TAS-114, a First-in-Class Dual dUTPase/DPD Inhibitor, Demonstrates Potential to Improve Therapeutic Efficacy of Fluoropyrimidine-Based Chemotherapy.

5-Fluorouracil (5-FU) is an antimetabolite and exerts antitumor activity via intracellularly and physiologically complicated metabolic pathways. In this study, we designed a novel small molecule inhibitor, TAS-114, which targets the intercellular metabolism of 5-FU to enhance antitumor activity and modulates catabolic pathway to improve the systemic availability of 5-FU. TAS-114 strongly and competitively inhibited deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase), a gatekeeper protein preventing aberrant base incorporation into DNA, and enhanced the cytotoxicity of fluoropyrimidines in cancer cells; however, it had little intrinsic activity. In addition, TAS-114 had moderate and reversible inhibitory activity on dihydropyrimidine dehydrogenase (DPD), a catabolizing enzyme of 5-FU. Thus, TAS-114 increased the bioavailability of 5-FU when coadministered with capecitabine in mice, and it significantly improved the therapeutic efficacy of capecitabine by reducing the required dose of the prodrug by dual enzyme inhibition. Enhancement of antitumor efficacy caused by the addition of TAS-114 was retained in the presence of a potent DPD inhibitor containing oral fluoropyrimidine (S-1), indicating that dUTPase inhibition plays a major role in enhancing the antitumor efficacy of fluoropyrimidine-based therapy. In conclusion, TAS-114, a dual dUTPase/DPD inhibitor, demonstrated the potential to improve the therapeutic efficacy of fluoropyrimidine. Dual inhibition of dUTPase and DPD is a novel strategy for the advancement of oral fluoropyrimidine-based chemotherapy for cancer treatment. Mol Cancer Ther; 17(8); 1683-93. ©2018 AACR.

First-in-human, phase I dose-escalation study of single and multiple doses of a first-in-class enhancer of fluoropyrimidines, a dUTPase inhibitor (TAS-114) in healthy male volunteers.

PURPOSE: TAS-114 is a first-in-class oral deoxyuridine triphosphatase (dUTPase) inhibitor, which acts as a modulator of the pyrimidine nucleotide metabolic pathway. This was a first-in-human, phase 1 study that investigated the pharmacokinetics (PK) and safety of single-agent TAS-114 when it was given at single and multiple doses. METHODS: For the single-dose cohort (n = 25), healthy male volunteers received a single dose of TAS-114 at 6, 18, 60, 150, and 300 mg. The magnitude of dihydropyrimidine dehydrogenase (DPD) inhibition and the food effect on TAS-114 PK were also investigated. For the multiple-dose cohort (n = 10), subjects received TAS-114 for 14 days consecutively. RESULTS: In the dose-escalating single-dose cohort, the disposition of TAS-114 followed linear kinetics. The elimination half-life was approximately 2 h. The urine excretion rate and food effect were minimal. A significant increase in uracil Cmax was observed at administered doses of 150 mg or higher of TAS-114, suggesting that significant inhibition of DPD occurred at these doses. No apparent CYP3A4 auto-induction was observed in the multiple-dose cohort. No significant safety concerns at these dose levels were noted after single and multiple dosing. CONCLUSIONS: TAS-114 has shown both a favorable safety and pharmacokinetic profile after single and repeated doses. TAS-114 was considered to possess a moderate DPD inhibitory effect. These findings will facilitate clinical studies of the combination chemotherapies in cancer patients and may reduce the safety risk in the frail cancer patients.

Formation pathways of gamma-butyrolactone from the furan ring of tegafur during its conversion to 5-fluorouracil.

Tegafur (FT) is a 5-fluorouracil (5-FU) prodrug that has been clinically used for various cancer chemotherapies. The following metabolites of FT were identified in patients: 5-FU, fluoro-beta-alanine, and gamma-butyrolactone (GBL) and its acidic form, gamma-hydroxybutyrate (GHB). GBL/GHB, which is probably generated from the furan ring of FT, inhibits tumor cell angiogenesis, contributing to the antitumor effect of FT-based therapies. In the present study, we identified the metabolites formed from the furan ring of FT by CYP2A6 and thymidine phosphorylase (TPase) using 2,4-dinitrophenylhydrazine derivatization procedures and clarified the metabolic pathway of FT to GBL/GHB. Succinaldehyde (SA) and 4-hydroxybutanal (4-OH-BTL) were produced as the metabolites because of the cleavage of the furan ring of FT during its conversion to 5-FU in cDNA-expressed CYP2A6 and purified TPase, respectively; however, GBL/GHB was hardly detected in cDNA-expressed CYP2A6 and purified TPase. GBL/GHB was formed after human hepatic microsomes or cDNA-expressed CYP2A6 mixed with cytosol were incubated with FT. Furthermore, 4-OH-BTL was converted to GBL/GHB in the microsomes and cytosol. These results suggest that GBL/GHB is generated from FT through the formation of SA and 4-OH-BTL but not directly from FT. Furthermore, the amount of 5-FU and GBL/GHB formed in the hepatic S9 was markedly decreased in the presence of a CYP2A6 inhibitor, suggesting that GBL/GHB may be mainly generated through the CYP2A6-mediated formation of SA.

[A case of acute bromvalerylurea intoxication: clinical course and alteration in serum bromvalerylurea concentration].

Bromvalerylurea is one of the non-barbiturates products and has been used as analgesics and hypnotics in Japan. A 20-year-old woman was admitted to our hospital for loss of consciousness. She had a 6-month history of transient delirium and drunken gait. Physical examination revealed erythema less than thumb's head size at her face, shoulder and thigh. Neurologically, she had a state of coma and low muscle tonus. EEG showed the pattern of burst-suppression. The level of her serum chloride was not elevated. The erythema made us check up her state of acute bromvalerylurea intoxication. High blood concentration of bromvalerylurea led to diagnosis of the bromvalerylurea intoxication. The maximum value of her serum bromvalerylurea concentration was 107 microg/ml on the second hospital day, while the concentration in cerebrospinal fluid were also increased and remained for several days. She was treated with respiration control and drip infusions. She gradually improved and recovered to be alert. She was complicated severe liver dysfunction and disseminated intravascular coagulation resulting from bromvalerylurea intoxication, also treated with intensive care and gradually recovered. We should take notice to bromvalerylurea, easily available over the counter, as one of the drugs which may cause severe loss of consciousness or coma, and general complications. And if the bromvalerylurea intoxication is prospective, we should consider whether the option of gastric irrigation is available regardless of the elapsed time.

Validation of a simple liquid chromatography-tandem mass spectrometric method for the determination of propiverine hydrochloride and its N-oxide metabolite in human plasma.

A simple high-performance liquid chromatography (HPLC)-tandem mass spectrometric method has been developed for determination of propiverine hydrochloride and its metabolite, propiverine N-oxide (M-1) in human plasma using stable isotopes, propiverine hydrochloride-d10 and M-1-d10, as internal standards. The analytes were extracted with dichloromethane from 0.2 ml of plasma in neutral condition (pH 7.0) and separated by HPLC on a C18 reversed-phase column using methanol-1% acetic acid (50:50) as a mobile phase, and detected using positive electrospray ionization in selected reaction monitoring (SRM) mode. The method was validated over a concentration range of 2-500 ng/ml for propiverine hydrochloride and 4-1000 ng/ml for M-1 using 0.2 ml of human plasma per assay. The method developed was successfully applied to analysis of propiverine hydrochloride and M-1 in clinical studies.

Vertical ophthalmoplegia in a demented patient with striatopallidodentate calcification.

A case is presented here of a 73-year-old man who showed signs of dementia, supranuclear vertical ophthalmoplegia, pseudobulbar palsy, axial dystonia, mild rigidity, and parkinsonian gait. Computed tomography of the head revealed symmetrical calcification in the striatum, globus pallidus and dentate nucleus to an extraordinary degree. No metabolic conditions were observed that could explain the intracranial calcification. Oral administration of levodopa improved the patient's motor symptoms to some extent. Ophthalmoplegia, parkinsonism and dementia combined are typically seen in patients with progressive supranuclear palsy. However, the present case and a few others that have been reported would seem to indicate that these unique symptoms might also be found in patients with intracranial calcification.

Determination of 3'-C-ethynylcytidine in human plasma and urine by liquid chromatographic-electrospray ionization tandem mass spectrometry.

A liquid chromatographic-electrospray ionization tandem mass spectrometric (LC-ESI/MS/MS) method was developed for the quantitative analysis of a novel anticancer drug, 3'-C-ethynylcytidine (I) in human plasma and urine. I and its stable isotope-labeled internal standard (II) were extracted from human plasma and urine samples using a polymer-based cation-exchange cartridge, and LC-ESI/MS/MS analysis was performed by monitoring the positive fragment ions of I and II. The linear ranges are 1-500 ng/ml in plasma and 10-5000 ng/ml in urine. The limits of quantitation for I were 1 ng/ml in plasma and 10 ng/ml in urine. The relative errors (RE) for I ranged from -8.4 to 3.0% in plasma and from 0.8 to 4.4% in urine. The relative standard deviations (RSD) for I ranged from 1.2 to 8.9% in plasma and from 0.7 to 2.8% in urine. This validated analytical method is demonstrated to be useful for the analysis of I in human plasma and urine in clinical studies.