A phase I biological study of MG98, an oligodeoxynucleotide antisense to DNA methyltransferase 1, in patients with high-risk myelodysplasia and acute myeloid leukemia

Clin Cancer Res. 2008 Apr 15;14(8):2444-9. doi: 10.1158/1078-0432.CCR-07-1320.


Purpose: Epigenetic silencing via aberrant promoter DNA hypermethylation of normal genes has been described as a leukemogenic mechanism in myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML). We hypothesized that MG98, an oligonucleotide antisense to DNA methyltransferase 1 (DNMT1), could reverse malignant phenotypes by down-regulating DNMT1 and inducing reexpression of hypermethylated genes. This phase I study was conducted to determine a biologically effective dose and describe the safety of MG98 in MDS/AML.

Experimental design: Twenty-three patients with MDS (n = 11) and AML (n = 12) were enrolled. Biologically effective dose was defined as the dose at which > or =50% of patients experienced >50% reduction in DNMT1 expression with acceptable toxicity. Escalating doses of MG98 were administered according to two schedules (2-hour i.v. bolus followed by 5-day continuous i.v. infusion every 14 days, or 14-day continuous i.v. infusion every 21 days).

Results: DNMT1 down-regulation was observed in 8 patients. However, biologically effective dose was not reached. Reexpression of target genes (P15, WIT1, and ER) was observed in 12 patients but did not correlate with DNMT1 down-regulation. Escalation was stopped due to dose-limiting toxicities (bone pain, nausea, and fever). No objective clinical response was observed. Disease stabilization occurred in 6 (26%) patients.

Conclusions: No pharmacodynamic or clinical activity was observed at MG98 doses and schedules administered. Despite this, pursuing DNMT1 down-regulation remains a sound approach for targeting aberrant epigenetics in AML/MDS. Future studies with different formulation and/or doses and schedules will be required to ensure efficient MG98 intracellular uptake and fully evaluate its therapeutic potential.

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases / antagonists & inhibitors*
  • DNA (Cytosine-5-)-Methyltransferases / genetics
  • Female
  • Humans
  • Leukemia, Myeloid, Acute / drug therapy*
  • Male
  • Middle Aged
  • Myelodysplastic Syndromes / drug therapy*
  • Oligodeoxyribonucleotides / adverse effects
  • Oligodeoxyribonucleotides / pharmacokinetics
  • Oligodeoxyribonucleotides / therapeutic use*
  • RNA, Messenger / analysis
  • Thionucleotides / adverse effects
  • Thionucleotides / pharmacokinetics
  • Thionucleotides / therapeutic use*


  • MG 98 phosphorothioate antisense oligodeoxynucleotide
  • Oligodeoxyribonucleotides
  • RNA, Messenger
  • Thionucleotides
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases
  • DNMT1 protein, human