OBJECTIVETo investigate the role of imatinib in induction therapy for newly diagnosed adult patients with Philadephia chromosome-positive acute lymphoblastic leukemia (Ph⁺ALL), as well as the status of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the treatment of adult Ph⁺ ALL in imatinib era.

METHODSRetrospectively analyzed 97 newly diagnosed adult Ph⁺ ALL patients from 2005 to 2013. According to whether administrated imatinib in the induction therapy and the administrating duration (≥3 d) , they were divided into imatinib (n=37) and non-imatinib group (n=60), and the former group was further divided into early-use (n=26) and late-use imatinib groups (n=11) (bounded by the fourteenth day of induction chemotherapy). We compared the overall response rate (ORR) and the negative rate of BCR-ABL fusion gene in patients who achieved complete remission (CR) or CR with incomplete recovery of blood cells (CRi) among the three groups at the end of the first induction therapy. There were 44 cases underwent allo-HSCT (transplant group) and 33 cases only adopted imatinib-based chemotherapy (non-transplant group) in 77 patients who administrated imatinib as a maintenance therapy, we further compared the incidences of overall survival (OS) , disease-free survival (DFS), relapse and nonrelapse mortality (NRM) between the two groups; and dynamically monitor polymerase chain reaction (PCR) negativity of patients who were in CR1 state before transplant (n=34) at the following timepoints of achieving CR or CRi, the first consolidation therapy, beginning the pretreatment of transplant and attaining hematopoietic reconstruction after transplant.

RESULTSAfter the first induction therapy, the ORR of imatinib group was significantly higher than of non-imatinib group (97.3%, 72.9% respectively, P=0.002), but early-use and late-use imatinib groups had no statistical significance in ORR (100% , 90.9% respectively, P=0.297); the rate of negativity of imatinib and non- imatinib groups were 20.0% and 0 respectively (P=0.041) in patients who achieved CR or CRi. The negative rate of patients in CR1 state before transplant attained 20.8%, 42.3%, 51.8%, 76.8%, respectively at the previously described 4 timepoints. And the differences between the fourth and the third, the third and the first timepiont all reached statistical significance (P=0.044, 0.022, respectively). The 5-year OS of transplant and non- transplant groups showed statistical difference (47.0%, 28.0% respectively, P=0.016), also for 5-year DFS (P=0.001) and the cumulative rate of relapse (P=0.000) of the former surpassing the latter; the cumulative rate of NRM between these two groups had no statistical significance (P=0.370).

CONCLUSIONConventional induction chemotherapy in combination with imatinib in the first induction therapy of adult Ph⁺ ALL, not only improved the rate of hematologic remission, also the rate of molecular response. Imatinib used as a consolidation and maintenance therapy after remission, and allo-HSCT scheduled as soon as possible improved the prognosis.