BACKGROUND/AIM: Imatinib mesylate, a tyrosine kinase inhibitor with specific 
activity against the breakpoint cluster region--Abelson murine leukemia 
(BCR-ABL) tyrosine kinase has been developed for treatment of chronic 
myelogenous leukemia (CML). Its hematologic and cytogenetic effects have been 
evaluated in a series of clinical trials. The aim of this study was to report 
hematologic and cytogenetic response in CML patients during the treatment with 
imatinib mesylate.
METHODS: A total of 21 patients were treated and observed from July 2006 to 
December 2008. The median time from CML diagnosis was no more than 12 months, so 
all the patients received previous treatment with hydroxyurea for which the 
median time was 3 months. The patients received imatinib mesylate in an 
effective oral dose of 400 to 800 mg daily, which was followed with peripheral 
blood counts, bone marrow examination, and cytogenetic studies at 6, 12, 18 and 
24 months.
RESULTS: Complete hematologic responses were reported for 19 (90.48%) of 21 
patients studied. Among 19 patients who had a response, 16 (86%) did so within 3 
months. The best cytogenetic response rate at any time during the study 
treatment with imatinib mesylate, among 14 patients in which cytogenetic 
response evaluated was: complete cytogenetic response in 7 (50%) patients, 
partial cytogenetic response in 6 (42.9%) patients and minor cytogenetic 
response in 1 (7.1%) patient. No patients had progressed to accelerated or 
blastic phase. The most frequent adverse effects that seemed to be related to 
treatment with imatinib mesylate were edema and musculoskeletal pain; overall, 
most were mild. Only one patient discontinued treatment because of hematologic 
toxic effects.
CONCLUSION: The results obtained in this study confirm that imatinib mesylate 
induces a complete hematological and cytogenetic response in a high percentage 
of patients with chronic-phase CML.