Diagnosis and treatment of chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a clonal disorder of hematopoietic cells and is a complex of heterogeneous conditions with both myeloproliferative and myelodysplastic features. The diagnosis of CMML is made using morphologic criteria including monocyte-dominant leukocytosis, dysplastic changes, and increased blasts in the bone marrow. Recently, the identification of monocyte subtypes in peripheral blood using multiparameter flow cytometry has been actively studied. Chromosomal abnormalities are the basis of CMML risk stratification, and mutations in several genes including ASXL1 are known to be important not only for the diagnosis and treatment of this disease but also for predicting its prognosis. The standard treatment principles for CMML have not yet been clearly defined; however, hypomethylating agents are mainly considered the frontline therapy in most cases. Although allogeneic hematopoietic stem cell transplantation has limited applications owing to its toxicity, it still plays an important role as the only curative treatment option. Researchers are continuing to develop new drugs for CMML treatment and to prove their clinical usefulness. This review summarizes what is known to date on the diagnosis, treatment, and prognostic factors of CMML and presents future directions by analyzing recent research trends.