Retrospective analysis of survival in adult MRD positive Acute Lymphoblastic Leukemia patients

-patients with Philadelphia-negative B-Precursor Acute Lyphmoblastic Leukemia in complete hematological remission defined as less than 5% blasts in bone marrow after at least 3 intensive chemotherapy blocks (i.e. any standard or investigational regimen according to adult protocols as long as 3 age appropriate chemotherapy blocks were given, this also includes relapse treatment - detection of minimal residual disease (molecular failure or molecular relapse) at a level of greater than or equal to 10*(-4) by PCR or greater than or equal to 10*(-3) by flow cytometry at a reference lab - Age 15 or greater at time of initial diagnosis with acute lymphoblastic leukemia. For patients aged 15-17 treatment according to adult protocols is required - Initial diagnosis in the year 2000 or later - History of acute lymphoblastic leukemia treatment (including response to first therapy, number of prior relapses) is available - Relapse status and disease follow up after timepoint of minimal residual disease detection is available

- Patients with extramedullary disease at timepoint of minimal residual disease detection - Use of Blinatumomab within 18 months of minimal residual disease detection - Allogeneic hematopoietic stem cell transplantation prior to minimal residual disease detection at the required level