title: Global hypomethylation is an independent prognostic factor in diffuse large B cell lymphoma.
abstract: Global hypomethylation has been linked to disease progression in several cancers, but has not been reported for Diffuse Large B Cell Lymphoma (DLBCL). This study aimed to assess global methylation in DLBCL and describe its prognostic value. Mean LINE1 methylation, a validated surrogate measure for global methylation, was measured in DNA from 67 tumor biopsies. Additionally, cell-free circulating DNA (cfDNA) in plasma samples from 74 patients was tested to assess the feasibility of global hypomethylation as a biomarker in liquid biopsies. LINE1 methylation was assessed using a commercially available kit, based on pyrosequencing of PCR amplified bisulfite-treated DNA. Global hypomethylation was detected in a subset of cases and was associated with poor overall survival in both tumor biopsies (P = .001) and cfDNA (P = .009). It was the strongest risk factor in multivariate analysis in both biopsies (HR: 10.65, CI: 2.03-55.81, P = .005) and cfDNA (HR: 11.87, CI: 2.80-50.20, P = .001), outperforming conventional clinical risk factors. Finally, hierarchical cluster analyses were performed for the cfDNA samples using previously published gene-specific methylation data. This analysis shows that global hypomethylation co-occurs with other epigenetic abnormalities, including DAPK1 promoter hypermethylation. In conclusion, we have shown that global hypomethylation is strongly associated with poor survival in DLBCL both when present in tumor biopsy DNA and when detected in plasma cfDNA, and has potential for clinical application as a prognostic biomarker.
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Eileen
authors.identifier: http://orcid.org/0000-0003-3756-6094
authors.initials: E
authors.lastname: Wedge
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Jakob Werner
authors.identifier: http://orcid.org/0000-0002-7315-3775
authors.initials: JW
authors.lastname: Hansen
authors.affiliation: Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen.
authors.forename: Christian
authors.initials: C
authors.lastname: Garde
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Fazila
authors.initials: F
authors.lastname: Asmar
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Dorte
authors.initials: D
authors.lastname: Tholstrup
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Søren Sommer
authors.initials: SS
authors.lastname: Kristensen
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.|Department of Pathology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Helga D
authors.initials: HD
authors.lastname: Munch-Petersen
authors.affiliation: Department of Pathology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ralfkiaer
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Grønbaek
authors.affiliation: Department of Haematology, Rigshospitalet, Copenhagen, Denmark.|Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
authors.forename: Lasse Sommer
authors.initials: LS
authors.lastname: Kristensen
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor; D001706:Biopsy; D016000:Cluster Analysis; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000097:blood / Q000235:genetics; D064550:Death-Associated Protein Kinases / Q000235:genetics; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D020084:Long Interspersed Nucleotide Elements; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011401:Promoter Regions, Genetic; D016016:Proportional Hazards Models; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; C579096:DAPK1 protein, human; D064550:Death-Associated Protein Kinases