Inotuzumab as Post-Trasplantation Therapy for Adult High-risk B-cell Precursor Acute Lymphoblastic Leukemia

Inclusion Criteria: 1. Patient is, in the investigator's opinion, willing and able to adhere/comply with visit schedule and other protocol requirements. 2. Patient must be able to understand the study procedures. 3. Patients aged ≥18 years at the time of signing the informed consent form. 4. Patient must have an Eastern Cooperative Oncology Group (ECOG) performance status score of ≤ 2. 5. Patient with CD22-positive high risk ALL according to any of the following criteria: i. Definition of high risk ALL according to the PETHEMA LAL 2019 protocol criteria including MRD stratification at the end of induction and during treatment and adverse cytogenetics at diagnosis (hypodiploid karyotype, KMT2A (MLL) alterations, homozygous TP53 deletions/mutations, and IKZF1 and CDKN2A/B deletions). ii. Patients who are in first CR at the time of transplantation, irrespective of MRD status as assessed by immunophenotypic study. iii. Allo-HSCT from an HLA-identical, mismatched or haploidentical sibling or unrelated donor, with myeloablative, reduced toxicity or non-myeloablative conditioning. iv. Stable hematopoietic engraftment defined by neutrophils \>1000/μL for at least 3 consecutive days and platelets \>50000/μL for 7 days with transfusion independence and donor chimerism \>90% assessed in peripheral blood. Exclusion Criteria: 1. Prior exposure to inotuzumab ozogamicin or known hypersensitivity to inotuzumab ozogamicin or to any of its excipients. 2. Ph-positive lymphoblastic leukemia 3. Cord blood HSCT. 4. Creatinine clearance \<30 ml/minute. 5. Bilirubin, GOT and GPT \> 2 times the upper limit of the institution's reference values. 6. History of previous liver disease or hepatic veno-occlusive disease/sinusoid obstruction syndrome. 7. Active hepatitis B or C 8. Fungal infection or relevant uncontrolled infection. 9. Active grade 3-4 acute graft-versus-host disease or acute or chronic hepatic graft-versus- host disease grade ≥2 10. Graft-versus-host disease prophylaxis with sirolimus at enrolment that cannot be discontinued prior to initiation of trial treatment. 11. Absence of haematological recovery 12. Uncontrolled concomitant disease (cardiac, renal, pulmonary, psychiatric). 13. Uncontrolled non-hematological tumor 14. Any serious medical condition or psychiatric illness that would interfere in understanding of the informed consent form. 15. Any serious medical condition that places the subject at an unacceptable risk if he or she participates in this study. 16. Women who are pregnant or breastfeeding, or who intend to become pregnant during participation in the study, or women of childbearing potential who are unwilling or unable to use a highly effective contraceptive method during treatment and for at least 8 months after the last dose; and male participants with female partners of childbearing potential who are unwilling or unable to use a highly effective contraceptive method during treatment and for at least 5 months after the last dose.