Towards a test to predict 5-fluorouracil toxicity: Pharmacokinetic data for thymine and two sequential metabolites following oral thymine administration to healthy adult males

Plasma-Induced Changes in the Metabolome Following Vistula Tart Cherry Consumption

Evidence suggests that tart cherry (TC) supplementation has beneficial effects on health indices and recovery following strenuous exercise. However, little is known about the mechanisms and how TC might modulate the human metabolome. The aim of this study was to evaluate the influence of an acute high- and low-dose of Vistula TC supplementation on the metabolomic profile in humans. In a randomised, double-blind, placebo controlled, cross-over design, 12 healthy participants (nine male and three female; mean ± SD age, stature, and mass were 29 ± 7 years old, 1.75 ± 0.1 m, and 77.3 ± 10.5 kg, respectively) visited the laboratory on three separate occasions (high dose; HI, low dose; LO, or placebo), separated by at least seven days. After an overnight fast, a baseline venous blood sample was taken, followed by consumption of a standardised breakfast and dose conditions (HI, LO, or placebo). Subsequent blood draws were taken 1, 2, 3, 5, and 8 h post consumption. Following sample preparation, an untargeted metabolomics approach was adopted, and the extracts analysed by LCMS/MS. When all time points were collated, a principal component analysis showed a significant difference between the conditions (p < 0.05), such that the placebo trial had homogeneity, and HI showed greater heterogeneity. In a sub-group analysis, cyanidine-3-O-glucoside (C3G), cyanidine-3-O-rutinoside (C3R), and vanillic acid (VA) were detected in plasma and showed significant differences (p < 0.05) following acute consumption of Vistula TC, compared to the placebo group. These results provide evidence that phenolics are bioavailable in plasma and induce shifts in the metabolome following acute Vistula TC consumption. These data could be used to inform future intervention studies where changes in physiological outcomes could be influenced by metabolomic shifts following acute supplementation.

Role of molecularly imprinted hydrogels in drug delivery - A current perspective

Molecular imprinting in hydrogels crafts memory for template molecules in a flexible macromolecular structure. Molecular imprinting can control the pattern of the drug release via different mechanistic pathways which may involve swelling, which releases the drug via diffusion or receptive-swollen networks. Responsive hydrogels or smart hydrogels can be tailored to undergo a change in the network structure in response to a stimulus by inserting specific chemical or biological entities along their backbone polymer chains. The stimuli which can be either physical, chemical or biochemical in nature, may impact at various energy levels thereby initiating the molecular interactions at critical onset points. Conventional hydrogels lack in responding to an external stimuli in a swift manner, hence the molecular imprinting technology can significantly advance the therapeutic efficiency of the drugs with anticipated controlled release and targeting efficiency. Molecular imprinting in hydrogels is thus anticipated as a step towards establishment of drug delivery systems by providing improved delivery profiles or longer release times and deliver the drugs in a feedback regulated way. The review article focuses on the current scenario of molecularly imprinted hydrogels with emphasis on the imprinting strategies within hydrogels and challenges encountered, latent translational applications, and future perspectives.

Current status and future outlooks on therapeutic drug monitoring of fluorouracil

INTRODUCTION

: Therapeutic drug monitoring (TDM) of the anticancer drug fluorouracil (5FU) as a method to support dose adjustments has been researched and discussed extensively. Despite manifold evidence of the advantages of 5FU-TDM, traditional body surface area (BSA)-guided dosing is still widely applied.

AREAS COVERED

: This review covers the latest evidence on 5FU-TDM based on a literature search in PubMed between June and September 2021. It particularly highlights new approaches of implementing 5FU-TDM into precision medicine by combining TDM with pharmacogenetic testing and/or pharmacometric models. This review further discusses remaining obstacles in order to incorporate 5FU-TDM into clinical routine.

EXPERT OPINION

: New data on 5FU-TDM further strengthen the advantages compared to BSA-guided dosing as it is able to reduce pharmacokinetic variability and thereby improve treatment efficacy and safety. Interprofessional collaboration has the potential to overcome the remaining barriers for its implementation. Pre-emptive pharmacogenetic testing followed by 5FU-TDM can further improve 5FU exposure in a substantial proportion of patients. Developing a model framework integrating pharmacokinetics and pharmacodynamics of 5FU will be crucial to fully advance into the precision medicine era. Model applications can potentially support clinicians in dose finding before starting chemotherapy. Additionally, TDM provides further assistance in continuously improving model predictions.

Association between Metabolic Syndrome Components and Cardiac Autonomic Modulation among Children and Adolescents: A Systematic Review and Meta-Analysis

Simple Summary

The clustering of metabolic syndrome (MetS) risk factors is becoming more prevalent in young people (up to the age of 19 years) leading to the development of type 2 diabetes (T2D) and cardiovascular diseases in early adulthood. The impact of MetS risk factors on cardiac autonomic modulation (CAM) or vice versa have been noted to track from childhood to pre-adolescence and adolescence. Understating associations in this age group may help improve the clinical outcomes of the MetS, even when MetS symptoms are not visible. Potential damage from each individual MetS component and the ability to predict early cardiac damage or upcoming cardiovascular events is very important. Therefore, the present systematic review and meta-analysis investigated the associations between CAM and MetS risk factors individually to verify which MetS risk components were significantly correlated with which heart rate variability (HRV) indices before or at the onset of the MetS among young people. The purpose of this review was to outline the importance of potentially screening HRV indices in young people even with only one MetS risk factor, as a pre-indicator for early cardiovascular risk stratification. Cross-sectional studies that examined the relationship of MetS risk factors with HRV indices were searched using four databases including PubMed, the Cochrane clinical trials library, Medline and the Web of Science. Correlation coefficients with 95% confidence intervals (95% CI), and random effects meta-analyses of the association between MetS risk factors with HRV indices were performed. Our results propose that lipid profiles including high density lipoprotein (HDL) and triglycerides (TGs), waist circumference (WC) and blood pressure (BP) are associated with CAM in young people up to the age of 19 years. The use of HRV indices to predict future MetS risk, and relationships with individual risk factors including HDL, BP, WC and TGs, were established. Furthermore, arterial pressure, respiration, stress and physical activity must be taken into consideration for future studies along with CAM related to young people (up to the age of 19 years), and it is recommended to explore further the associations reported here, as CAM is not the only determinant of neurovisceral regulation.

Abstract

Background: the clustering of metabolic syndrome (MetS) risk factors is becoming more prevalent in children, leading to the development of type 2 diabetes (T2D) and cardiovascular diseases in early adulthood. The impact of MetS risk factors on cardiac autonomic modulation (CAM) or vice versa has been noted to track from childhood to pre-adolescence and adolescence. Understating associations in this age group may help to improve the clinical outcomes of the MetS, even when MetS symptoms are not visible. Potential damage from each individual MetS component and the ability to predict early cardiac damage or upcoming cardiovascular events is very important. Therefore, the present systematic review and meta-analysis investigated the associations between CAM and MetS risk factors individually to verify which of the MetS risk components were significantly correlated with heart rate variability (HRV) indices before or at the onset of the MetS among young people. The purpose of this review was to outline the importance of potentially screening HRV indices in young people even with only one MetS risk factor, as a pre-indicator for early cardiovascular risk stratification. Methods: cross-sectional studies that examined the relationship of MetS risk factors with HRV indices were searched using four databases including PubMed, the Cochrane clinical trials library, Medline and the Web of Science. Correlation coefficients with 95% confidence intervals (95% CI), and random effects meta-analyses of the association between MetS risk factors with HRV indices were performed. Results: out of 14 cross-sectional studies and one case-control study, 8 studies (10 data sets) provided association data for the meta-analysis. Our results indicated significant positive correlations for systolic blood pressure (SBP) (correlation coefficient 0.13 (95%CI: 0.06; 0.19), I² = 47.26%) and diastolic blood pressure (DBP) (correlation coefficient 0.09 (95%CI: −0.01; 0.18), I² = 0%) with a Low Frequency/High Frequency ratio (LF/HF). Significant negative correlations for waist circumference (WC) (correlation coefficient −0.12 (95%CI: −0.19; −0.04), I² = 51.50%), Triglycerides (TGs) (correlation coefficient −0.09 (95%CI: −0.15; −0.02), I² = 0%) and ≥2 MetS risk factors (correlation coefficient −0.10 (95%CI: −0.16; −0.03), I² = 0%); with high frequency (HF) were revealed. Significant positive correlations for high density lipoprotein (HDL) (correlation coefficient 0.08 (95%CI: 0.05; 0.11), I² = 0%) and significant negative correlations of ≥2 MetS risk (correlation coefficient −0.04 (95%CI: −0.12; 0.03), I² = 0.0%) with low frequency (LF) were revealed. Significant negative correlations for TGs (correlation coefficient −0.09 (95%CI: −0.23; 0.05), I² = 2.01%) with a mean square root of the sum of differences between mean time between two successive intervals (rMSSD) and significant positive correlation of HDL (correlation coefficient 0.09 (95%CI: −0.01; 0.19), I² = 0.33%) with standard deviation of the time between two successive intervals (SDNN) were also revealed. An Egger’s test indicated that there was no obvious publication bias for any of the above relationships except for TGs and rMSSD. The significance level stipulated for the meta-analysis was p < 0.05. Conclusions: lipid profiles (HDL and TGs), WC and BP were associated with CAM in young people up to the age of 19 years. The use of HRV indices to predict future MetS risk, and relationships with individual risk factors including HDL, BP, WC and TGs, were established. Future studies related to young people (up to the age of 19 years) are recommended to explore the associations reported here further.

Comparison of a thymine challenge test and endogenous uracil-dihydrouracil levels for assessment of fluoropyrimidine toxicity risk

PURPOSE

Standard dosages of fluoropyrimidine chemotherapy result in severe toxicity in a substantial proportion of patients, however, routine pre-therapeutic toxicity prediction remains uncommon. A thymine (THY) challenge test can discriminate risk of severe gastrointestinal toxicity in patients receiving fluoropyrimidine monotherapy. We aimed to measure endogenous plasma uracil (U) and its ratio to dihydrouracil (DHU), and assess the performance of these parameters compared with the THY challenge test to evaluate risk of severe toxicity.

METHODS

Plasma samples, previously collected from 37 patients receiving 5-fluorouracil (5-FU) or capecitabine monotherapy for a THY challenge test (ACTRN12615000586516; retrospectively registered), were assessed for endogenous plasma concentrations of U and DHU using a validated LC-MS/MS method. Renal function was estimated from blood creatinine, and patients with ≥ grade 3 toxicity (CTCAE v4.0) were classified as cases.

RESULTS

There were no differences in median endogenous U plasma concentrations or U/DHU ratios between severe toxicity cases and non-cases. Significant differences between cases and non-cases were noted when these measures were normalised to the estimated renal function (CrCL), U_norm p = 0.0004; U/DHU_norm p = 0.0083. These two parameters had a sensitivity of 29%, compared with 57% for the THY challenge test in the same patients. Genotyping for clinically relevant DPYD variants was inferior to either of these pyrimidine phenotyping tests (sensitivity of 14%).

CONCLUSIONS

The endogenous uracil-based parameters, adjusted to CrCL, were more predictive of increased risk of severe fluoropyrimidine toxicity than DPYD genotyping. However, endogenous U measurement detected fewer cases of severe toxicity than the THY challenge test.

5-Fluorouracil Response Prediction and Blood Level-Guided Therapy in Oncology: Existing Evidence Fundamentally Supports Instigation

5-Fluorouracil (5-FU) response prediction and therapeutic drug monitoring (TDM) are required to minimize toxicity while preserving efficacy. Conventional 5-FU dose normalization uses body surface area. It is characterized by up to 100-fold interindividual variability of pharmacokinetic (PK) parameters, and typically >50% of patients have plasma 5-FU concentrations outside the optimal range. This underscores the need for a different dose rationalization paradigm, hence there is a case for 5-FU TDM. An association between 5-FU PK parameters and efficacy/toxicity has been established. It is believed that 5-FU response is enhanced and toxicity is reduced by PK management of its dosing. The area under the concentration-time curve is the most relevant PK parameter associated with 5-FU efficacy/toxicity, and optimal therapeutic windows have been proposed. Currently, there is no universally applied a priori test for predicting 5-FU response and identifying individuals with an elevated risk of toxicity. The following two-step strategy: prediction of response/toxicity and TDM for subsequent doses seems plausible. Approximately 80% of 5-FU is degraded in a three-step sequential metabolic pathway. Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme. Its deficiency can cause toxicity with standard 5-FU doses. DPD also metabolizes uracil (U) into 5,6-dihydrouracil (UH2). The UH2/U ratio is an index of DPD activity and a credible biomarker of response and toxicity. This article outlines the UH2/U ratio as a parameter for 5-FU response/toxicity prediction and highlights key studies emphasizing the value of 5-FU TDM. Broad application of 5-FU response/toxicity prediction and blood level-guided therapy remains unmet, despite ever-increasing clinical interest. Considered collectively, existing evidence is compelling and fundamentally supports universal instigation of response/toxicity prediction and TDM.

Feature of Heart Rate Variability and Metabolic Mechanism in Female College Students with Depression

Purpose

To explore the effects of depression on cardiac autonomic nerve function and related metabolic pathways, the heart rate variability (HRV) and urinary differential metabolites were detected on the college students with depression.

Methods

12 female freshmen with depression were filtered by the Beck Depression Inventory (BDI-II) and Self-rating Depression Scale (SDS). By wearing an HRV monitoring system, time domain indexes and frequency domain indexes were measured over 24 hours. Liquid chromatography–mass spectrometry (LC-MS) was used to detect their urinary differential metabolites. Differential metabolites were identified by principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA). The metabolic pathways related to these differential metabolites were analyzed by the MetPA database.

Results

Stress time was significantly increased, and recovery time was markedly decreased in the depression group compared with the control group (p < 0.001). Standard deviation of the normal-to-normal R interval (SDNN), root mean square of the beat-to-beat differences (RMSSD), high frequency (HF), and low frequency (LF) were decreased significantly (p < 0.001). Standard deviation of the normal-to-normal R interval (SDNN), root mean square of the beat-to-beat differences (RMSSD), high frequency (HF), and low frequency (LF) were decreased significantly (

Conclusion

Some autonomic nervous system disruption, high stress, and poor fatigue recovery were confirmed in college students with depression. The metabolic mechanism involved the disruption of coenzyme Q biosynthesis, glycine-serine-threonine metabolism, tyrosine metabolism, pyrimidine metabolism, and steroid metabolism under daily stress.

A case-control study to assess the ability of the thymine challenge test to predict patients with severe to life threatening fluoropyrimidine-induced gastrointestinal toxicity

AIMS

A previous study suggested that a thymine (THY) challenge dose could detect aberrant pharmacokinetics in known cases of fluoropyrimidine toxicity compared with healthy volunteers. The preliminary data suggested that urine sampling also could detect this aberrant disposition. The aim of this case-control study was to assess the ability of the urinary THY challenge test to discriminate cases of severe gastrointestinal toxicity in a cohort of patients treated with 5-fluorouracil or capecitabine.

METHODS

Patients (n = 37) received a 250 mg (per os) dose of THY and a cumulative urine sample was collected for 0-4 h. The urinary amounts of THY and metabolite dihydrothymine (DHT) were determined by liquid chromatography/mass spectrometry. Genomic DNA was analysed for DPYD gene variants. Renal function was estimated from blood creatinine levels. Cases (n = 9) and noncases (n = 23) of severe (grade ≥ 3) gastrointestinal toxicity were defined based on Common Terminology Criteria for Adverse Events.

RESULTS

The median THY/DHT ratios were 6.2 (interquartile range 2.9-6.4) in cases, including the 2 patients who were DPYD heterozygous carriers. However, this was not significantly different (P = .07) from the THY/DHT in noncases (median 2.6, interquartile range 2.8-4.2). Although creatinine clearance was lower (P = .001) in cases, renal function could not discriminate cases from noncases. However, logistic regression analysis using both of these explanatory variables could discriminate most cases (receiver operating characteristic area 0.8792, 95% confidence interval 0.72-1.00).

CONCLUSIONS

The THY challenge test combined with a patient's renal function may be useful as a phenotypic diagnostic test to detect risk of life-threatening fluoropyrimidine gastrointestinal toxicity.

Preliminary Evidence for Enhanced Thymine Absorption: A Putative New Phenotype Associated With Fluoropyrimidine Toxicity in Cancer Patients

BACKGROUND

Chemotherapy for colorectal, head and neck, and breast cancer continues to rely heavily on 5-fluorouracil and its oral prodrug capecitabine. Associations of serious fluoropyrimidine adverse effects have focused on inherited deficiency of the catabolic enzyme, dihydropyrimidine dehydrogenase. However, abnormal dihydropyrimidine dehydrogenase activity accounts for only about one-third of observed toxicity cases. Thus, the cause of most fluorouracil toxicity cases remains unexplained.

METHODS

For this small cohort study, thymine (THY) 250 mg was administered orally to 6 patients who had experienced severe toxicity during treatment with 5FU or capecitabine. Plasma and urine were analyzed for THY and its catabolites dihydrothymine (DHT) and β-ureidoisobutyrate.

RESULTS

Of the 6 patients, 2 had decreased THY elimination and raised urinary THY recovery consistent with inherited partial dihydropyrimidine dehydrogenase deficiency, confirmed by DPYD sequencing. Unexpectedly, 3 patients displayed grossly raised plasma THY concentrations but normal elimination profiles (compared with a normal range for healthy volunteers previously published by the authors). DPYD and DPYS sequencing of these 3 patients did not reveal any significant loss-of-activity allelic variants. The authors labeled the phenotype in these 3 patients as "enhanced thymine absorption". Only 1 of the 6 cases of toxicity had a normal postdose plasma profile for THY and its catabolites. Postdose urine collections from all 6 patients had THY/DHT urinary ratios above 4.0, clearly separated from the ratios in healthy subjects that were all below 3.0.

CONCLUSIONS

This small cohort provided evidence for a hypothesis that fluorouracil toxicity cases may include a previously undescribed pyrimidine absorption variant, "enhanced thymine absorption," and elevated THY/DHT ratios in urine may predict fluorouracil toxicity. A prospective study is currently being conducted.

Molecularly imprinted polymers based drug delivery devices: a way to application in modern pharmacotherapy. A review

This review presents the current status of molecularly imprinted polymers (MIPs) for drug delivery, in particular the studies that focus on biocompatibility, cytotoxicity, and in vitro or in vivo behavior of MIPs. It also shows the limitations that hamper the introduction of MIPs to pharmacotherapy and prevent this class of polymers from commercialization. MIPs are promising materials in the construction of drug delivery devices because they can provide improved delivery profiles or longer release times and deliver the drugs in the feedback regulated way, which is extremely important in modern pharmacotherapy. Here, a brief overview of the imprinting process and a concise description of drug release mechanisms from the imprinted materials will be presented followed by the discussion of potential MIP drug delivery devices for ocular, dermal, intravenous and oral routes of administration. Finally, future prospects for imprinted drug delivery forms will be outlined.

Preparation and evaluation of a novel anticancer drug delivery carrier for 5-Fluorouracil using synthetic bola-amphiphile based on lysine as polar heads

A novel bolaamphiphile surfactant N,N'-(dodecane-1, 12-diyl) bis (2,6-diaminohexanamide) (DADL) was designed and synthesized using l-lysine and 1,12-diaminododecane as the hydrophilic and hydrophobic part, respectively. After separation and purification, the structure of the synthetic bolaamphiphile surfactant was verified by FTIR, MS and ¹H NMR. The synthetic bolaamphiphile was able to self-assemble to form vesicles. After formulation screening, vesicles loaded with 5-Fluorouracil (5-Fu) were prepared with Tween 60 and DADL by sonication and were examined by dynamic light scattering and transmission electron microscopy. Micro-FTIR was applied to investigate the conformation of the bola molecules within the vesicle membrane. The release profile of the vesicles showed a pH-sensitive and sustained release. No significant toxicity was observed in an in vitro cell viability assay. The antitumor efficacy of the 5-Fu-loaded vesicles on H₂₂ tumor-bearing mice was remarkably high due to the EPR effects. These results show that our novel bolaamphiphile derived from lysine has excellent potential as a pH-sensitive drug carrier.

Repeated cycles of 5-fluorouracil chemotherapy impaired anti-tumor functions of cytotoxic T cells in a CT26 tumor-bearing mouse model

Background

Recently, the immunostimulatory roles of chemotherapeutics have been increasingly revealed, although bone marrow suppression is still a common toxicity of chemotherapy. While the numbers and ratios of different immune subpopulations are analyzed after chemotherapy, changes to immune status after each cycle of treatment are less studied and remain unclear.

Results

To determine the tumor-specific immune status and functions after different cycles of chemotherapy, we treated CT26 tumor-bearing mice with one to four cycles of 5-fluorouracil (5-FU). Overall survival was not improved when more than one cycle of 5-FU was administered. Here we present data concerning the immune statuses after one and three cycles of chemotherapy. We analyzed the amount of spleen cells from mice treated with one and three cycles of 5-FU as well as assayed their proliferation and cytotoxicity against the CT26 tumor cell line. We found that the absolute numbers of CD8 T-cells and NK cells were not influenced significantly after either one or three cycles of chemotherapy. However, after three cycles of 5-FU, proliferated CD8 T-cells were decreased, and CT26-specific cytotoxicity and IFN-γ secretion of spleen cells were impaired in vitro. After one cycle of 5-FU, there was a greater percentage of tumor infiltrating CD8 T-cells. In addition, more proliferated CD8 T-cells, enhanced tumor-specific cytotoxicity as well as IFN-γ secretion of spleen cells against CT26 in vitro were observed. Given the increased expression of immunosuppressive factors, such as PD-L1 and TGF-β, we assessed the effect of early introduction of immunotherapy in combination with chemotherapy. We found that mice treated with cytokine induced killer cells and PD-L1 monoclonal antibodies after one cycle of 5-FU had a better anti-tumor performance than those treated with chemotherapy or immunotherapy alone.

Conclusions

These data suggest that a single cycle of 5-FU treatment promoted an anti-tumor immune response, whereas repeated chemotherapy cycles impaired anti-tumor immune functions. Though the amount of immune cells could recover after chemotherapy suspension, their anti-tumor functions were damaged by multiple rounds of chemotherapy. These findings also point towards early implementation of immunotherapy to improve the anti-tumor effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-016-0167-7) contains supplementary material, which is available to authorized users.

In vitro/in vivo study of novel anti-cancer, biodegradable cross-linked tannic acid for fabrication of 5-fluorouracil-targeting drug delivery nano-device based on a molecular imprinted polymer

The structure of a 5-fluorouracil carrier and fluorescent image of an animal after injection under a magnetic field.