Decitabine Activity in Chronic Myelomonocytic Leukemia Patients

Background: Epigenetic therapy with hypomethylating agents has recently been approved for the treatment of myelodysplastic syndromes (MDS) in Argentina. Chronic Myelomonocytic Leukemia (CMML) is a hybrid disorder characterized by myeloid proliferation and erythroid-megakaryocytic dysplasia. Subgroup analyses (

Study objective: To compare the clinical and hematological improvement with decitabine among patients with CMML to those with other MDS subtypes.

Methods: We enrolled patients with MDS who received decitabine between July 2007 and June 2008 at 17 centers in our country. Inclusion criteria were ≥18 years of age, de novo or secondary MDS and an International Prognosis Scoring System (IPSS) score ≥0.5. Exclusion criteria were diagnosis of acute myeloid leukemia (AML) or other progressive malignant disease. Patients with prior therapy for MDS/CMML were not excluded. Patients were categorized as having CMML or another sub-type of MDS according to FAB/WHO criteria. All pts received decitabine 20 mg/m² IV over 1 hour once daily for 5 consecutive days repeating every 4 weeks. Overall improvement rate (complete response + marrow complete response + partial response + hematologic improvement) was compared between cohorts with chi-square and Fisher’s tests.

Results: There were 11 patients with CMML and 27 patients with other subtypes of MDS. Demographic characteristics are summarized in the table. All CMML patients were BCR/ABL negative. Three patients had CMML type II (WHO classification, Blasts ≥10% in marrow and/or ≥5% in peripheral blood) and 8 had CMML type I. Four patients with CMML had proliferative features with WBC >13000/mm³ and splenomegaly at the time of diagnosis. The overall response was 73% in patients with CMML and 33% in patients with other MDS sub-types (p=0.003). Median time to first response in CMML pts was 2 cycles. Tolerability was acceptable in both groups with no significant differences.

Conclusion: Although our study group is small, decitabine demonstrated marked activity in CMML. Additional study of decitabine therapy in CMML is warranted.