A new study by scientists at University College London and Great Ormond Street Hospital has demonstrated promising results in the treatment of T-cell acute Lymphoblastic Leukaemia (T-ALL), a rare and aggressive blood cancer
What the study reveals.
This groundbreaking research introduces BE-CAR7, a world-first base-edited Chimeric antigen receptor (CAR) T-cell therapy used in humans. The treatment uses gene editing to change donor immune cells to target T-cell acute lymphoblastic leukaemia, an aggressive and rare blood cancer previously thought of as incurable. Significantly, this is the first time multiple precise DNA edits have been used to create universal donor immune cells for cancer treatment.
Challenges in treating T-cell leukaemia
T-ALL is a rare cancer with poor outcomes and limited treatment options when standard therapy fails. Conventional CAR-T treatments are largely ineffective, as engineered cells kill and attack each other. Many patients treated in this trial had exhausted chemotherapy and bone marrow transplants, demonstrating the need for new approaches.
How base editing works
Base editing is a next-generation form of CRISPR technology that changes single letters of DNA without cutting the DNA strand. This approach reduces the risk of chromosomal damage and enables highly targeted, multistep editing.
The key edits in engineered cells:
The engineered BE- CAR7 cells undergo four critical DNA edits that make therapy possible:
- Remove natural T-cell receptors – donor cells become “universal”.
- Remove CD7 – prevents the therapy from destroying itself (“friendly fire”).
- Remove CD52 – protects the cells from an antibody drug during treatment.
- Add a CAR receptor targeting CD7 – allows edited cells to find and kill T-ALL.
These steps demonstrate the core technical innovation of the study, which is central to the breakthrough therapy.
How the treatment is given
- Patients receive the edited CAR T-cells.
- The cells immediately wipe out all T-cells in the body (healthy + cancerous).
- If leukaemia is cleared within four weeks, the patient receives a bone marrow transplant to rebuild the immune system.
Results of the clinical trial
Across 10 patients (eight children, two adults) results from the study show:
- 82% achieved a very deep remission.
- 64% remain disease-free.
- The earliest patients have been in remission and off treatment.
- Side effects were expected and manageable; main risks were infections during immune rebuilding.
- Some cancers escaped by losing the CD7 marker.
The patient story: Alyssa’s case
Alyssa Tapley, first treated with BE-CAR7 in 2022 at age 13, had exhausted all available options; chemotherapy and a bone marrow transplant had both failed, and palliative care was being considered. At 16, she is cancer-free, enjoying normal teenage activities, and wants to become a blood cancer researcher.
The significance for medicine
This breakthrough demonstrates that multi-edit-based cell therapies can be delivered safely and effectively. It shows that “off-the-shelf” donor cell banks are feasible, offering new hope for the roughly 20% of children who don’t respond to the standard treatments. Although still in the early stages, this therapy represents a major step forward in developing precise, life-saving treatments for aggressive blood cancers.
Who developed and funded the research
The bE-CAR7 therapy was developed through a collaboration between Great Ormond Street Hospital (GOSH), University College London (UCL), and King’s College Hospital. Funding was provided by the NIHR, Wellcome, Medical Research Council, and the GOSH charity. Donor cell support was supplied by Anthony Nolan. Read the published research paper for more information.
What happens next
Due to over £2 million in new funding, 10 more patients will have access to the BE CAR7 treatment. Researchers are investigating why some cancers lose CD7 and how long the edited cells persist, to improve long-term outcomes. This approach could become part of a standard treatment pathway for resistant T-ALL.
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