Combination chemotherapy of cancer using the inhibitor of DNA methylation 5-aza-2'-deoxycytidine (decitabine)

Abstract

The epigenetic alterations marked by DNA methylation contribute to the malignant transformation of cells by silencing critical genes responsible for the regulation of growth. The potent DNA methylation inhibitor 5-aza-2'-deoxycytidine (decitabine; DAC) has shown effectiveness in patients with myeloid malignancies. However, the responses are of short duration. The effectiveness of the DAC therapy may be limited by its incapacity to reactivate enough tumor suppressor genes. Other epigenetic mechanisms, such as the histone modification of target genes, may also hinder gene reactivation by DAC. The dose limiting toxicity of DAC is myelosuppression, which limits the duration of this therapy for clinical use. The clinical effectiveness of DAC may be enhanced by its use in combination with other agents that have diverse mechanisms of action. In this literature review, we summarize the results of preclinical and recent clinical trials of DAC used in combination with other agents to treat cancer. This review was conducted by searching online databases to analyze the available evidence regarding this area of interest. We looked at the combination of DAC with other epigenetic agents, cytotoxic agents, tyrosine kinase inhibitors, biochemical modulators and non-toxic agents. The data compiled suggests that combination epigenetic therapy is feasible, moderately toxic and has promising clinical potential. Preclinical studies showed that some combinations of DAC have additive to synergistic antineoplastic action as compared to DAC alone. The data indicate that combination chemotherapy with DAC merits further investigation. This review may be helpful for the future design of clinical trials using DAC in combination for cancer therapy.