To learn about the safety of post-HSCT two dose Inotuzumab Ozogamicin to participants with high risk B cell acute lymphoblastic leukemia(B-ALL). Also, to learn if giving Inotuzumab Ozogamicin to post-HSCT patients with high-risk B- ALL can help to reduce relapse and prolong disease free survival and overall survival.

This is a Phase II study of inotuzumab ozogamicin for the treatment of patients who underwent transplantation for ALL and have a high risk of relapse. Participants will receive study treatment two doses until relapse of disease, unacceptable toxicity, or death, whichever occurs first Primary Objective

• To assess the efficacy of inotuzumab ozogamicin as measured by disease free survival (DFS) at one year.

Secondary Objective(s)

• To evaluate relapse rate, nonrelapse mortality (NRM), relapse, relapse-related mortality and overall survival (OS) at 1 year.
• To determine safety profile of inotuzumab ozogamicin after transplant including the incidence of hematological toxicity, secondary graft failure and other adverse event(AE)/severe adverse event(SAEs)

Inclusion Criteria:

• Diagnosis of CD22-positive Acute Lymphoblastic Leukemia

• Patients who underwent an allogeneic hematopoietic stem cell transplantation(HSCT) from any donor source or auto-HSCT for acute lymphocytic leukemia

• Patients who are after T+60 after transplantation

• Patients who have/are either:

  • High risk B-ALL: (1) high white blood cell(WBC) count when newly diagnosed, (2) Poor risk group according to NCCN guideline 2021 of Acute Lymphoblastic
  • Leukemia
  • Relapsed or refractory to at least 1 line of treatment
  • Minimal residual disease(MRD) positive before HSCT, including flow cytometry and cytogenetic test

• Patients who have > 99% donor chimerism after allogeneic transplantation.

• Eastern Cooperative Oncology Group(ECOG) Performance status ≤ 2

• Participants must have ANC > 1,000/µL for 3 days and platelet transfusion independence as defined as a platelet count > 50,000/µL for 7 days.

• ≥ 18 years old, including male and female

• Participants must have the ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

• Patients with evidence of disease progression prior to enrollment

• Persistent prior treatment toxicities Grade 2 and above according to NCI CTCAE Version 4.03 (with the exception for alopecia, neuropathy, etc.)

• Patients with inadequate organ function and can't tolerate the study treatment determined by investigator as defined by:

  • Severe renal deficiency, with creatinine clearance < 50ml/min
  • Severe hepatic deficiency
  • Bilirubin, aspartate aminotransferase(AST), and/or ALT(ALT) > 2X institutional upper limit of normal
  • Severe cardiac or pulmonary deficiency

• Graft-versus-host disease(GVHD) grade III or IV (for patients with a prior allogeneic transplant).

• Active acute or chronic GVHD of the liver (for patients with a prior allogeneic transplant)

• History of veno-occlusive disease(VOD)

• Second active malignancy, other than non-melanoma skin cancer or carcinoma in situ (e.g. cervix, bladder, breast)

• Patients with uncontrolled inter-current illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.

• Serologic status reflecting active hepatitis B or C infection. Patients that are positive for hepatitis B core antibody, hepatitis B surface antigen (HBsAg), or hepatitis C antibody must have a negative polymerase chain reaction (PCR) prior to enrollment. (PCR positive patients will be excluded.)

• Any condition that would, in the investigator's judgment, interfere with full participation in the study, including administration of study drug and attending required study visits; pose a significant risk to the participant; or interfere with interpretation of study data.

• Known allergies, hypersensitivity, or intolerance to any of the study medications, excipients, or similar compounds