Discovery of 5′-Substituted 5-Fluoro-2′-deoxyuridine Monophosphate Analogs: A Novel Class of Thymidylate Synthase Inhibitors

5-Fluorouracil and 5-fluorouracil-based prodrugs have been used clinically for decades to treat cancer. Their anticancer effects are most prominently ascribed to inhibition of thymidylate synthase (TS) by metabolite 5-fluoro-2 '- deoxyuridine 5 '-monophosphate (FdUMP). However, 5-fluorouracil and FdUMP are subject to numerous unfavorable metabolic events that can drive undesired systemic toxicity. Our previous research on antiviral nucleotides suggested that substitution at the nucleoside 5 '-carbon imposes conformational restrictions on the corresponding nucleoside monophosphates, rendering them poor substrates for productive intracellular conversion to viral polymerase-inhibiting triphosphate metabolites. Accordingly, we hypothesized that 5 '-substituted analogs of FdUMP, which is uniquely active at the monophosphate stage, would inhibit TS while preventing undesirable metabolism. Free energy perturbation-derived relative binding energy calculations suggested that 5 '(R)-CH3 and 5 '(S)-CF3 FdUMP analogs would maintain TS potency. Herein, we report our computational design strategy, synthesis of 5 '-substituted FdUMP analogs, and pharmacological assessment of TS inhibitory activity.

Automated summary

5-Fluorouracil and its derivatives have been used for cancer treatment for many years. However, they can cause unwanted systemic toxicity due to unfavorable metabolic events. In this study, we designed and synthesized 5'-substituted analogs of FdUMP to inhibit thymidylate synthase while preventing undesirable metabolism. Computational calculations and pharmacological assessments demonstrated that these analogs maintain the potency of thymidylate synthase inhibition.