Human carboxylesterase-2 hydrolyzes the prodrug of gemcitabine (LY2334737) and confers prodrug sensitivity to cancer cells.

Purpose: The oral prodrug of gemcitabine LY2334737 is cleaved systemically to gemcitabine; the mechanism responsible for hydrolysis is unknown. LY2334737 cytotoxicity was tested in the NCI-60 panel; mining of microarray expression data identified carboxylesterase (CES) as a top hydrolase candidate. Studies examined whether CES is responsible for hydrolysis and whether cellular CES expression confers prodrug sensitivity.

Pharmacogenomics of gemcitabine metabolism: functional analysis of genetic variants in cytidine deaminase and deoxycytidine kinase.

Gemcitabine (dFdC, 2',2'-difluorodeoxycytidine) is metabolized by cytidine deaminase (CDA) and deoxycytidine kinase (DCK), but the contribution of genetic variation in these enzymes to the variability in systemic exposure and response observed in cancer patients is unclear. Wild-type enzymes and variants of CDA (Lys27Gln and Ala70Thr) and DCK (Ile24Val, Ala119Gly, and Pro122Ser) were expressed in and purified from Escherichia coli, and enzyme kinetic parameters were estimated for cytarabine (Ara-C), dFdC, and its metabolite 2',2'-difluorodeoxyuridine (dFdU) as substrates. All three CDA proteins showed similar K(m) and V(max) for Ara-C and dFdC deamination, except for CDA70Thr, which had a 2.

Low-dose metronomic oral dosing of a prodrug of gemcitabine (LY2334737) causes antitumor effects in the absence of inhibition of systemic vasculogenesis.

Metronomic chemotherapy refers to the close, regular administration of conventional chemotherapy drugs at relatively low, minimally toxic doses, with no prolonged break periods; it is now showing encouraging results in various phase II clinical trials and is currently undergoing phase III trial evaluation. It is thought to cause antitumor effects primarily by antiangiogenic mechanisms, both locally by targeting endothelial cells of the tumor neovasculature and systemically by effects on bone marrow-derived cells, including circulating endothelial progenitor cells (CEP). Previous studies have shown reduction of CEPs by metronomic administration of a number of different chemotherapeutic drugs, including vinblastine, cyclophosphamide, paclitaxel, topotecan, and tegafur plus uracil (UFT).

Synthesis, crystallization, and biological evaluation of an orally active prodrug of gemcitabine.

The design, synthesis, and biological characterization of an orally active prodrug (3) of gemcitabine are described. Additionally, the identification of a novel co-crystal solid form of the compound is presented. Valproate amide 3 is orally bioavailable and releases gemcitabine into the systemic circulation after passing through the intestinal mucosa.