Allogeneic Stem Cell Transplantation versus Tyrosine Kinase Inhibitors Combined with Chemotherapy in Patients with Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia

Here we compare outcomes between the tyrosine kinase inhibitors (TKIs) plus chemotherapy regimen and allogeneic hematopoietic stem cell transplantation (transplantation cohort) in patients with Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL) and explore factors associated with prognosis. Data from 145 Ph+ ALL patients were analyzed retrospectively. Patients were treated with imatinib plus chemotherapy and then transplantation or continuous TKIs with chemotherapy based on patient preference. A total of 145 Ph+ ALL patients were recruited for this study (median age, 37 years; range, 14 to 65). Among these patients, 81 were men (55.9%) and 86 underwent IKZF1 detection, which identified 59 patients (68.6%) with IKZF1 deletions. After treatment 136 patients (95.8%) achieved complete remission (CR) eventually. With a median follow-up of 33 months (range, 4 to 114) for CR patients, 77 patients (57.9%) underwent transplantation and 56 (42.1%) received continuous TKIs with chemotherapy. At the 4-year follow-up the cumulative incidence of relapse (CIR), disease-free survival (DFS), and overall survival (OS) were 29.4% (95% confidence interval [CI], 24.9% to 34.4%), 60.9% (95% CI, 56.5% to 65.3%), and 69.2% (95% CI, 65.1% to 73.3%), respectively. Multivariate analysis showed that WBC counts < 30 × 109/L at diagnosis (hazard ratio [HR], 4.2; 95% CI, 1.9 to 9.2; P < .001; HR, 2.6; 95% CI, 1.4 to 4.9; P = .003; HR, 2.7; 95% CI, 1.4 to 5.4; P = .003), 3-log reduction of BCR-ABL levels from baseline after 2 consolidation cycles (HR, 4.4; 95% CI, 1.9 to 9.9; P < .001; HR, 3.1; 95% CI, 1.7 to 5.9; P < .001; HR, 3.5; 95% CI, 1.9 to 8.7; P = .001; defined as "minimal residual disease low level"), and transplantation (HR, 5.0; 95% CI, 2.2 to 11.2; P < .001; HR, 3.3; 95% CI, 1.7 to 6.4; P < .001; HR, 4.1; 95% CI, 1.9 to 8.7; P < .001) were the favorable factors of CIR, DFS, and OS. According to the first 2 risk factors, CR patients were divided into 3 groups: low risk (no factor, n = 42, 31.6%), intermediate risk (1 factor, n = 73, 54.9%), and high risk (2 factors, n = 18, 13.5%). In the low-risk group at the 4-year follow up no significant difference existed between the transplant and nontransplant arms for the probabilities of CIR (8.5% versus 7.7%, P = .671), DFS (88.2% versus 83.9%, P = .426), and OS (96.6% versus 83.3%, P = .128). In the intermediate- and high-risk groups at the 4-year follow-up, CIR (23.6% versus 36.9%, P = .017; 37.5% versus 100.0%, P < .001), DFS (62.4% versus 43.8%, P = .048; 56.2% versus 0%, P < .001), and OS (76.1% versus 47.7%, P = .037; 51.4% versus 6.3%, P = .001) rates were significantly better in the transplant arm than in the nontransplant arm. In surviving patients of the low-risk group, no difference in complete molecular response (CMR) rates (85.7% versus 72.7%, P = .379) between the transplant and nontransplant arms was found. However, in the intermediate-risk group the proportion of CMR was significantly higher in the transplant arm than in the nontransplant arm (82.8% versus 42.9%, P = .006). In the high-risk group 4 of 7 transplant patients (57.1%) were in CMR, and no patients survived in the nontransplant arm. Allogeneic hematopoietic stem cell transplantation confers significant survival advantages for Ph+ ALL patients compared with TKIs plus chemotherapy, especially in intermediate- and high-risk patients.