Objectives: To evaluate the relationship between cytopenia and cytogenetic response in Imatinib mesylate treated Ph-positive chronic myeloid leukemia (CML) in chronic phase patients.
Methods: Fifty-four patients with Ph + CML in chronic phase received oral administration of Imatinib 400 or 600 mg once a day for 18 months.
Results: In the early phase of Imatinib treatment, rates of severe leukopenia (leukocyte < 2.0 x 10(9) L-1), anemia (hemoglobin < 100 g.L-1) and severe thrombocytopenia (platelet < 50 x 10(9) L-1) were 14.8%, 37.0% and 27.8%, respectively. Hemocytes recovered in most patients with continued therapy. Treatment was interrupted or dosage reduced in a few patients. The lower the hemoglobin and higher the platelet before the regime, the lower the nadir of leukocytes and hemoglobin counts during the treatment. The lower the platelet count before the regime, the lower the nadir of platelets during the treatment. Risk factors for severe leukopenia were thrombocytosis (> or = 500 x 10(9) L-1) and basophilia > or = 5% before the treatment. Risk factors for severe thrombocytopenia were thrombocytopenia (< 100 x 10(9) L-1) and basophilia > or = 5% before the treatment. During the 12-month treatment with Imatinib, the statistically significant lower probabilities of cytogenetic response were observed at all checked points in patients with severe leukopenia, at the end of 3 and 6 months in patients with anemia, at the end of 3 months in patients with severe thrombocytopenia.
Conclusion: Cytopenia is a common side effect in patients with CML in chronic phase treated with Imatinib mesylate. Severe leukopenia is associated with a sustained lower major cytogenetic response, whereas anemia and severe thrombocytopenia influence more for the first 6 months.