Study of Efficacy and Safety of Reinfusion of Tisagenlecleucel in Pediatric and Young Adult Patients With Acute Lymphoblastic Leukemia (ALL)

Inclusion Criteria: * Signed informed consent must be obtained prior to participation in the study * Must have an additional dose of unexpired, commercial tisagenlecleucel available and prescribed by a physician in the course of medical practice * Age up to and including 25 years * Patients must have CD-19+ Leukemia * Patients who were previously treated with tisagenlecleucel and present with evidence of B-cell recovery as defined by: Peripheral blood (PB) absolute B lymphocyte count ≥ 50/µL, OR PB B lymphocyte ≥ 10% of the total lymphocytes Exclusion Criteria: * Prior gene therapy other than tisagenlecleucel * Prior adoptive T cell therapy other than tisagenlecleucel * Active CNS involvement by malignancy * Active or latent hepatitis B or active hepatitis C, or any uncontrolled infection at screening * HIV positive test within 8 weeks of screening