Inclusion Criteria:

          -  Patients with B-lineage acute lymphocytic leukemia (ALL) in hematologic complete
             remission (CR) with molecular failure (i.e., had never achieved an MRD-negativity
             status before blinatumomab) or had a molecular relapse (i.e., became MRD positive
             after having been MRD negative) starting at any time point after 3 months of frontline
             therapy; molecular disease or minimal residual disease is defined by a value of at
             least of 1 x 10^-4 (0.01%) by multicolor flow cytometry and/or by next generation
             sequencing (NGS)

          -  Patients with B-lineage ALL in hematologic complete remission (CR) with molecular
             failure (i.e., had never achieved an MRD-negativity status before blinatumomab) or had
             a molecular relapse (i.e., became MRD positive after having been MRD negative)
             starting at any time point after 3 months of frontline therapy; molecular disease or
             minimal residual disease is defined by a value of at least of 1 x 10-4 (0.01%) by
             multicolor flow cytometry and/or by next generation sequencing (NGS)

          -  Performance status of 0, 1, or 2

          -  Creatinine clearance >= 30 ml/minute

          -  Bilirubin less than or equal to 3.0 mg/dL

          -  No active or co-existing malignancy with life expectancy less than 12 months

          -  Patients with Philadelphia chromosome positive (Ph+) ALL can be enrolled in CR1 or CR2
             and beyond; a tyrosine kinase inhibitor (TKI) will be added at the discretion of the
             treating physician; MRD for these patients will be defined by PCR of 0.1% and above
             (International Scale)

        Exclusion Criteria:

          -  Pregnant or nursing women

          -  Known to be human immunodeficiency virus positive (HIV+)

          -  Active and uncontrolled disease/infection as judged by the treating physician

          -  Unable or unwilling to sign the consent form

          -  Active central nervous system (CNS) or extramedullary disease

          -  Monoclonal antibodies therapy within 2 weeks before study entry

          -  Radiotherapy and cancer chemotherapy (except for intrathecal prophylaxis and/or
             low-dose maintenance therapy such as vinca alkaloids, mercaptopurine, methotrexate,
             steroids) or any investigational drug within 2 weeks before study entry