Effect of Prophylactic Tyrosine Kinase Inhibitor Therapy Post-transplants on Philadelphia Chromosome-positive Acute Lymphoblastic Leukemia Undergoing Allo-HSCT With Minimal Residual Disease 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.