapy (BE-CAR7) uses base-edited immune cells to treat previously untreatable T-cell leukaemia and help patients achieve remission, offering new hope for patients facing this aggressive cancer.
Base-editing is an advanced version of CRISPR technology, which can precisely change single letters of DNA code inside living cells.
In 2022, researchers from GOSH and UCL delivered the world’s first treatment made using ‘base-editing’ to a 13-year-old girl. Now a further eight children have undergone the treatment at GOSH and two adults at King’s.
The results of the clinical trial have been published in the New England Journal of Medicine and presented at the 67th American Society of Hematology Annual Meeting.
In 2019, King’s became the first hospital in the UK to use CAR T therapy to treat adult patients with lymphoma, and it has since become available to treat several types of blood cancer. This therapy uses immune cells, called T-cells, and modifies them to have specific proteins on their surface called chimeric antigen receptors (CARs). The CARs can recognise and target specific ‘flags’ on the surface of cancer cells, and the T-cell can then destroy that cancer cell.
BE-CAR7 T-cells are engineered using base editing, a new-generation of genome editing that avoids cutting DNA, reducing the risk of chromosomal damage. Very precise chemical reactions were carried out using CRISPR guidance systems to change single letters of DNA code in order to modify the T cells. As reported in 2022, these complex DNA changes generated storable banks of ‘universal’ CAR T-cells that can find and attack T-cell leukaemia when given to patients.
The ‘universal’ CAR T-cells in this study were made from healthy donor white blood cells and engineering steps were undertaken in a clean room facility at Great Ormond Street Hospital, using custom made RNA, mRNA and a lentiviral vector in an automated process previously developed by the research team.
When base-edited CAR T-cells are given to the patient they rapidly find and destroy all T-cells in the body, including leukemic T-cells. If the leukaemia is eradicated within four weeks, the patient’s immune system is then rebuilt from a bone marrow transplant over a period of several months.
Professor Waseem Qasim who led the research and is Professor of cell and gene therapy at UCL and Honorary consultant immunologist at GOSH, said: “We previously showed promising results using precision genome editing for children with aggressive blood cancer, and this larger number of patients confirms the impact of this type of treatment. We’ve shown that universal or ‘off the shelf’ base-edited CAR T-cells can seek and destroy very resistant cases of CD7+ leukaemia.”
Dr Deborah Yallop, Consultant Haematologist at King’s, said: “We’ve seen impressive responses in clearing leukaemia that seemed incurable – it’s a very powerful approach.”
The trial was sponsored by GOSH and supported by the Medical Research Council, Wellcome, and the National Institute for Health and Care Research (NIHR), for patients eligible for NHS care in the UK. Any patients eligible to receive treatment under the NHS and interested in this trial should approach their specialist healthcare provider.