Antiproliferative Activity and Mechanism of Action of Fatty Acid Derivatives of Gemcitabine in Leukemia and Solid Tumor Cell Lines and in Human Xenografts

Abstract
Gemcitabine is a deoxycytidine analog, which can be inactivated by deamination catalyzed by deoxycytidine deaminase (dCDA). Altered transport over the cell membrane is a mechanism of resistance to gemcitabine. To facilitate accumulation, the fatty acid derivative CP‐4125 was synthesized. Since, the fatty acid is acylated at the site of action of dCDA, a decreased deamination was expected. CP‐4125 was equally active as gemcitabine in a panel of rodent and human cell lines and in human melanoma xenografts bearing mice. In contrast to gemcitabine, CP‐4125 was not deaminated but inhibited deamination of deoxycytidine and gemcitabine. Pools of the active triphosphate of gemcitabine increased for over 20 hr after CP‐4125 exposure, while these pools decreased directly after removal of gemcitabine. In conclusion: CP‐4125 is an interesting new gemcitabine derivative.