In 2004, during study ALL-BFM 2000, the indication criteria for HSCT in CR1 were adapted to the ALL-SCT-BFM-2003 trial, thus excluding patients with an MRD load of <10−4 at EOC except for KMT2A-AFF1 positive leukemias (22). Here, AFF1 is linked to acute lymphoblastic leukemia.