Azacytidine is an established nucleoside drug that is well known for its ability to modulate epigenetic gene regulation by inhibition of DNA methylation. Despite recent advances in the clinical development of azacytidine, the use of the drug is limited by its low bioavailability and dependency on variably expressed nucleoside transporters for cellular uptake. We show here that CP-4200, an elaidic acid derivative of azacytidine, has strong epigenetic modulatory potency in human cancer cell lines, as evidenced by efficient depletion of DNA methyltransferase protein, genome-wide DNA demethylation, and robust reactivation of epigenetically silenced tumor suppressor genes. Importantly, however, the cellular uptake of CP-4200 was substantially less dependent on the nucleoside transporters that are known to be involved in azacytidine uptake. In agreement with this notion, CP-4200 showed a significantly higher antitumoral activity than azacytidine in an orthotopic mouse tumor model for acute lymphocytic leukemia. Together, these data represent a detailed characterization of the CP-4200 mode of action and suggest that elaidic acid modification improves the therapeutic efficacy of azacytidine.