Both groups were also balanced with regard to ALL risk stratification according to the criteria of the German ALL study group [29, 30] with the study cohort comprising 8 patients with high risk and 9 patients with standard risk disease in the HER2/neu+ group, and 26 patients with high risk and 20 patients with standard risk ALL in the HER2/neu− group (p = 0.8). Here, ERBB2 is linked to acute lymphoblastic leukemia.