DNA Methylation of Tumor Suppressor Genes in Clinical Remission Predicts the Relapse Risk in Acute Myeloid Leukemia

Epigenetic changes play an important role in leukemia pathogenesis. DNA methylation is among the most common alterations in leukemia. The potential role of DNA methylation as a biomarker in leukemia is unknown. In addition, the lack of molecular markers precludes minimal residual disease (MRD) estimation for most patients with hematologic malignancies. We analyzed the potential of aberrant DNA promoter methylation as a biomarker for MRD in acute leukemias. Quantitative real-time PCR methods with bisulfite-modified DNA were established to quantify MRD based on estrogen receptor α (ERα) and/or p15 INK4B methylation. Methylation analyses were done in >370 DNA specimens from 180 acute leukemia patients and controls. Methylation of ERα and/or p15 INK4B occurred frequently and specifically in acute leukemia but not in healthy controls or in nonmalignant hematologic diseases. Aberrant DNA methylation was detectable in >20% of leukemia patients during clinical remission. In pediatric acute lymphoblastic leukemia, methylation levels during clinical remission correlated closely with T-cell receptor/immunoglobulin MRD levels ( r = +0.7, P P = 0.003). Many patients with acute leukemia in clinical remission harbor increased levels of aberrant DNA methylation. Analysis of methylation MRD might be used as a novel biomarker for leukemia patients9 relapse risk. [Cancer Res 2007;67(3):1370–7]