Efficacy and toxicity of high-risk therapy of the Dutch Childhood Oncology Group in childhood acute lymphoblastic leukemia.

The high survival with HR blocks seems favorable compared with other studies. However, the limit of treatment intensification might have been reached as the number of patients dying from leukemia relapse is about equal as the number of patients dying from toxicity. Patients with negative or low MRD levels during HR blocks have lower relapse rates.