Inclusion Criteria:

- Patients with Ph-negative B-precursor ALL, with any of the following:

- relapsed or refractory with first remission duration less than or equal to 12 months
in first salvage or

- relapsed or refractory after first salvage therapy or

- relapsed or refractory within 12 months of allogeneic HSCT

- 10% or more blasts in bone marrow

- In case of clinical signs of additional extramedullary disease: measurable disease

- ECOG performance status ≤ 2

- Age ≥ 18 years

Exclusion Criteria:

- Patients with Ph-positive ALL

- Patients with Burkitt's Leukemia according to WHO classification

- History or presence of clinically relevant CNS pathology

- Active ALL in the CNS or testes

- Current autoimmune disease or history of autoimmune disease with potential CNS
involvement

- Autologous HSCT within six weeks prior to start of blinatumomab treatment

- Allogeneic HSCT within three months prior to start of blinatumomab treatment

- Any active acute GvHD, or active chronic GvHD Grade 2 - 4

- Any systemic therapy against GvHD within two weeks prior to start of blinatumomab
treatment

- Cancer chemotherapy within two weeks prior to start of blinatumomab treatment

- Radiotherapy within two weeks prior to start of blinatumomab treatment

- Immunotherapy (e.g., rituximab) within four weeks prior to start of blinatumomab
treat-ment

- Any investigational anti-leukemic product within four weeks prior to start of
blinatumomab treatment

- Treatment with any other IMP after signature of informed consent

- Eligibility for allogeneic HSCT at the time of enrollment

- Known hypersensitivity to immunoglobulins or to any other component of the IMP
formulation

- Abnormal laboratory values indicative of inadequate renal or liver function

- History of malignancy requiring treatment other than ALL within five years prior to
start of blinatumomab treatment with the exception of basal cell or squamous cell
carcinoma of the skin, or carcinoma "in situ" of the cervix

- Any concurrent disease or medical condition that is deemed to interfere with the
conduct of the study

- Infection with HIV or chronic infection with hepatitis B virus or hepatitis C virus

- Pregnant or nursing women

- Women of childbearing potential not willing to use an effective form of
contraception. Male patients not willing to ensure not to beget a child

- Previous treatment with blinatumomab