Methods
In the multicenter-trial CoALL08-09, an additional treatment element consisting of the rarely used chemotherapeutic agent amsacrine combined with etoposide and methylprednisolone (AEP) (amsacrine 2 x 100 mg/m2, etoposide 2 x 500 mg/m2 and methylprednisolone 4 x 1000 mg/m2) was implemented into the first-line treatment of pediatric patients with a poor treatment response at the end of induction (EOI) measured by minimal residual disease (MRD). These patients were stratified into a high-risk intensified arm (HR-I) including an AEP element at the end of consolidation. Patients with induction failure (IF), i.e. lack of cytomorphological remission EOI, were eligible for hematopoietic stem cell transplantation (HSCT) after remission had been reached later on. These patients received AEP as a part of their MRD-guided bridging-to-transplant treatment.