Introduction of imatinib as first-line therapy for chronic myeloid leukemia in Cuba.
INTRODUCTION
Chronic myeloid leukemia is the first malignant disease to be associated with a genetic lesion and is the first leukemia to provide a genotype model conducive to targeted molecular therapy. It is a chronic clonal myeloproliferative disorder, originating in a pluripotent stem cell common to all three hematopoietic lineages, characterized by overproduction of myeloid cells in all stages of maturation. Approval of the use of imatinib in the United States in 2001 and its introduction in the treatment of chronic myeloid leukemia changed the evolution and prognosis of the disease and began the era of molecular therapy for malignancies. Imatinib is highly effective and causes fewer adverse reactions than earlier treatments based on interferon and hydroxyurea. In Cuba, chronic myeloid leukemia has been treated with interferon since 1998. Starting in 2003, imatinib was gradually introduced for use in newly-diagnosed chronic myeloid leukemia patients.


OBJECTIVE
Evaluate the use of imatinib as first-line therapy for chronic myeloid leukemia in a group of Cuban patients, based on hematologic, cytogenetic, and molecular response; overall and event-free survival rates; and most frequency and severity of adverse reactions.


METHODS
During May 2003 to May 2008, 33 newly-diagnosed chronic myeloid leukemia patients (25 adults, 8 children; <6 months from diagnosis) received a single daily oral dose of imatinib 400 mg from the time of study enrollment. Variables used: (1) to evaluate treatment efficacy: hematologic, cytogenetic, and molecular response; overall and event-free survival; and (2) to evaluate safety: presence of adverse reactions leading to definitive interruption of treatment or death.


RESULTS
Complete hematologic response occurred in 100% of patients, major cytogenetic response in 90.9%, and complete cytogenetic response in 48.5%. Molecular response occurred in 36.4% of patients. With a mean follow-up of 39 months, overall survival was 96% and estimated five-year event-free survival was 85%. No adverse reactions occurred in 39.5% of patients. Adverse reactions most frequently observed were myelosuppression (24.2%) and digestive disorders (21.2%). These were followed, in decreasing order, by edema, primarily orbital (9.1%), skin depigmentation (3%), and cardiac arrhythmias (3%).


CONCLUSIONS
In the present study, imatinib was effective first-line therapy for patients with newly-diagnosed chronic myeloid leukemia, as determined by overall and event-free survival rates. No severe adverse reactions were observed.