Method for predicting sensitivity of a patient suffering from cancer to DNA methylation inhibitor therapy uses in vitro in cancer cells taken from the patient. Cells are compared with parent type cells for expression of bromodomain containing genes, of other listed genes, and/or of bromodomain containing proteins. Mutations involving the amino acid sequence of bromodomain containing genes and/or mutations involving non-synonymous change in amino acid sequence of other genes may be examined. The half maximal inhibitory concentration (IC50) of inhibitors of DNA methyltransferase, histone acetyltransferase, histone methyltransferase, histone deacetylases, and/or histone demethylases are determined. Increase in (IC50) signifies cross-resistance. The half maximal inhibitory concentration (IC50) of a selective BET bromodomain inhibitor is also determined, wherein decrease in the (IC50) signifies sensitivity. A combination therapy for cancers using bromodomain inhibitors in combination with DNA methylation inhibitors is also provided.
