Philadelphia chromosome (Ph) is a reciprocal chromosomal translocation t(9;22）(q34;q11), which leads to the formation of the BCR/ABL oncogene. Ph is the most frequent cytogenetic abnormality in ALL characterized by poor outcome. With the BCR/ABL protein TKI, imatinib, in the combination chemotherapy regimes for newly diagnosed Ph+ ALL, more than 95% of patients can achieve complete remission(CR). Several studies have shown decreased relapse rates and improved disease-free survival for patients with imatinib-based treatment prior to allo-HSCT. However, the efficacy of maintenance therapy with imatinib after transplant for Ph+ ALL patients is still uncertain. In addition, acquired resistance to imatinib is frequently caused by point mutations in BCR/ABL that inactivate imatinib.