van Binsbergen AL, de Haas V, van der Velden VHJ, et al. - The high survival conferred by high-risk (HR) blocks in acute lymphoblastic leukemia (ALL) appears favorable relative to other studies. Number of deaths due to leukemia relapse was about equal to the number of deaths due to toxicity, therefore, the limit of treatment intensification might have been reached.

• A total of 107 children with ALL and HR features received one induction and consolidation course followed by three HR chemotherapy blocks, thereafter either stem cell transplantation or further chemotherapy.

• At 5 years, event-free survival was 72.8%, and cumulative incidence of relapse was 13.0%.

• Lower relapse rates were evident in patients with negative or low minimal residual disease levels during HR blocks.

• Death due to toxicity occurred in 11.2% of patients.