Dasatinib, even at low doses, is an effective second-line therapy for chronic myeloid leukemia patients resistant or intolerant to imatinib. Results from a real life-based Italian multicenter retrospective study on 114 patients.

Purpose Dasatinib is remarkably effective in treating patients with chronic myeloid leukemia (CML) resistant or intolerant to front-line imatinib. To date, most of the available data come from multicenter study in which the patients were censored for diverse reasons. Thus, further studies based on non selected populations are indeed opportune. Patients and Methods A total of 124 unselected patients with CML resistant or intolerant to imatinib received Dasatinib as second line therapy outside from clinical trials. Response (hematologic, cytogenetic and molecular), toxicities according to NCI-CTC, discontinuation/dose reduction of Dasatinib, event-free survival (EFS) and overall survival (OS) were evaluated. Results At 12 months, cumulative incidences of complete hematologic response (CHR), complete cytogenetic response (CCyR) and major molecular response (MMR) were 94%, 51% and 32% respectively. Cumulative EFS and OS were 91 and 93% respectively. These data are in line with those of clinical trials, but the population of the present study was not selected. Intriguingly, neither the dose nor the duration nor the response to prior imatinib affected the probability of achieving CCyR at 1 year with dasatinib (p= 0.7, 0.9 and 0.8 respectively). Moreover, we observed a statistically significant better outcome in term of both DFS and OS for patients not discontinuing dasatinib, even at low doses (p=0.05 and p=0.04), with respect to those who discontinued the drug due to grade III-IV toxicity. Conclusions Dasatinib as second line therapy is safe and highly effective for unselected patients with CML either resistant or refractory to IM even outside from clinical trials. Neither the dose nor the duration nor the response to imatinib affects the probability to respond to dasatinib. These findings indicate an increase possibility of cure for unselected patients resistant or intolerant to imatinib submitted to second line therapy with dasatinib in everyday clinical practice.