New insight into when CAR T is effective against childhood leukaemia

Scientists and clinicians at UCL and Great Ormond Street Hospital (GOSH) studying the effectiveness of CAR T-cell therapies in children with leukaemia, have discovered a small sub-set of T-cells that are likely to play a key role in whether the treatment is successful. Researchers say 'stem cell memory T-cells' appear critical in both destroying the cancer at the outset and for long term immune surveillance and exploiting this quality could improve the design and performance of CAR T therapies. Explaining the study, published in  Nature Cancer , lead author Dr Luca Biasco (UCL Great Ormond Street Institute of Child Health), said: "During clinical trials we have seen some very encouraging results in young patients with leukaemia, however it's still not clear why CAR T-cells continue to be present in the long-term for some patients, stopping the cancer from returning, while others remain at a high risk of relapse. "To ensure that a leukaemia treatment works any CAR T-cell therapy must have a prolonged effect on the way that the body recognises and removes cancer cells. In this study we tried to find the origin and nature of the T-cells that control these long-term responses." In CAR T therapy, immune cells (T-cells) are genetically engineered to contain a molecule called a chimeric antigen receptor (CAR) on their surface which can specifically recognise cancerous cells. Researchers assessed the CAR T-cells of patients involved in the CARPALL Phase I Study, which used a new CAR molecule known as CAT-19 developed between UCL Cancer Institute and UCL Great Ormond Street Institute of Child Health, for treatment in children with acute lymphoblastic leukaemia (ALL).