Blinatumomab After TCR Alpha Beta/CD19 Depleted HCT

This trial evaluates the ability of a biologically active therapy in blinatumomab, an anti-CD19/CD3 bispecific T-cell engager, to further reduce the risk of leukemia relapse following HCT to improve post-HCT outcomes. The investigators will also utilize an alpha-beta T-cell and B-cell depleted graft to reduce the risk of GVHD along with a reduced intensity conditioning regimen without the use of TBI in patients who are minimal residual disease (MRD) negative using high throughput sequencing (HTS) prior to HCT. For those patients who remain HTS-MRD positive, a myeloablative conditioning regimen will be utilized, also followed by blinatumomab. This multi-institutional pilot study will be limited to 25 (estimated 10-15 per stratum) evaluable children, adolescents and young adults with B-ALL, that have experienced a relapse or have high-risk disease.