“…Treatment stratification and protocols used in trials BFM-A 81, ALL A 84, BFM-A 86, and BFM-A 90 have been published in detail elsewhere [9,12,24,25]. In brief, in trials BFM-A 81 and ALL A 84, treatment stratification was solely based on a risk factor (RF), which was calculated from the initial peripheral blast cell count and size of liver and spleen [24,25]. In trials BFM-A 86 and 90, treatment stratification was based on the RF, the prednisone response on day 8 of therapy, the BM response on day 33, translocation t(9;22), initial central nervous system (CNS) disease, and the blast cell immunophenotype [9,12].…”