Clinical Study With Blinatumomab in Pediatric and Adolescent Patients With Relapsed/Refractory B-precursor Acute Lymphoblastic Leukemia

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer of the blood and bone marrow in which the bone marrow makes too many abnormal immature lymphocytes. Blinatumomab is a bispecific single-chain antibody construct designed to link B cells and T cells resulting in T cell activation and a cytotoxic T cell response against cluster of differentiation (CD)19 expressing cells. The purpose of this study is to investigate the pharmacokinetics (PK), pharmacodynamics (PD) and safety of escalating doses of blinatumomab in pediatric and adolescent patients with relapsed/refractory B-precursor ALL, to select a dose and to investigate the efficacy and safety of that dose of blinatumomab in the above-mentioned patient population. The phase 1 part of the study included the evaluation of four dose levels of blinatumomab with comprehensive PK/PD assessments and was separated in 2 parts: * Phase 1 dose evaluation/escalation part to define the recommended phase 2 dose of blinatumomab in patients aged 2 to 17 years * Phase 1 PK expansion part in patients aged \< 18 years to further assess PK/PD at the recommended phase 2 dose. In this part additional participants were enrolled to ensure that 6 patients in each of the 2 older age groups (2-6 and 7-17 years) were analyzed for PK before recruitment of infants \< 2 years of age began. In the phase 2 extension cohort (efficacy phase) of the study, eligible participants less than 18 years were enrolled according to a two-stage design and received blinatumomab at the recommended dose level (5/15 μg/m²/day). The study consisted of a screening period, a treatment period, and an End of Core Study visit 30 days after last dose of study medication. A treatment cycle consisted of a continuous intravenous (cIV) infusion over 4 weeks followed by a treatment-free interval of 2 weeks. Participants who achieved complete remission (CR) within 2 cycles of treatment could receive up to 3 additional consolidation cycles of blinatumomab. Instead of consolidation cycles with blinatumomab, participants could be withdrawn from blinatumomab treatment to receive chemotherapy or allogeneic HSCT as early as the first cycle, at the discretion of the investigator. After the last treatment cycle and End of Core Study visit, all participants were followed for efficacy and survival for up to 24 months after treatment start. Participants who suffered a hematological relapse of B-precursor ALL during their follow-up period (at least 3 months after completion of treatment) had the possibility for retreatment with blinatumomab.