Prognostic factors for progression in patients with Philadelphia chromosome‐positive acute lymphoblastic leukemia in complete molecular response within 3 months of therapy with tyrosine kinase inhibitors

BACKGROUND: The achievement of a 3-month complete molecular response (CMR) is a major prognostic factor for survival in patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). However, 25% of patients relapse during therapy with tyrosine kinase inhibitors (TKIs). METHODS: The authors reviewed 204 patients with Ph-positive ALL who were treated between January 2001 and December 2018 using the combination of hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) plus a TKI (imatinib, 44 patients 22%; dasatinib, 88 patients 43%; or ponatinib, 72 patients 35%). Progression-free survival (PFS) was defined as the time from the start date of therapy to the date of relapse, death, or last follow-up. Overall survival (OS) was defined as the time from the start date of therapy to the date of death or last follow-up. RESULTS: Overall, a 3-month CMR was observed in 57% of patients, including 32% of those who received imatinib, 52% of those who received dasatinib, and 74% of those who received ponatinib. The median follow-up was 74 months (imatinib, 180 months; dasatinib, 106 months; ponatinib, 43 months). Among 84 patients in 3-month CMR, 17 (20%) proceeded to undergo allogeneic stem cell transplantation (ASCT). The 5-year PFS and OS rates were 68% and 72%, respectively. By multivariate analysis, ponatinib therapy was the only significant favorable independent factor predicting for progression (P = .028; hazard ratio, 0.388; 95% CI, 0.166-0.904) and death (P = .042; hazard ratio, 0.379; 95% CI, 0.149-0.966). ASCT was not a prognostic factor for PFS and OS by univariate analysis. CONCLUSIONS: In patients with Ph-positive ALL, ponatinib is superior to other types of TKIs in inducing and maintaining a CMR, thus preventing disease progression. ASCT does not improve outcome once a 3-month CMR is achieved.