Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in early first complete remission improves the long-term outcomes for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Relapse remains a major cause of treatment failure even after allo-HSCT. The prevention of relapse is essential for improving the outcome of Ph+ ALL. Our previous clinical trial (ID: NCT01883219) demonstrated that pre-emptive tyrosine kinase inhibitor (TKIs) administration based on minimal residual disease (MRD) and BCR-ABL mutation after allo-HSCT might reduce the incidence of relapses and improve survival for patients with Ph+ ALL. Moreover, our result suggested that Ph+ ALL with MRD positive pre-transplants had the higher rate of molecular biology relapse. In this study, we will evaluate the safety and efficacy of prophylactic TKI therapy post-transplants on Ph+ ALL undergoing allo-HSCT with MRD positive pre-transplants.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in early first complete remission improves the long-term outcomes for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Relapse remains a major cause of treatment failure even after allo-HSCT. Overall, patients experiencing relapse have a dismal prognosis despite salvage treatment with TKIs. The prevention of relapse is essential for improving the outcome of Ph+ ALL. Strategies to prevent relapse include tyrosine kinase inhibitor (TKIs) use, donor lymphocyte infusions (DLI), CAR-T and so on. At present, the utility of TKIs administration post-transplants is controversial. Our previous clinical trial (ID: NCT01883219) demonstrated that pre-emptive TKI administration based on minimal residual disease (MRD) and BCR-ABL mutation after allo-HSCT might reduce the incidence of relapses and improve survival for patients with Ph+ ALL. Moreover, we found that 58% Ph+ ALL with MRD positive pre-transplants would MRD positive post-transplants, whereas only 11.4% Ph+ ALL with MRD negative pre-transplants would MRD positive post-transplants, suggesting that Ph+ ALL with MRD positive pre-transplants had the higher rate of molecular biology relapse. In this study, we will evaluate the safety and efficacy of prophylactic TKI therapy post-transplants on Ph+ ALL undergoing allo-HSCT with MRD positive pre-transplants.

Inclusion Criteria:

• Patient age of 14-65 years
• Ph+ ALL undergoing allo-HSCT with MRD positive pre-transplants
• Survival > 30 days post-transplants
• MRD negative on day +30 post-transplants

Exclusion Criteria:

• Ph+ ALL undergoing allo-HSCT with MRD negative pre-transplants
• Survival <30 days post-transplants
• MRD positive on day +30 post-transplants
• Any abnormality in a vital sign (e.g., heart rate, respiratory rate, or blood pressure)
• Patients with any conditions not suitable for the trial (investigators' decision)