• Signed informed consent form must be obtained prior to any study procedure.

• Relapsed or refractory B-cell ALL:

‣ 2nd or greater relapse OR

⁃ Any marrow or extramedullary relapse after allogeneic HSCT and ≥ 6 months from SCT at infusion OR

⁃ Any marrow relapse after CAR-modified T cell therapy OR

⁃ Refractory disease defined as having not achieved a CR after \> 2 chemotherapy regimens OR

⁃ Patients with Ph+ ALL are eligible if they are intolerant to or have failed tyrosine kinase inhibitor therapy OR

⁃ Ineligible for allogeneic SCT because of:

• i. Comorbid disease ii. Other contraindications to allogeneic SCT conditioning regimen iii. Lack of suitable donor iv. Prior SCT v. Declines allogeneic SCT as a therapeutic option after documented discussion, with expected outcomes, about the role of SCT with a BMT physician not part of the study team g. Patients with CNS3 disease will be eligible if CNS disease is responsive to therapy (at infusion, must meet criteria in Section 5.2)

• Documentation of CD22 tumor expression in bone marrow, other tumor biopsy, CSF or peripheral blood by flow cytometry (or a recent marrow in the case of refractory disease). If the patient has received CD22-directed therapy (i.e., inotuzumab), then the marrow or other sample should be obtained after this therapy to show CD22 expression.

• Adequate organ function defined as:

• a. A serum creatinine based on age/gender as follows:

⁃ A serum creatinine based on age/gender as follows:

‣ Maximum Serum Creatinine (mg/dL) Age 1 to \< 2 years Male 0.6 Female 0.6 Age 2 to \< 6 years Male 0.8 Female 0.8 Age 6 to \< 10 years Male 1.0 Female 1.0 Age 10 to \< 13 years Male 1.2 Female 1.2 Age 13 to \< 16 years Male 1.5 Female 1.4 Age ≥ 16 years Male 1.7 Female 1.4

⁃ Adequate liver function

• i. ALT \< 500 U/L ii. Bilirubin \<3x upper limit of normal

• iii. ALT and/or bilirubin that exceed these ranges is acceptable if, in the opinion of the investigator (or by liver biopsy), the abnormalities are directly related to ALL infiltration of the liver

• c. Must have a minimum level of pulmonary reserve defined as ≤ Grade 1 dyspnea, pulse oxygen \> 92% on room air; DLCO \> 40% (corrected for anemia) if PFTs are clinically appropriate as determined by the treating investigator

• d. Left Ventricle Shortening Fraction (LVSF) ≥ 28% or Ejection Fraction (LVEF) ≥ 40% confirmed by ECHO/MUGA; in cases where quantitative assessment of LVEF is not possible, a statement by the cardiologist that the ECHO shows qualitatively normal ventricular function will suffice.

• Evidence of disease by standard morphologic or by MRD criteria. If the results of a historical biopsy (obtained at the time of the patient's most recent relapse) are available, this does not need to be repeated at screening.

• Age 1-29 years.

• Adequate performance status (Lansky or Karnofsky score ≥50).

• Subjects of reproductive potential must agree to use acceptable birth control methods.