Key Inclusion Criteria:

          1. Chinese patients age ≤25 years at the time of informed consent form (ICF) signature.

          2. Relapsed or refractory B-cell ALL

               1. 2nd or greater bone marrow (BM) relapse OR

               2. Any BM relapse after allogeneic SCT and must be ≥ 3 months from SCT at the time
                  of screening OR

               3. Primary refractory as defined as not achieving a CR after 2 cycles of a standard
                  first line chemotherapy regimen or chemorefractory as defined by not achieving a
                  CR after 1 cycle of standard chemotherapy for relapsed leukemia OR

               4. Subjects with Ph+ ALL are eligible if they are intolerant to or
                  relapsed/refractory after two lines of tyrosine kinase inhibitor (TKI) therapy,
                  or if TKI therapy is contraindicated OR

               5. Ineligible for allogeneic SCT because of: comorbid disease; other
                  contraindications to allogeneic SCT conditioning regimen; lack of suitable donor;
                  prior SCT; subject declines allogeneic SCT as a therapeutic option after
                  documented discussion about the role of SCT with a BMT physician not part of the
                  study team

          3. For relapsed patients, CD19 tumor expression demonstrated in bone marrow or peripheral
             blood by flow cytometry within 3 months of screening

          4. Bone marrow with ≥ 5% lymphoblasts on local morphologic assessment at screening

          5. Adequate performance status, cardiac, hepatic, renal and pulmonary function at
             screening

          6. Must meet the institutional criteria to undergo leukapheresis

          7. Once all other eligibility criteria are confirmed, must have a leukapheresis material
             of non-mobilized cells received and accepted for manufacturing.

        Key Exclusion Criteria:

          1. Isolated extra-medullary disease relapse

          2. Subjects with concomitant genetic syndromes associated with bone marrow failure
             states: such as subjects with Fanconi anemia, Kostmann syndrome, Shwachman syndrome or
             any other known bone marrow failure syndrome. Subjects with Down syndrome will not be
             excluded.

          3. Subjects with Burkitt's lymphoma/leukemia (i.e. subjects with mature B-cell ALL,
             leukemia with B-cell [sIg positive and kappa or lambda restricted positivity] ALL,
             with FAB L3 morphology and /or a MYC translocation)

          4. Prior anti-CD19 directed therapy, gene therapy or adoptive T cell therapy

          5. CNS involvement by ALL, defined as CNS-2 and CNS-3 disease per National Comprehensive
             Cancer Network guidelines NCCN 2018 v1

          6. Active neurological autoimmune or inflammatory disorders (e.g. Guillain-Barre
             syndrome)

          7. History or presence of clinically relevant CNS pathology, e.g., epilepsy, paresis,
             aphasia, stroke, severe brain injuries, cerebellar disease, organic brain syndrome, or
             psychosis.

          8. Investigational medicinal product within the last 30 days or five half-lives
             (whichever is longer) prior to screening NOTE: Investigational therapies must not be
             used at any time while on study until the first progression following tisagenlecleucel
             infusion.

          9. Previous or concurrent malignancy except for curatively treated non-melanoma skin
             cancers, in situ carcinoma (e.g. cervix, skin), and cancers in complete remission for
             at least 3 years and without evidence of recurrence