Media release

From: Great Ormond Street Hospital, UK

Ready-made’ T-cell gene therapy tackles ‘incurable’ T-Cell leukaemia

A groundbreaking new treatment using gene-edited immune cells, developed by scientists at Great Ormond Street Hospital (GOSH) and University College London (UCL), has shown promising results in helping children and adults fight a rare and aggressive form of blood cancer called T-cell acute lymphoblastic leukaemia (T-ALL).

The world-first gene therapy uses advanced gene editing technology with immune cells to treat previously untreatable T-cell leukaemia and help patients achieve remission, offering new hope for families facing this aggressive cancer.

In 2022, researchers from GOSH and UCL delivered the world’s first treatment made using ‘base-editing’ to a 13-year-old girl from Leicester, Alyssa. She kindly shared her story with us in 2022.

Now a further eight children and two adults have undergone the treatment at GOSH and King’s College Hospital (KCH).

The results of the clinical trial have been published in the New England Journal of Medicine and presented at the American Society of Hematology Annual Meeting 2025.

Key findings from the study include:

• 82% of patients achieved very deep remissions after BE-CAR7, enabling them to proceed to stem cell transplant without disease
• 63% remain disease-free, with the first patients now three years disease-free and off treatment

Anticipated side effects including low blood counts, cytokine release syndrome and rashes were tolerable, with the greatest risks arising from virus infections until immunity recovered

Using new technology to fight cancer

Immunotherapy using CAR-T cells has recently 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 a specific protein on the surface of the cancer cells, and the T-cell attached can then destroy that cancer cell. Developing CAR T-cell therapy for leukaemia derived from abnormal T-cells has been challenging.

BE-CAR7 cells are engineered using base editing, a new-generation of genome editing that avoids cutting DNA.

The team used the technique to make multiple precise chemical changes to the DNA of healthy donor T-cells, arranged by the Anthony Nolan registry, so cells do not need to be collected from the patient.

The changes were:

• Changing the donor T-cells so that they aren't attacked by the patients own immune system
• Removing a ‘flag’ on the modified T-cells that means they won't attack each other before they can be used as a treatment
• Removing a second ‘flag’ that means the cells are invisible to other cancer treatments
• Adding a way for the modified cells to now recognise and attack cancerous T-cells

The result is edited CAR T-cells that can be given to the patient so that they rapidly find and destroy T-cells in the body, including leukemic T-cells. If successful, the patient then receives a bone marrow transplant to restore their depleted immune system.

First patient going from strength-to-strength

Alyssa Tapley, 16 from Leicester, was the first patient in the world to receive a base-edited cell therapy and originally shared her story in 2022 when she was 13. At the time, she was cautiously optimistic with her leukaemia undetectable, but was under close monitoring. She has now been discharged to long-term follow up and is throwing herself into life with her friends and family

A family smile at the camera with a stadium roof in the background. They are all smiling and laughing and the boy at the back is wearing novelty glasses
Alyssa was diagnosed with T-cell leukaemia in May 2021, after a long period of what the family thought were colds, viruses and general tiredness. She did not respond to standard therapies - chemotherapy and a bone marrow transplant - and she was discussing the option of palliative care when the research opportunity was proposed.

Alyssa said: “I chose to take part in the research as I felt that, even if it didn’t work for me, it could help others. Years later, we know it worked and I’m doing really well. I’ve done all those things that you’re supposed to do when you’re a teenager.

“I’ve gone sailing, spent time away from home doing my Duke of Edinburgh Award but even just going to school is something I dreamed of when I was ill. I’m not taking anything for granted. Next on my list is learning to drive, but my ultimate goal is to become a research scientist and be part of the next big discovery that can help people like me.”

BE-CAR7 cells were manufactured as part of a long-standing research programme led by Professor Waseem Qasim at UCL Great Ormond Street Institute of Child Health, an NIHR Senior Investigator and Honorary Consultant at GOSH. Thanks to funding from NIHR, Wellcome, the Medical Research Council and GOSH Charity, Professor Qasim has been a pioneer in developing new gene therapy derived treatments, including using innovative genome editing techniques. The team is based at the Zayed Centre for Research into Rare Disease in Children, a partnership between GOSH and UCL. This state-of-the-art research institution was made possible thanks to the extraordinary philanthropic support of Her Highness Sheikha Fatima bint Mubarak. In 2014 Her Highness made a £60 million gift to GOSH Charity in honour of her late husband, Sheikh Zayed bin Sultan Al Nahyan.

The research team wish to thank Anthony Nolan and their volunteer blood and stem cell donors, and the patients and their families for participating in the research.

Learning from every treatment

NIHR Senior Investigator, Professor Waseem Qasim who led the research and is Professor of cell and gene therapy at UCL and Honorary consultant immunologist at GOSH said: “Many teams were involved across the hospital and everyone is delighted for patients clearing their disease, but at the same time, deeply mindful that outcomes were not as hoped in a minority of cases. These are intense and difficult treatments - patients and families have been generous in recognising the importance of learning as much as possible from each experience.”

Dr Rob Chiesa, Study investigator and Bone Marrow Transplant consultant at GOSH said: “Although most children with T-cell leukaemia will respond well to standard treatments, around 20% may not. It’s these patients who desperately need better options and this research provides hope for a better prognosis for everyone diagnosed with this rare but aggressive form of blood cancer.

“Seeing Alyssa go from strength-to-strength is incredible and a testament to her tenacity and the dedication of an array of small army of people at GOSH. Team working between bone marrow transplant, haematology, ward staff, teachers, play workers, physiotherapists, lab and research teams, among others, is essential for supporting our patients.”

Dr Deborah Yallop, consultant Haematologist at KCH 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) and our NIHR GOSH Biomedical Research Centre, 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.

As well as providing early funding to Professor Qasim to help pave the way for new cutting-edge treatment options, Great Ormond Street Hospital Charity (GOSH Charity) has now agreed to support treatment for another 10 patients as part of an extended cohort of T-ALL patients. Funding over £2m so that more children can access the clinical trial, this ties into GOSH Charity’s ongoing fundraising appeal to build a world-leading new Children's Cancer Centre at GOSH, which will help create an environment where pioneering research can thrive.