Clinical effects of the CD13/CD33 ratio on the prognosis of myelodysplastic syndrome treated with azacitidine

Myelodysplastic syndromes (MDS) are a group of clonal hematological disorders that are characterized by ineffective hematopoiesis, leading to blood cytopenias and a high risk of progression to acute myeloid leukemia (AML). The hypomethylating agent, azacitidine (AZA) is a cytidine analog that inhibits a group of enzymes called DNA methyltransferases and leads to the demethylation of cytosine residues in promoter-associated CpG islands. The hypomethylation and subsequent reversal of the transcriptional inhibition of important tumor suppressor and DNA repair genes are considered to be the main mechanisms of action of AZA. AZA is an effective therapy not only for low-risk MDS, but also for high-risk MDS and oligoblastic AML [1]. Although prognostic scoring indexes, such as IPSS, IPSS-R, and WPSS, have already been reported [2–4], prognostic factors for response and survival in MDS patients treated with AZA remain unknown. Flow cytometry is widely used in the diagnosis and monitoring of MDS [5]. An aberrant phenotype of blasts and the asynchronous expression of maturation antigens in the myelomonocytic series were previously reported to be associated with overall survival (OS) [6]. These abnormalities are regarded as the biologic signals of abnormal maturation and their increase may be a sign of clone progression [6]. We herein investigated the relationship between immunophenotyping and the prognosis of MDS patients treated with AZA. We conducted a retrospective review of MDS patient data between January 2007 and December 2018 at the Japanese Red Cross Society Wakayama Medical Center. The present study comprised patients diagnosed with MDS who received AZA. AZA was intravenously or subcutaneously administered at a dose of 75mg/m on days 1–7 every 28days. Disease diagnoses were made according to the WHO 2008 classification [7]. Cytogenetic analyses were performed using standard G-banding with trypsin-Giemsa staining. Karyotypes were interpreted using the International System for Cytogenetic Nomenclature criteria [8]. IPSS, IPSSR, and WPSS were used in risk assessments [2–4]. Responses were evaluated according to the IWG 2006 criteria [9]. The present study was conducted in accordance with the principles of the Declaration of Helsinki. Threecolor flow cytometry was performed to evaluate the phenotypes of blast cells before the beginning of AZA therapy. Mononuclear cells were stained with the following mononuclear antibodies: a fluorescein isothiocyanate (FITC)-conjugated monoclonal antibody, CD3, CD5, CD8, CD15, CD19, CD25, CD34, HLA-DR (Becton Dickinson), phycoerythrin (PE)-conjugated antibodies, CD4, CD11b, CD13, CD14, CD33, CD45 (Becton Dickinson), a peridinin chlorophyll protein (PerCP)-conjugated antibody, CD10, CD117, and glycophorin A (Immunotech). A gate was set for identifying blast cells characterized by intermediate CD45 expression and low side scatter properties. At least 10,000 events were acquired for most samples. The expression of each antigen was considered to be positive when at least 20% of gated cells were fluorescent relative to negative controls. The phenotypes of blast cells were analyzed using a flow cytometer (FACSCalibur; Becton). Fisher’s exact test and the Mann–Whitney U test were used to assess the significance of differences. OS was calculated as the time from the date of diagnosis to death from any cause and was assessed using the Kaplan–Meier method and Log-rank test. Factors affecting clinical outcomes were analyzed using univariate and multivariate Cox’s proportional hazard regression models. A p-value less than . 05 was considered to be significant. Statistical analyses were performed with the SPSS 11.5 system. The median follow-up of the entire population was 32months (range 2–132months). A total of 119 patients with MDS were examined and included 73 males (61%) and 46 females (39%) with a median age of 69 years (range 20–86 years). A total of 112 patients (94%) did not receive any treatments; three (2%) received lenalidomide before AZA, 2 (2%) vitaminic support, and 2 (2%) erythroid-stimulating agents. According to the WHO classification, 12 patients (10%) were diagnosed with RCUD or RARS, 9 (8%) with RCMD, 41 (34%) with RAEB-1, 42 (35%) with RAEB-2, and 3 (2%) with MDS with del 5q.