A Single-Arm Multicenter Phase II Study Preceded by Dose Evaluation to Investigate the Efficacy, Safety, and Tolerability of the BiTE® Antibody Blinatumomab (MT103) in Pediatric and Adolescent Patients With Relapsed/Refractory B-Precursor Acute Lymphoblastic Leukemia (ALL)

Inclusion Criteria:

- Morphologic evidence of B-precursor ALL with > 25% blasts in bone marrow (M3)at study
enrolment

- Age less than 18 years at enrollment

- Relapsed/refractory disease:

- Second or later bone marrow relapse,

- Any marrow relapse after allogeneic HSCT, or

- Refractory to other treatments: Patients in first relapse must have failed to
achieve a CR following full standard reinduction chemotherapy regimen of at
least 4 weeks duration.Patients who have not achieved a first remission must
have failed a full standard induction regimen

- Karnofsky performance status more than or equal to 50% for patients more than or
equal to 16 years and Lansky Performance Status (LPS) of more than or equal to 50%
for patients less than 16 years

- Organ function requirements: All patients must have adequate renal and liver
functions

Exclusion Criteria:

- Active acute or extensive chronic GvHD

- Immunosuppressive agents to prevent or treat GvHD within 2 weeks prior to
blinatumomab treatment

- Evidence for current CNS involvement by ALL (CNS 2, CNS 3) or testicular involvement
by ALL

- History of relevant CNS pathology or current relevant CNS pathology

- History of autoimmune disease with potential CNS involvement or current autoimmune
disease

- Any HSCT within 3 months prior to blinatumomab treatment

- Cancer chemotherapy within 2 weeks prior to blinatumomab treatment (except for
intrathecal chemotherapy and/or low dose maintenance therapy such as vinca alkaloids,
mercaptopurine, methotrexate, glucocorticoids)

- Chemotherapy related toxicities that haven't resolved to less than or equal to Grade
2

- Radiotherapy within 2 weeks prior to blinatumomab treatment

- Immunotherapy (e.g. rituximab, alemtuzumab) within 6 weeks prior to blinatumomab
treatment

- Any investigational product within 4 weeks prior to study entry

- Previous treatment with blinatumomab

- Active severe infection, any other concurrent disease or medical condition that could
be exacerbated by the treatment or would seriously complicate compliance with the
protocol

- Known infection with human immunodeficiency virus (HIV) or chronic infection with
hepatitis B virus (HbsAg positive) or hepatitis C virus (anti-HCV positive)