Prognostic factors associated with complete cytogenetic response in patients with chronic myelogenous leukemia on imatinib mesylate therapy

Imatinib mesylate, a selective Bcr-Abl tyrosine kinase inhibitor, has proved to be most effective therapy of Philadelphia chromosome-positive chronic myelogenous leukemia. Imatinib induces complete haematological and cytogenetic response in high percentage of patients.

The aim of this study was to identify potential prognostic factors before beginning treatment with imatinib associated with complete cytogenetic response.

We analyzed 20 patients with newly diagnosed Philadelphia positive chronic myelogenous leukemia treated at our institution from June 2006 until May 2009. These patients were treated with imatinib mesylate in oral dose of 400 to 800 mg daily. Complete blood counts were performed every month, while serum chemistry evaluations and bone marrow evaluations including morphology and cytogenetics were performed every 6 months.

Of the 20 patients analyzed in this study, 19 (95%) achieved complete haematologic response within three months. In all patients cytogenetic analyses were done and all have achieved absolute cytogenetic response. The best cytogenetic response rate at any time during study treatment among 20 patients was: complete cytogenetic response in 15, partial cytogenetic response in three and minor cytogenetic response in two patients. Among 11 observed base-line patients' characteristics five were independent predictors of a high rate of complete cytogenetic response; the absence of blasts and basophils in peripheral blood, the presence of less than 5 percent of bone marrow blasts, white blood cell count less than 10 x 10(9)/L and the absence of splenomegaly (p < 0.01).

Our results showed that some pre-treatment characteristics of patients might be the cause of differences in treatment outcome. On the basis of this analysis, we identified several pre-treatment patients' characteristics to be independent prognostic factors for achievement of complete cytogenetic response.