As part of postremission consolidative therapy, the decision to proceed with hematopoietic stem cell transplantation is a recommendable regimen in ALL therapy. However, The recurrence rate is high after transplantation. Minimal Residual Disease (MRD) is an important factor affecting the effect of HSCT. The hematologic recurrence rate of MRD-positive patients with adult ALL is high.

MRD- is associated with better prognosis. Therefore, maintaining MRD- after transplantation is necessary for long-term survival. The purpose of this study is to explore the efficacy and safety of Inotuzumab Ozogamicin in the treatment of minimal residual disease recurrence after HSCT of ALL patients.

As part of postremission consolidative therapy, the decision to proceed with hematopoietic stem cell transplantation is a recommendable regimen in ALL therapy. However, The recurrence rate is high after transplantation. Minimal Residual Disease (MRD) is an important factor affecting the effect of HSCT. The hematologic recurrence rate of MRD-positive patients with adult ALL is high.

MRD- is associated with better prognosis. Therefore, maintaining MRD- after transplantation is necessary for long-term survival. INO-VATE confirmed that Inotuzumab Ozogamicin can be used to achieve high remission (CR/CRi) and MRD-negative rates, serving as an effective bridge to HSCT, and it is associated with increased OS and PFS in patients with R/R BCP ALL. The purpose of this study is to explore the efficacy and safety of Inotuzumab Ozogamicin in the treatment of minimal residual disease recurrence after HSCT of ALL patients.

Inclusion Criteria:

1. Patients aged ≥ 15 and ≤ 65 years.
2. Patients diagnosed with CD22+ B-ALL according to 2023 NCCN Acute Lymphoblasts Leukaemias diagnosis standard.
3. CD22+ B-ALL patients with MRD recurrence after HSCT. Ph+ ALL patients were eligible if treatment with 1 or more second-generation BCR::ABL1 tyrosine kinase inhibitors (TKIs) had failed,
4. ECOG performance status score less than 3.
5. Expected survival time #3 months.
6. Patients without serious heart, lung, liver, or kidney disease.
7. Ability to understand and voluntarily provide informed consent.

Exclusion Criteria:

1. Patients who are allergic to the study drug or drugs with similar chemical structures.
2. Pregnant or lactating women, and women of childbearing age who do not want to practice effective methods of contraception.
3. Active infection.
4. Active bleeding.
5. Patients with new thrombosis, embolism, cerebral hemorrhage, or other diseases or a medical history within one year before enrollment.
6. Patients with mental disorders or other conditions whereby informed consent cannot be obtained and where the requirements of the study treatment and procedures cannot be met.
7. Liver function abnormalities (total bilirubin > 1.5 times the upper limit of the normal range, ALT/AST > 2.5 times the upper limit of the normal range or patients with liver involvement whose ALT/AST > 1.5 times the upper limit of the normal range), or renal anomalies (serum creatinine > 1.5 times the upper limit of the normal value).
8. Patients with a history of clinically significant QTc interval prolongation (male > 450 ms; female > 470 ms), ventricular heart tachycardia and atrial fibrillation, II-degree heart block, myocardial infarction attack within one year before enrollment, and congestive heart failure, and patients with coronary heart disease who have clinical symptoms and requiring drug treatment.
9. Surgery on the main organs within the past six weeks.
10. Drug abuse or long-term alcohol abuse that would affect the evaluation results.
11. Patients who have received organ transplants (excepting bone marrow transplantation).
12. Patients not suitable for the study according to the investigator's assessment.