Abstract
Relapsed T cell acute lymphoblastic leukaemia (T-ALL) has a very poor prognosis. A 24-year-old patient with relapsed high-risk T-ALL (PTEN gene deletion; NOTCH1 mutation), was treated with the NOTCH inhibitor CB-103. Within 1 week of starting CB-103, the bone marrow was free of T-ALL blast infiltration (MRD+) and successfully underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Sequential samples of ctDNA to monitor the disease after allo-HSCT showed a decrease of circulating Notch1 and PTEN alterations. This is the first T-ALL patient treated with CB-103. The observed clinical response encourages further exploration of CB-103 in ALL.