Who can participate? Patients aged 6 months to 16 years with relapsed/refractory T cell leukaemia ahead of a planned bone marrow transplant~What does the study involve? Patients will undergo careful screening to confirm that this treatment is adequate for them. Chemotherapy will be given prior to BE CAR-7 infusion to improve the ability of T-cells to establish and grow. Patients will then receive a single infusion of the BE CAR-7 cells and will be closely monitored in hospital. Patients are expected to be in hospital for 4-6 weeks for the BE CAR-7 treatment and the transplant will be scheduled 2-4 weeks after the end of BE CAR7 if leukaemia cells are no longer detectable. Patients will be monitored on the study for 1 year after transplant and then long term in routine clinics.~What are the possible benefits and risks of participating? Taking part in the study of testing 'ready-made' CAR T cells could help reduce the amount of disease and get the patient into remission before a bone marrow transplant. Leukaemia is less likely to come back after a bone marrow transplant if levels in the bone marrow are undetectable. The ready-made CAR T cells are being used to try and improve the chances of successful transplantation. Side effects may include low blood cell counts, infections, cytokine storm (severe immune reaction), graft versus host disease (where the donated cells attack the body) and other complications.
T-cell leukaemia is an uncommon type of blood cell cancer that affects white blood cells (T cells). This phase I clinical trial will treat children aged 6 months up to 16 years with T cell leukaemia which has come back (relapsed) after chemotherapy or is not responding to chemotherapy (refractory). The cell therapy is made from white blood cells (T cells) collected from a healthy donor and changed so they can kill other T cells, including leukaemia cells. These 'ready-made' CAR T cells have been made using a new technique called CRISPR base editing to modify them DNA code and have been given the name BE CAR-7. This technique allows them to work after chemotherapy and also disarms them to prevent effects against normal cells. The main aim of this study is to assess the safety of the BE CAR-7 treatment and to see if ready-made CAR T cells can eradicate T cell leukaemia ahead of a planned bone marrow transplant.