Phosphoramidate ProTides of the Anticancer Agent FUDR Successfully Deliver the Preformed Bioactive Monophosphate in Cells and Confer Advantage over the Parent Nucleoside

Abstract

The fluorinated pyrimidine family of nucleosides continues to represent major current chemotherapeutic agents for treating solid tumors. We herein report their phosphate prodrugs, ProTides, as promising new derivatives, which partially bypass the dependence of the current drugs on active transport and nucleoside kinase-mediated activation. They are also resistant to metabolic deactivation by phosphorolytic enzymes. We report 39 ProTides of the fluorinated pyrimidine FUDR with variation in the aryl, ester, and amino acid regions. Notably, only certain ProTide motifs are successful in delivering the nucleoside monophosphate into intact cells. We also find that the ProTides retain activity in mycoplasma infected cells, unlike FUDR. Data suggest these compounds to be worthy of further progression.

Synthesis of Nucleoside Phosphate and Phosphonate Prodrugs

“…In some cases, they both provide similar yields like in the case of 2′- C -methyl-2-amino-6-substituted-purine ribonucleoside analogs 183 and 5-FdU (Scheme 105). 184 …”

Prodrugs of Phosphonates and Phosphates: Crossing the Membrane Barrier

“…Simple phenyl esters may well be the most extensively employed substructure [130,131], especially in nucleotide analogues such of the general structure 62 [116,127,132–136]. However in cases such as the hydroxamic acid 63, an inhibitor of 6-phosphogluconate dehydrogenase for use in trypanosomiasis, addition of simple substituents such as methyl groups to the phenyl ring has resulted in more than a 10-fold increase in potency [137].…”

Fluorinated Nucleosides as an Important Class of Anticancer and Antiviral Agents

“…Delivery of the free 5'-monophosphate form of a nucleoside analogue inside a cell is particularly important as the first phosphorylation is considered as the rate-limiting step in the activation of most nucleoside analogues. The application of the 5'-phosphoramidate approach to FdUrd (2) led to the discovery and further clinical development of L-alanine-based 5'-ProTide NUC-3373 (55) [35]. Preclinical in vitro data has shown that NUC-3373 exerts its cytostatic activity independently of thymidine kinase in TK-deficient cell lines.…”