Inclusion Criteria for Autologous Apheresis:
* Age ≤ 21 years old
* CD19+ ALL with any of the following:
* Minimal Residual Disease (MRD) ≥ 1% at end of up-front induction therapy
* Hypodiploid (\< 44 chromosomes or \< 0.95 DNA index) CD19+ ALL with detectable disease at the end of up-front induction therapy
* Increase in disease burden any time after the completion of up-front induction therapy
* Primary refractory disease despite at least 2 cycles of an intensive chemotherapy regimen designed to induce remission
* Refractory disease despite salvage therapy
* 1st or greater relapse
* Estimated life expectancy of \> 12 weeks
* Karnofsky or Lansky (age-dependent) performance score ≥ 50
* Patients with a history of prior allogeneic hematopoietic cell transplantation \[HCT\] must be clinically recovered from prior HCT therapy, have no evidence of active GVHD and have not received a donor lymphocyte infusion (DLI) within the 28 days prior to apheresis
* For females of child bearing age:
* Not lactating with intent to breastfeed
* Not pregnant with negative serum pregnancy test within 7 days prior to enrollment
Exclusion Criteria for Autologous Apheresis:
* Known primary immunodeficiency
* History of HIV infection
* Severe intercurrent bacterial, viral or fungal infection
* History of hypersensitivity reactions to murine protein-containing products
Eligibility Criteria for Manufacturing SJCAR19:
* CD19+ ALL with any of the following:
* Primary refractory disease despite at least 2 cycles of an intensive chemotherapy regimen designed to induce remission
* Refractory disease despite salvage therapy
* 2nd or greater relapse
* Any relapse after allogeneic hematopoietic cell transplantation
* 1st relapse if patient requires an allogeneic HCT as part of standard of care relapse therapy, but is found to be ineligible and/or unsuitable for HCT
* Age: ≤ 21 years of age
* Karnofsky or Lansky (age-dependent) performance score ≥ 50
* Estimated life expectancy of \> 12 weeks
* Meets eligibility criteria to undergo autologous apheresis, or have previously undergone autologous apheresis
Inclusion Criteria for Treatment with SJCAR19:
* CD19+ ALL with any of the following:
* Primary refractory disease despite at least 2 cycles of an intensive chemotherapy regimen designed to induce remission
* Refractory disease despite salvage therapy
* 2nd or greater relapse
* Any relapse after allogeneic hematopoietic cell transplantation
* 1st relapse if patient requires an allogeneic HCT as part of standard of care relapse therapy, but is found to be ineligible and/or unsuitable for HCT for any of the following reasons:
* Patients that do not have an available allogeneic donor (defined as at least a 7/8 HLA-matched related/unrelated donor, 5/6 HLA-matched umbilical cord donor, or 3/6 HLA-matched haploidentical donor)
* Patients with refractory leukemia, for which allogeneic transplant is known to be less effective in the B-ALL population, and
* Patients who are unable to receive myeloablative total body irradiation (TBI), which is included in standard transplant regimens for patients with B - ALL.
* Detectable disease
* Age: ≤ 21 years of age
* Estimated life expectancy of \> 8 weeks
* Prior to planned SJCAR19 infusion, patients with a history of prior allogeneic HCT must be at least 3 months from HCT, have no evidence of active GVHD and have not received a donor lymphocyte infusion (DLI) within the 28 days prior to planned infusion
* Adequate cardiac function defined as left ventricular ejection fraction \> 40%, or shortening fraction ≥ 25%
* EKG without evidence of clinically significant arrhythmia
* Adequate renal function defined as creatinine clearance or radioisotope GFR ≥50 ml/min/1.73m2 (GFR ≥40 ml/min/1.73m2 if \< 2 years of age)
* Adequate pulmonary function defined as forced vital capacity (FVC) ≥ 50% of predicted value; or pulse oximetry ≥ 92% on room air if patient is unable to perform pulmonary function testing
* Karnofsky or Lansky (age-dependent) performance score ≥ 50
* Total Bilirubin ≤ 3 times the upper limit of normal for age, except in subjects with Gilbert's syndrome
* Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤ 5 times the upper limit of normal for age
* Hemoglobin \> 8 g/dl (can be transfused)
* Platelet count \> 20,000/μL (can be transfused)
* Has recovered from all NCI CTAE grade III-IV, non-hematologic acute toxicities from prior therapy
* For females of child bearing age:
* Not lactating with intent to breastfeed
* Not pregnant with negative serum pregnancy test within 7 days prior to enrollment
* If sexually active, agreement to use birth control until 6 months after T-cell infusion. Male partners should use a condom
* Available SJCAR19 product with ≥ 15% expression of the CD19-CAR, and killing of CD19+ targets ≥ 20% in an in vitro cytotoxicity assay
* Agreement to participate in long-term follow-up on protocol NCT00695279
Exclusion Criteria for Treatment with SJCAR19:
* CNS-3 disease with or without neurologic changes
* CNS-1/CNS-2 disease with neurologic changes
* Known primary immunodeficiency
* History of HIV infection
* Evidence of active, uncontrolled neurologic disease
* Severe, uncontrolled bacterial, viral or fungal infection
* History of hypersensitivity reactions to murine protein-containing products
* Receiving systemic steroids therapy exceeding the equivalent of 0.5 mg/ kg/day of methylprednisolone, in the 7 days prior to CAR T-cell infusion
* Receiving systemic immunosuppressive therapy in the 14 days prior to CAR T-cell infusion
* Receiving intrathecal chemotherapy in the 7 days prior to CAR T-cell infusion
