Michiyo Asano 1 , Junko H Ohyashiki 2 , Chiaki Kobayashi-Kawana 1 , Tomohiro Umezu 1 , 3 , Satoshi Imanishi 3 , Kenko Azuma 3 , Daigo Akahane 1 , Hiroaki Fujimoto 1 , Yoshikazu Ito 1 , Kazuma Ohyashiki 1
30 May 2019
Purpose: Monitoring response and resistance to 5-azacitidine (AZA) is essential when treating patients with myelodysplastic syndrome (MDS). To quantify methylated DNA not only in the promoter region but also in the gene body, we established a single-molecule methylation assay (SMMA).
Patients and methods: We first investigated the methylation extent (expressed as methylation index [MI]) by SMMA among 28 MDS and 6 post-MDS acute myeloid leukemia patients. We then analyzed the MI in 13 AZA-treated patients.
Results: Whole-blood DNA from all 34 patients had low MI values compared with healthy volunteers ( P<0.0001). DNA hypomethylation in MDS patients was more evident in neutrophils ( P=0.0008) than in peripheral mononuclear cells ( P=0.0713). No consistent pattern of genome-wide DNA hypomethylation was found among MDS subtypes or revised International Prognostic Scoring System (IPSS-R) categories; however, we found that the MI was significantly increased for patients at very high risk who were separated by the new cytogenetic scoring system for IPSS-R ( P=0.0398). There was no significant difference in MI before AZA, regardless of the response to AZA ( P=0.8689); however, sequential measurement of MI in peripheral blood demonstrated that AZA non-responders did not have normalized MI at the time of next course of AZA ( P=0.0352).
Conclusion: Our results suggest that sequential SMMA of peripheral blood after AZA may represent a non-invasive monitoring marker for AZA efficacy in MDS patients.