Pharmacology of 5-Aza-2'-deoxycytidine (decitabine)

Semin Hematol. 2005 Jul;42(3 Suppl 2):S9-16. doi: 10.1053/j.seminhematol.2005.05.002.


The preclinical pharmacology of 5-aza-2'-deoxycytidine (decitabine, 5AZA-CdR) is reviewed. 5AZA-CdR, an analogue of deoxycytidine, is a prodrug that requires metabolic activation by deoxycytidine kinase. The active inhibitor in the cell is its triphosphate form (5AZA-dCTP), which incorporates very readily into DNA to produce an inhibition of DNA methyltransferase. The mechanism responsible for the antileukemic action of 5AZA-CdR is related to its reversal of epigenetic silencing by aberrant DNA methylation of genes that suppress leukemiogenesis. 5AZA-CdR is an S-phase-specific agent. At concentrations in the range of micromolars this analogue can induce terminal differentiation and loss of clonogenicity of human leukemic cells. Drug resistance to 5AZA-CdR occurs primarily by reduction in deoxycytidine kinase activity or increase in the activity of cytidine deaminase, the enzyme that inactivates this analogue. 5AZA-CdR is a very potent antileukemic agent in animal models, more effective than the related antileukemic drug, cytosine arabinoside. In humans, 5AZA-CdR has a short half-life of 15 to 25 minutes due to rapid inactivation by liver cytidine deaminase. The major toxicity produced by 5AZA-CdR is myelosuppression. Preliminary clinical studies in patients with hematologic malignancies indicate that 5AZA-CdR is an active chemotherapeutic agent. The optimal dose-schedule for this interesting epigenetic agent with a novel mechanism of action remains to be determined. Translation of the pharmacology of 5AZA-CdR into therapeutic regimens based on scientific rationale can be used to obtain this objective.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Azacitidine / analogs & derivatives*
  • Azacitidine / pharmacokinetics
  • Azacitidine / pharmacology
  • Azacitidine / toxicity
  • Biotransformation
  • Decitabine
  • Humans
  • Leukemia / drug therapy
  • Treatment Outcome


  • Decitabine
  • Azacitidine