Inclusion Criteria:

          1. Patients with CD19 positive B-precursor ALL in complete hematological remission
             defined as less than 5% blasts in bone marrow after at least three intense
             chemotherapy blocks (e.g., GMALL induction I-II/consolidation I).

          2. Presence of minimal residual disease (MRD) after an interval of at least 8 days from
             last systemic chemo-therapy

               -  at a level of ≥10-4 - <10-3 (molecular failure or molecular relapse) in an assay
                  with a minimum sensitivity of 10-4 documented after an interval of at least 2
                  weeks from last systemic chemotherapy OR

               -  at levels below 10-4 documented after an interval of at least 2 weeks from last
                  systemic chemotherapy:

                    -  Positive <10-4, non quantifiable (MolNE1) OR

                    -  Positive <10-4 (MolNE2) OR

               -  Presence of minimal residual disease (MRD), non quantifiable (MolNE3).

          3. For evaluation of MRD patients must have at least one molecular marker based on
             individual rearrangements of immunoglobulin, TCR-genes or other suitable genes
             evaluated by the reference laboratory of the trial

          4. Bone marrow function as defined below:

               -  ANC (Neutrophils) >= 1,000/µL

               -  Platelets >= 50,000/µL (transfusion permitted)

               -  HB level >= 9g/dl (transfusion permitted)

          5. Renal and hepatic function as defined below:

               -  AST (GOT), ALT (GPT), and AP < 5 x upper limit of normal (ULN)

               -  Total bilirubin < 1.5 x ULN (unless related to Gilbert's Meulengracht disease)

               -  Creatinine < 1.5x ULN

               -  Creatinine clearance >= 60 mL/min (e.g. calculated according Cockroft&Gault)

          6. Negative HIV test, negative hepatitis B (HbsAg) and hepatitis C virus (anti-HCV) test

          7. Negative pregnancy test in women of childbearing potential

          8. ECOG Performance Status 0 or 1

          9. Age >=18 years

         10. Ability to understand and willingness to sign a written informed consent

         11. Signed and dated written informed consent is available

         12. Participation in the registry of the German Multicenter Study Group for Adult ALL
             (GMALL)

        Exclusion Criteria:

          1. Ph/BCR-ABL positive ALL

          2. Presence of circulating blasts or current extramedullary involvement by ALL

          3. History or presence of clinically relevant CNS pathology (e.g. seizure, paresis,
             aphasia, cerebrovascular ischemia/hemorrhage, severe brain injuries, dementia,
             Parkinson's disease, cerebellar disease, organic brain syndrome or psychosis)

          4. Current detection of ALL blast cells in cerebro-spinal fluid

          5. History of or active relevant autoimmune disease

          6. Systemic cancer chemotherapy within 2 weeks prior to study treatment (except for
             intrathecal prophylaxis)

          7. Radiotherapy within 4 weeks prior to study treatment

          8. Live vaccination within 2 weeks before the start of study treatment

          9. Autologous hematopoietic stem cell transplantation (SCT) within six weeks prior to
             study treatment

         10. Allogeneic SCT within 12 weeks before the start of study treatment

         11. Any active acute Graft-versus-Host Disease (GvHD), grade 2-4 according to the
             Glucksberg criteria or active chronic GvHD requiring systemic treatment

         12. Any systemic therapy against GvHD within 2 weeks before start of study treatment

         13. Therapy with monoclonal antibodies (rituximab, alemtuzumab) within 4 weeks prior to
             study treatment

         14. Treatment with any investigational product within four weeks prior to study treatment

         15. Previous treatment with blinatumomab or other anti-CD19-therapy

         16. Known hypersensitivity to immunoglobulins or to any other component of the study drug
             formulation

         17. History of malignancy other than ALL diagnosed within 5 years prior to start of
             protocol-specified therapy with the exception of:

               -  Adequately treated non-melanoma skin cancer or lentigo maligna without evidence
                  of disease

               -  Adequately treated cervical carcinoma in situ without evidence of disease

               -  Adequately treated breast ductal carcinoma in situ without evidence of disease

               -  Prostatic intraepithelial neoplasia without evidence of prostate cancer

         18. Active infection, any other concurrent disease or medical condition that are deemed to
             interfere with the conduct of the study as judged by the investigator

         19. Nursing women

         20. Woman of childbearing potential and is not willing to use 2 highly effective methods
             of contraception while receiving study treatment and for an additional 3 months after
             the last dose of study treatment.

         21. Male who has a female partner of childbearing potential, and is not willing to use 2
             highly effective forms of contraception while receiving study treatment and for at
             least an additional 3 months after the last dose of study treatment