MB-CART19.1 in Relapsed/Refractory Acute Lymphoblastic Leukemia

Inclusion Criteria: * Age ≥ 1 year as long as if deemed fit by treating investigator * CD19 expression must be detected (≥20%) on the malignant cells by flow cytometry. * Patients with relapsed or refractory disease with \>5% blasts in the bone marrow after at least one frontline and one salvage chemotherapy regimen. For patients with Philadelphia-positive disease, a second generation or higher TKI must have been utilized in one of the treatment lines. * Patients who have relapsed post alloSCT at least 100 days post-transplant, with no evidence of active graft vs host disease, and no longer taking immunosuppressive agents for at least 30 days prior to enrollment. * Estimated life expectancy \> 12 weeks * Karnofsky or Lansky (age dependent) performance score ≥ 60 * Patients and/or parents must give their written informed consent/assent. * CNS and/or testicular involvement are allowed, only if cleared and in the presence of systemic involvement. Exclusion Criteria: * Rapidly progressive, uncontrolled disease as assessed by the treating physician and/or principal investigator. * Persistent extramedullary disease. * Isolated CNS and/or testicular disease. * Current autoimmune disease, or history of autoimmune disease with potential CNS involvement * Active hepatitis B, C or HIV * Active clinically significant CNS dysfunction (including but not limited to uncontrolled seizure disorders, cerebrovascular ischemia or hemorrhage, dementia, paralysis) * History of an additional malignancy (≤ 3 years) other than non-melanoma skin cancer or carcinoma in situ. * Pulmonary function: Patients with pre-existing severe lung disease (FEV1 or FVC \< 65%) or an oxygen requirement of \>28% O2 FiO2 or active pulmonary infection. * Cardiac function: Left ventricular ejection fraction \<50% by echocardiography * Renal function: Creatinine clearance \<50 mL/min/1.73 m2 * Liver function: patients with serum bilirubin ≥3 times upper limit of or AST or ALT \> 5 times upper limit of normal, unless due to leukemic liver infiltration as determined by the investigators. * Pregnant or breast-feeding females * Medications: systemic chemotherapies, corticosteroids with the exception of physiologic replacement dosing (\<0.5 mg/kg/day of methylprednicone), tyrosine kinase inhibitors (TKI) within 7 days prior to leukapheresis, Fludarabine/clofarabine or immunosuppressive drugs and antibodies (e.g. rituximab, blinatumomab) or investigational drugs or donor lymphocyte