Study of UCART19 in Pediatric Patients With Relapsed/Refractory B Acute Lymphoblastic Leukemia

Inclusion Criteria: * Patient with relapsed or refractory CD19-positive B-acute lymphoblastic leukaemia (B-ALL) who have exhausted alternative treatment options. * Estimated life expectancy ≥ 12 weeks * Lansky (age \< 16 years at the time of assent/consent) or Karnofsky (age ≥ 16 years at time of assent/consent) performance status ≥ 50 Exclusion Criteria: * Burkitt leukemia * CD19-negative B-cell leukemia * Active Central Nervous System (CNS) leukemia * Active acute or chronic Graft-versus-Host Disease (GvHD) requiring systemic use therapy within 4 weeks before UCART19 infusion * Patients with autoimmune disease requiring systemic immunosuppression therapy that cannot be stopped * History of CRS grade 4 related to previous CAR T cell therapy * Contraindication to Alemtuzumab administration