The recent International Consensus Classification differentiates two subgroups of Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL), t(9;22)/BCR::ABL1 B-ALL with lymphoid only or multilineage involvement. In the current project we plan to investigate the transcriptomic profiles as classifier and correlate those to genomic lesions of patients diagnosed with Ph+ ALL to find differentiating features between BCR::ABL1+ multilineage, BCR::ABL lymphoid ALL ALL-and CML in lymphoid blast crisis.