Inclusion Criteria for Collection Arm of the protocol:

        Age < 26 years, whose disease meets one of the following 3 criteria:

          -  VHR*

          -  Patients in 1st or subsequent marrow relapse (isolated or combined), at the time of
             relapse, during retrieval therapy, or after achievement of CR.

          -  Refractory disease *Definitions of VHR B-ALL include the following:

               -  NCI HR-ALL and age ≥ 13 years at diagnosis

               -  CNS-3 leukemia at diagnosis

               -  Day 29/End of Induction BM MRD > 0.01%

               -  Induction failure (M3 BM at Day 29/End of Induction)

               -  Hypodiploidy (n< 44 chromosomes and/or a DNA index < 0.81)

               -  t(9;22) ALL (Philadelphia Chromosome/Ph+ ALL)

               -  t(17;19) ALL or Ph-Like ALL

               -  MLL gene rearrangement

               -  IKZF1 deletions

               -  Intrachromosomal amplification of chromosome 21 (iAMP21) Please note patients
                  that only meet the criteria for collection/storage of PBMCs will need to be
                  reconsented prior to infusion of genetically modified T-cells.

        Inclusion Criteria for Treatment Arm of this protocol:

          -  Patients must have a history of relapsed/refractory CD19+ B-ALL involving the marrow
             to be eligible for infusion of modified T cells.

          -  Please note ≥5% blasts by morphology, FISH/cytogenetics, molecular translocation
             and/or flow cytometry constitutes a bone marrow relapse on this protocol. Patients
             must also fulfill one of the following criteria to be eligible for infusion of
             modified T cells:

               -  Second or greater (≥2) relapse

               -  Early first marrow relapse (1st CR <18 months)

               -  Intermediate/Late first marrow relapse (1st CR >18 months) with poor initial
                  response (≥5% blasts by morphology and/or flow cytometry) following reinduction
                  chemotherapy

               -  Refractory Disease

               -  Ineligible for HSCT as determined by the treating physician in consultation with
                  the BMT service

               -  Patient would not benefit from additional chemotherapy as determined by the
                  treating physician

          -  KPS or Lansky score ≥ 60

          -  Pulmonary function (measured prior to conditioning chemotherapy):

             o > 90% oxygen saturation on room air by pulse oximetry.

          -  Renal Function (measured prior to conditioning chemotherapy):

             o Serum creatinine ≤2.0mg/dL for patients over 18 years or ≤2.5 x institutional ULN
             for age

          -  Hepatic Function (measured prior to conditioning chemotherapy):

               -  AST ≤ 5 x the institutional ULN. Elevation secondary to leukemic involvement is
                  not an exclusion criterion. Leukemic involvement will be determined by the
                  presence of progressive relapse defined by escalating bone marrow or peripheral
                  blood leukemia blasts within the previous month and the absence of initiation of
                  know hepatotoxic medication (e.g. azoles).

               -  Total bilirubin ≤ 2.5 x the institutional ULN

        Exclusion Criteria for Collection of T cells/PBMCs:

          -  Karnofsky/Lansky performance status <60.

          -  Patients with any concurrent active malignancies as defined by malignancies requiring
             any therapy other than expectant observation

          -  Patients with active HIV, hepatitis B or hepatitis C infection.

          -  Females who are pregnant

        Exclusion Criteria for Treatment:

          -  Karnofsky/Lansky performance status <60.

          -  Patients with any concurrent active malignancies as defined by malignancies requiring
             any therapy other than expectant observation

          -  Patients will be excluded if they have isolated extra-medullary relapse of ALL

          -  Females who are pregnant.

          -  Patients with active (grade 2-4) acute graft versus host disease (GVHD), chronic GVHD
             or an overt autoimmune disease (e.g. hemolytic anemia) following allo-HSCT requiring
             glucocorticosteroid treatment (>0.5 mg/kg/day prednisone or its equivalent) as
             treatment.

          -  Active central nervous system (CNS) leukemia, as defined by unequivocal morphologic
             evidence of lymphoblasts in the cerebrospinal fluid (CSF) within 7 days of treatment
             or symptomatic CNS leukemia (i.e. cranial nerve palsies or other significant
             neurologic dysfunction) within 28 days of treatment. Prophylactic intrathecal
             medication is not a reason for exclusion.

             o If the LP is traumatic (containing RBCs) and cannot be repeated the Steinherz/Bleyer
             ratio will be used to determined unequivocal evidence of CSF leukemia at the
             discretion of the treating physician.

          -  Uncontrolled, symptomatic, intercurrent illness including but not limited to
             infection, psychiatric illness, or social situations that would limit compliance with
             study requirements or in the opinion of the treating investigator would pose an
             unacceptable risk to the subject.

          -  Prior neurologic toxicity to previous immunotherapy

          -  Preceding and/or ongoing organ dysfunction or other co-morbidity including but not
             limited to uncontrolled infection that would impair the patient's ability to endure
             known side effects of cytokine release syndrome or neurologic toxicity

          -  Recent prior therapy: Systemic chemotherapy less than 2 weeks prior to infusion or
             apheresis (6 weeks for clofarabine or nitrosoureas for apheresis) or radiation therapy
             less than or equal to 3 weeks prior to apheresis. Exceptions:

        oThere is no time restriction in regard to prior intrathecal chemotherapy provided there is
        complete recovery from any acute toxic effects of such.

        oSubjects receiving hydroxyurea or oral maintenance chemotherapy may be enrolled provided
        there has been no increase in dose for at least 2 weeks prior to starting apheresis or
        treatment.

        oSubjects receiving steroid therapy at physiologic replacement doses only are allowed
        provided there has been no increase in dose for at least 2 weeks prior to starting
        apheresis or treatment.

        oSubjects must have recovered from the acute side effects of their prior therapy, such that
        eligibility criteria are met. Cytopenias deemed to be disease-related and not
        therapy-related are exempt from this exclusion.

        •Rapidly progressive disease that in the estimation of the treating physician would
        compromise ability to complete study therapy.