The present study describes a patient with high-risk chronic myelomonocytic leukemia (CMML), for whom decitabine therapy achieved partial remission, prior to a sudden transformation to acute myeloid leukemia (AML) and an inferior outcome. The 53-year-old male reported easily bruising for 5 months. Examination indicated a diagnosis of CMML. Chromosome analysis identified a 48, XY, +8, +21 karyotype, classifying the patient as high-risk, according to a clinical/molecular CPSS (CPSS-Mol) model. Gene sequencing detected a mutation in DNA methyltransferase 3α, which is relatively rarely identified in CMML and has recently been reported to have an independent prognostic impact on overall survival time. Partial remission was achieved with decitabine treatment, and hematologic improvement was observed subsequent to 2 cycles of treatment. However, a sudden transformation to AML led to fatality of the patient. This case suggests that decitabine may be an effective therapeutic for high-risk CMML; however, the response may be temporary, and the ultimate outcome may be extremely poor. Therefore, novel treatment strategies of CMML, including combination therapies with decitabine, or targeted drugs, including Janus kinase inhibitors or granulocyte-macrophage colony stimulating factor monoclonal antibodies, require investigation.
Keywords: DNA methyltransferase 3α mutation; acute myeloid leukemia; chronic myelomonocytic leukemia; decitabine; partial remission.