Study of Blinatumomab Administration in Chinese Pediatric Participants with Relapsed/Refractory B precursor Acute Lymphoblastic Leukemia (R/R B-ALL)

- Participant’s parent or legally authorized representative has provided informed consent when the participant is legally too young to provide informed consent and the participant has provided written assent based on local regulations and/or guidelines prior to any study-specific activities/procedures being initiated - Pediatric participants aged > 1 month and < 18 years at the time of informed consent - Relapsed or/refractory precursor B-cell acute lymphoblastic leukemia (ALL) disease, defined as ≥5% bone marrow blasts with at least one of the following: - Second or later bone marrow relapse; - Any marrow relapse after allogeneic hematopoietic stem cell transplant (alloHSCT); - Refractory to other treatments: - For participants in first relapse: failure to achieve a complete remission (CR) following a full standard reinduction chemotherapy regimen - For participants who have not achieved a first remission, failure to achieve remission following a full standard induction regimen - Karnofsky performance status ≥ 50% for participants ≥ 16 years - Lansky performance status ≥ 50% for participants < 16 years

- Evidence of current central nervous system (CNS) involvement by ALL. Participants with CNS disease at the time of relapse are eligible if CNS is successfully treated prior to enrollment. Other Medical Conditions - Clinically relevant CNS pathology requiring treatment (eg, unstable epilepsy). - Isolated extramedullary (EM) disease. - Active malignancy other than ALL. - Burkitt’s leukemia according to the World Health Organization (WHO) 2016 criteria. - Abnormal renal or hepatic function at screening as defined below: - Abnormal serum creatinine based on age/gender as described by Threshold Creatinine Values - Direct bilirubin > 1.5 mg/dl (25.6 μmol/L) at screening (unless related to Gilbert’s or Meulengracht disease). - Symptoms and/or clinical signs and/or radiological and/or sonographic signs that indicate an acute or uncontrolled chronic 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 (hepatitis B surface antigen [HBsAg] positive) or hepatitis C virus (HCV) (anti-HCV positive). - Known hypersensitivity to blinatumomab or any of the products or components of the blinatumomab formulation. Prior/Concomitant Therapy - AlloHSCT within 12 weeks prior to start of protocol-specified therapy. - Active acute or chronic Graft-versus-Host-Disease (GvHD) requiring systemic treatment with immunosuppressive medication. - Radiotherapy within 2 weeks prior to start of protocol-specified therapy. - Immunotherapy (eg, rituximab) within 4 weeks prior to start of protocol-specified therapy. Prior failed cluster of differentiation 19 (CD19) directed therapy such as prior blinatumomab or CD19 chimeric antigen receptor T cells (CAR T cell) will be allowed (with demonstrated continued CD19+ expression) if treatment ended > 4 weeks prior to start of protocol-specified therapy. - Cancer chemotherapy within 2 weeks before the start of protocol-specified therapy. With the exception of intrathecal chemotherapy and/or low dose maintenance therapy for example vinca alkaloids, mercaptopurine, methotrexate, or hydroxyurea or pre-phase chemotherapy and/or dexamethasone. Any low dose chemotherapy as stated above must be discontinued before starting pre-phase. Prior/Concurrent Clinical Study Experience - Currently receiving treatment in another investigational device or drug study, or less than 4 weeks since ending treatment on another investigational device or drug study(ies). Other investigational procedures while participating in this study are excluded. Other Exclusions - Female participants of childbearing potential with a positive pregnancy test assessed at Screening by a highly sensitive urine or serum pregnancy test. - Female participants who are breastfeeding or who plan to breastfeed while on study through 12 months after the last dose of protocol-required treatment with highest teratogenic risk. -Female participants of childbearing potential unwilling to use protocol-specified method of contraception during treatment and for an additional 12 months after the last dose of protocol-required treatment with highest teratogenic risk. - Male participants with a female partner of childbearing potential who are unwilling to practice sexual abstinence (refrain from heterosexual intercourse) or use contraception during treatment and for an additional 6 months after the last dose of protocol-required therapy with highest teratogenic risk. - Participant likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures to the best of the participant and investigator’s knowledge. - Female participants planning to become pregnant while on study through 12 months after the last dose of protocol-required treatment with highest teratogenic risk. - Male participants unwilling to abstain from donating sperm during treatment and for an additional 6 months after the last dose of protocol-required treatment with highest teratogenic risk.