Population pharmacokinetic and pharmacodynamic modeling of capecitabine and its metabolites in breast cancer patients

PURPOSE

The present study was performed to examine relationships between systemic exposure of capecitabine metabolites (5-FU, 5'-DFCR and 5'-DFUR) and toxicity or clinical response in patients with metastatic breast cancer.

METHODS

A population pharmacokinetic model for capecitabine and its three metabolites was built. Typical parameter values, characteristics of random distributions, associated with parameters, and covariates impact were estimated. Area under the curve (AUC) were computed for 5-FU and compared with grades of toxicity. Pharmacokinetic modeling was based on data collected on the first treatment cycle. Toxicity was assessed on the two first treatment cycles.

RESULTS

The study was conducted in 43 patients. The population pharmacokinetic model (a one-compartment model per compound) was able to capture the very complex absorption process of capecitabine. Statistically significant covariates were cytidine deaminase, alkaline phosphatase and dihydrouracilemia (UH2)/uracilemia (U) ratio. UH2/U ratio was the most significant covariate on 5-FU elimination and CDA on the transformation of 5'-DFCR in 5'-DFUR. A trend was observed between 5-FU AUC and thrombopenia toxicity grades, but not with other toxicities. Best clinical response was not linked to systemic exposure of capecitabine metabolites.

CONCLUSION

In our study, we propose a model able to describe, meanwhile, and its main metabolites, with a complex absorption process and inclusion of enzyme activity covariates such as CDA and UH2/U ratio. Trial registration Eudract 2008-004136-20, 2008/11/26.

Successful management of hyperammonemia with hemodialysis on day 2 during 5-fluorouracil treatment in a patient with gastric cancer: a case report with 5-fluorouracil metabolite analyses

Purpose

Hyperammonemia is an important adverse event associated with 5-fluorouracil (5FU) from 5FU metabolite accumulation. We present a case of an advanced gastric cancer patient with chronic renal failure, who was treated with 5FU/leucovorin (LV) infusion chemotherapy (2-h infusion of LV and 5FU bolus followed by 46-h 5FU continuous infusion on day 1; repeated every 2 weeks) and developed hyperammonemia, with the aim of exploring an appropriate hemodialysis (HD) schedule to resolve its symptoms.

Methods

The blood concentrations of 5FU and its metabolites, α-fluoro-β-alanine (FBAL), and monofluoroacetate (FA) of a patient who had hyperammonemia from seven courses of palliative 5FU/LV therapy for gastric cancer were measured by liquid chromatography–mass spectrometry.

Results

On the third day of the first cycle, the patient presented with symptomatic hyperammonemia relieved by emergency HD. Thereafter, the 5FU dose was reduced; however, in cycles 2–4, the patient developed symptomatic hyperammonemia and underwent HD on day 3 for hyperammonemia management. In cycles 5–7, the timing of scheduled HD administration was changed from day 3 to day 2, preventing symptomatic hyperammonemia. The maximum ammonia and 5FU metabolite levels were significantly lower in cycles 5–7 than in cycles 2–4 (NH3 75 ± 38 vs 303 ± 119 μg/dL, FBAL 13.7 ± 2.5 vs 19.7 ± 2.0 μg/mL, FA 204.0 ± 91.6 vs 395.9 ± 12.6 ng/mL, mean ± standard deviation, all p < 0.05). After seven cycles, partial response was confirmed.

Conclusion

HD on day 2 instead of 3 may prevent hyperammonemia in 5FU/LV therapy.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04158-1) contains supplementary material, which is available to authorized users.

High-throughput method to analyze tegafur and 5-fluorouracil in human tears and plasma using hydrophilic interaction liquid chromatography/tandem mass spectrometry

RATIONALE

We developed a new high-throughput method to analyze tegafur (FT) and 5-fluorouracil (5-FU) in tear and plasma samples using hydrophilic interaction liquid chromatography (HILIC)/tandem mass spectrometry (MS/MS).

METHODS

The tear samples (10 μL) spiked with FT, 5-FU, and 5-chlorouracil (internal standard) were diluted using 40 μL of 2 M ammonium acetate and 250 μL of acetonitrile with 2% formic acid; 20 μL of plasma spiked with the two drugs and internal standard was diluted with 80 μL of 2 M ammonium acetate and 500 μL of acetonitrile with 2% formic acid. After centrifugation, the clear supernatant extract (15 μL) was directly injected into the HILIC/MS/MS instrument, and each drug was separated on a Unison UK-Amino column (50 mm × 3 mm i.d., 3 μm particle size) with a linear gradient elution system composed of 10 mM ammonium acetate (pH 6.8) and acetonitrile at a flow rate of 0.7 mL/min. We performed quantification by multiple reaction monitoring (MRM) with negative-ion atmospheric-pressure chemical ionization.

RESULTS

Distinct peaks were observed for the drugs on each MRM channel within 2 min. The regression equations showed good linearity within the range 0.04-4.0 μg/mL for the tear and plasma samples with detection limits at 0.02-0.04 μg/mL. Recoveries for target analytes (FT and 5-FU) for the tear and plasma samples were in the 94-128% and 94-104% ranges, respectively. The intra- and inter-day coefficients of variation for the two drugs were lower than 10.8%. The accuracies of quantitation were 97-115% for both samples.

CONCLUSIONS

We established a high-throughput, reproducible, and practical procedure for analyzing FT and 5-FU in human tear and plasma samples using HILIC/MS/MS analysis with an aminopropyl-bonded mixed-mode separation column. This method can be applied to the high-throughput routines used in clinical analyses.

The Herb-Drug Pharmacokinetic Interaction of 5-Fluorouracil and Its Metabolite 5-Fluoro-5,6-Dihydrouracil with a Traditional Chinese Medicine in Rats

Background: Xiang-Sha-Liu-Jun-Zi-Tang (XSLJZT) is the most common traditional formula given to colorectal and breast cancer patients in Taiwan, according to a statistical study of the National Health Insurance Research Database. 5-Fluorouracil (5-FU) is widely used as the first line of treatment for colorectal cancer. Thus, the aim of study is to investigate the pharmacokinetic interaction of XSLJZT and 5-FU. Methods: To investigate the herb–drug interaction of XSLJZT with 5-FU as well as its metabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) using pharmacokinetics, a high-performance liquid chromatography (HPLC) system coupled with a photodiode array detector was developed to monitor 5-FU and 5-FDHU levels in rat blood. Rats were divided into three cohorts, one of which was administered 5-FU (100 mg/kg, iv—intravenous) alone, while the other two groups were pretreated with low and high doses of XSLJZT (600 mg/kg/day or 2400 mg/kg/day for 5 consecutive days) in combination with 5-FU. Results: The results demonstrated that 5-FU level was not significantly different between the group treated with only 5-FU and the group pretreated with a normal dose of XSLJZT (600 mg/kg/day). However, pharmacokinetic analysis revealed that pretreatment with a high dose of XSLJZT (2400 mg/kg/day) extended the residence time and increased the volume of distribution of 5-FU. No significant distinctions were found in 5-FDHU pharmacokinetic parameters at three doses of XSLJZT. Conclusions: Overall, the pharmacokinetic results confirm the safety of coadministering 5-FU with XSLJZT, and provide practical dosage information for clinical practice.

REVERSE PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR DETERMINATION OF 5-FLUOROURACIL IN RABBIT PLASMA

A simple, efficient, accurate and selective HPLC method has been developed and validated successfully for the estimation of 5-fluorouracil in rabbit plasma. The drug was eluted by using Supelco C18 column (1.5 cm x 4.6 mm, 5 μm) with a mobile phase consisting of methanol and water (20: 80, v/v) by adjusting pH at 3.2, using perchloric acid solution. The retention time was found to be 4.107 with a flow rate of I mL/min. Multiple validation parameters evaluated with high accuracy indicating that the current method sufficiently qualifies the recommended criteria. Regression value obtained from linearity curve was R² = 0.999 and percentage recovery obtained was ranged from 96.6 to 102.5%. A fine response in short run time with perfect resolution made the method highly suitable for pharmacokinetic studies.

Determining the optimal 5-FU therapeutic dosage in the treatment of colorectal cancer patients

Fluorouracil (5-FU) has been wildly used as a primary medication in the treatment of solid tumors including colorectal cancer. The treatment efficacy and toxicity of 5-FU varies greatly among individuals, suggesting a need for individualized regimen for cancer patients. The present study analyzed the blood concentration of 5-FU and its therapeutic efficacy and toxicity, evaluated the relationship of AUC (area under the plasma concentration-time curve), and the protein expression of DPD (dihydropyrimidine dehydrogenase) and TS (thymidylate synthetase), and therapeutic efficacy and toxicity. It was found that the AUC of 5-FU was 34.16±14.83mgmg·h/L in this cohort of study. The immunohistochemical analysis revealed 38.96% and 81.82% positive staining for DPD and TS in colorectal cancer tissues, respectively. We demonstrated that the expression of TS is positively correlated with the expression of DPD. There was a positive correlation between AUC and therapeutic efficacy, and gastrointestinal tract and neural toxicity. The expression of neither DPD nor TS had significant correlations with therapeutic efficacy and toxicity. Based on the blood 5-FU concentration and its relationship with treatment efficacy and toxicity, we determined an optimal therapeutic dosage of 5-FU to be equivalent to an AUC=28.03-38.94mgmg·h/L. Our study will be helpful in providing an individualized medical regimen for the treatment of colorectal cancer patients.

LC-MS/MS assay for the quantitation of FdCyd and its metabolites FdUrd and FU in human plasma

The hypomethylating agent 5-fluoro-2'-deoxycytidine (FdCyd, NSC 48006) is being evaluated clinically both via the intravenous route and via the oral route in combination with 3,4,5,6-tetrahydrouridine (THU), a potent inhibitor of FdCyd catabolism. To determine the pharmacokinetics of FdCyd and downstream metabolites, we developed and validated an LC-MS/MS assay for the quantitation of FdCyd, 5-fluoro-2'-deoxyuridine (FdUrd), and 5-fluorouracil (FU) in 0.2mL human plasma. After acetonitrile protein precipitation, the sample was split and separate chromatography was achieved for FdCyd with a Synergi Polar-RP column and for FdUrd and FU with a Shodex Asahipak NH2P-50 2D column. Gradients of 0.1% acetic acid in acetonitrile and water were used. Detection with a Quattromicro quadrupole mass spectrometer with electrospray ionization in positive-ion (FdCyd) or negative-ion (FdUrd and FU) multiple reaction monitoring (MRM) mode. The assay was linear from 5 to 3000ng/mL for all three analytes and proved to be accurate (96.7-105.5%) and precise (<8.1%CV), and fulfilled FDA criteria for bioanalytical method validation. We demonstrated the suitability of this assay for measuring FdCyd and metabolites FdUrd and FU in plasma from a patient who was administered 120mg PO FdCyd 30min after 3000mg THU. Our LC-MS/MS assay will be an essential tool to further define the pharmacology of FdCyd in ongoing and future studies.

[Review of pharmacokinetic monitoring of 5-Fluorouracil as a tool to increase efficacy and safety]

Recent progress in medical knowledge has indicated that both clinical and biological markers will determine the response to different medical treatments: age, gender and genetics will determine the success of treatment. Genetic variability in this respect is fundamental and determines efficiency and safety of drugs, as well as susceptibility and illness' development. Fortunately, personalized medicine now offers individually tailored treatment strategies for each patient's needs. This is of outmost importance in oncology, since treatment is per se toxic and the commonly found low serum drug concentrations result in low treatment efficacy. Personalized medicine will allow a better approach to this, until now, a poorly managed disease. In this review we intent to raise awareness of personalized medicine and of clinical pharmacologic monitoring, with the aim to achieve adequate levels of efficacy and safety in the use of the cytotoxic drug 5-Fluorouracil (5-FU). Additionally, the importance of pharmacogenomics for the use of 5-FU is discussed. We designed this discussion towards medical practitioners challenged with treatment decisions every day, together with their patients.

Fluctuation in Plasma 5-Fluorouracil Concentration During Continuous 5-Fluorouracil Infusion for Colorectal Cancer

BACKGROUND/AIM

It is generally believed that the plasma concentration of 5-fluorouracil (5-FU) is constant when 5-FU is continually administered for chemotherapy. The aim of the present study was to verify whether this is true.

PATIENTS AND METHODS

Nine patients with colorectal cancer were enrolled in this study. All patients received chemotherapy; four patients received FOLFIRI (leucovorin, 5-fluorouracil, irinotecan) and five received FOLFOX (leucovorin, 5-fluorouracil, oxaliplatin). 5-FU was administered continuously (2400 mg/m(2)) for 46 h. Serum was collected at 12 points after the start of administration. The concentration of 5-FU was evaluated using a new immunoassay method and gas chromatography-mass spectrometric (GC/MS) method.

RESULTS

The concentrations of 5-FU fluctuated dramatically over time, with greater than 3-fold changes in each individual, and the pattern was not constant.

CONCLUSION

Because the serum concentration of 5-FU fluctuates and displays various patterns, the dosage should not be based on body surface area. A new individualized method for determining the 5-FU dosage should be developed.

5-Fluorouracil Chemotherapy for Dihydropyrimidine Dehydrogenase-deficient Patients: Potential of the Dose-escalation Method

BACKGROUND

Dihydropyrimidine dehydrogenase (DPD) degrades approximately 85% of administered 5-fluorouracil (5-FU). With a reported high mortality rate, chemotherapy is generally contraindicated for patients with DPD deficiency.

PATIENTS AND METHODS

Chemotherapy was initiated for a 73-year-old man with DPD deficiency. Capecitabine was administered in incrementally increasing doses, beginning with a single pill while monitoring plasma 5-FU concentration, and neutrophil and platelet counts.

RESULTS

DPD protein level was 2.35 U/mg. After increasing the capecitabine dose to 1,800 mg, oxaliplatin and bevacizumab were added. Subsequent DPD protein measurement showed that the level had increased to approximately 12-fold the one before chemotherapy. Sequencing of all 23 exons of DPYD gene revealed a mutation of guanine to thymine in exon 11 (1156 G>T).

CONCLUSION

This is the first report to indicate that DPD activity can be induced. These findings may provide early indications of a new method for chemotherapy for DPD-deficient patients.

Impact of co-administered drugs on drug monitoring of capecitabine in patients with advanced colorectal cancer

BACKGROUND

Drug monitoring is a useful tool for obtaining detailed information about the disposition of a drug in an individual patient during chemotherapy. According to the international guidelines, the analytical assay for quantification of a compound in biological samples must be validated. Among a number of parameters, peak purity is an important requirement.

MATERIALS AND METHODS

We analyzed pharmacokinetics in patients who received chemotherapy with capecitabine and up to 10 various co-medications.

RESULTS

Out of seven investigated co-administered drugs, we found evidence that the proton pump inhibitor pantoprazole causes peak interferences with capecitabine during high-performance liquid chromatography analysis. Therefore quantification of capecitabine in plasma samples can be inaccurate.

CONCLUSION

We recommend an altered time schedule for co-administered drugs or changing the mobile phase used in the assay.

Clinical pharmacokinetics of capecitabine and its metabolites in combination with the monoclonal antibody bevacizumab

AIM

Capecitabine, designed as a pro-drug to the cytotoxic agent 5-fluorouracil, is widely used in the management of colorectal cancer. This study was designed to investigate whether co-administration of the monoclonal antibody bevacizumab (BVZ) shows potential to modulate the plasma disposition of capecitabine (CCB) and its metabolites.

PATIENTS AND METHODS

Nine patients treated with CCB and BVZ for advanced colorectal cancer entered this pharmacokinetic study. In the first cycle CCB was given alone at doses of 1,250 mg/m2 bi-daily for two weeks with one week rest. In the second cycle BVZ co-administration started simultaneously with oral intake of CCB by short infusion of 7.5 mg/kg.

RESULTS

Mean plasma concentration time curves of CCB and its metabolites were insignificantly lower in the BVZ combination regimen compared to CCB monotherapy. After repeated cycles of BVZ no significant pharmacokinetic interaction was observed.

CONCLUSION

From the pharmacokinetic point of view and in agreement with numerous clinical study data, co-administration of BVZ with CCB appears to be safe and efficient.

Rapid and simplified HPLC-UV method with on-line wavelengths switching for determination of capecitabine in human plasma

Capecitabine is an important oral fluoropyrimidine anticancer drug. The purpose of this study was to overcome limitations of previously reported methods and propose an optimized and widely available tool for analysis of capecitabine in human plasma. The simplification of the liquid-liquid extraction procedure involved elimination of unnecessary addition of phosphoric acid and reduction of the extraction solvent volume. The use of voriconazole as the internal standard, combined with gradient elution and on-line wavelength switching, assured very high within- and between-run precision of results (relative standard deviation < 7.1% for lower limit of quantification) and enabled the reduction of the total chromatographic run time to 8 min. The calibration curve was linear within the range of 0.05-10.00 microg/mL and the method selectivity was confirmed in the presence of capecitabine metabolites. All validation parameters met the acceptance criteria set by international regulatory guidances, which proves that the method leads to reliable results. The method may be applied in human pharmacokinetic studies, for the regulatory purposes and therapeutic drug monitoring.

The role of IVS14+1 G > A genotype detection in the dihydropyrimidine dehydrogenase gene and pharmacokinetic monitoring of 5-fluorouracil in the individualized adjustment of 5-fluorouracil for patients with local advanced and metastatic colorectal cancer: a preliminary report

AIM

We retrospectively investigated the relationship between IVS14+1 G > A genotype of the dihydropyrimidine dehydrogenase (DPD) gene with plasma concentration of 5-fluorouracil (5-FU) as well as adverse reactions in 80 patients with locally advanced or metastatic colorectal cancer.

PATIENTS AND METHODS

Eighty patients with un-resectable locally advanced or metastatic colorectal cancer were treated with Folfox-6 regimen, which repeated every two weeks for at least three cycles. Single nucleotide polymorphisms for DPD gene were analyzed before chemotherapy by high-resolution melting (HRM) analysis. The plasma concentration of fluorouracil was measured by high performance liquid chromatography (HPLC) after continuous infusion of fluorouracil over 12 h in each cycle. The average values of plasma concentrations in each cycle were calculated, and the factors related to plasma concentration of 5-FU were screened by stepwise regression.

RESULTS

All patients were divided into three groups according to the predictive confidence interval of plasma concentration of 5-FU, and the average plasma concentrations of fluorouracil in each cycle of these three groups were less than or equal to 26.83 mg/L, 26.83-40.62 mg/L, and more than 40.62 mg/L, respectively. Stepwise regression analysis showed that the plasma concentration of fluorouracil was associated with myelosuppression, hand-foot syndrome, diarrhea, overall survival (OS) and DPD genotype. In efficacy, the median progression-free survival PFS (mPFS) and OS (mOS) of group 2 and group 3 were both significantly higher than those of group 1.

CONCLUSIONS

Among the advanced colorectal cancer patients receiving fluorouracil-based chemotherapy, those with plasma concentration of 5-FU above 26.83 mg/L can obtain better survival; for patients with heterozygous DPD IVS14+1 mutation, 5-FU dose should be appropriately reduced according to last plasma concentration to reduce adverse reactions, while the homozygous ones should avoid application of 5-FU and its derivatives.

Phase 1 study of efatutazone, a novel oral peroxisome proliferator-activated receptor gamma agonist, in combination with FOLFIRI as second-line therapy in patients with metastatic colorectal cancer

Background Efatutazone, a novel oral highly-selective peroxisome proliferator-activated receptor gamma (PPARγ) agonist, has demonstrated some inhibitory effects on disease stabilization in patients with metastatic colorectal cancer (mCRC) enrolled in previous phase I studies. Here, we evaluate the safety and pharmacokinetics of efatutazone combined with FOLFIRI (5-fluorouracil, levo-leucovorin, and irinotecan) as second-line chemotherapy in Japanese patients with mCRC. Methods Dose-limiting toxicities (DLTs) were evaluated at 2 efatutazone dose levels of 0.25 and 0.50 mg (the recommended dose [RD] of efatutazone monotherapy) twice daily in combination with FOLFIRI in a 3–9 patient cohort. Furthermore, tolerability at the RD level was assessed in additional patients, up to 12 in total. Blood samples for pharmacokinetics and biomarkers and tumor samples for archival tissues were collected from all patients. Results Fifteen patients (0.25 mg, 3; 0.5 mg, 12) were enrolled. No DLTs were observed. Most patients experienced weight increase (100 %) and edema (80.0 %), which were manageable with diuretics. Common grade 3/4 toxicities were neutropenia (93.3 %), leukopenia (46.7 %), and anemia (33.3 %). Stable disease was observed in 8 of the 14 patients evaluable for tumor response. The plasma adiponectin levels increased over time and increased dose. No clear relationship was detected between treatment efficacies and plasma levels of adiponectin as well as the expression levels of PPARγ and the retinoid X receptor in tumor tissues. Conclusions Efatutazone combined with FOLFIRI demonstrates an acceptable safety profile and evidence of disease stabilization in Japanese patients with mCRC. The RD for efatutazone monotherapy can be used in combination with FOLFIRI.

[Neoadjuvant chemotherapy and radiation therapy of resectable cancer recti of distal localization]

The method of combined neoadjuvant treatment of resectable cancer recti, consisting of preoperative radiaton therapy, using big-fractionized intensive irradiation on the endolymphatic chemotherapy background together with fluorouracil with following surgical intervention (main group), in terms up to 72 h, was elaborated in the clinic. The patients, to whom the chemotherapy and radiation therapy were conducted, were included into control groups. Postoperative complications have had occurred in 8 (12.5%) patients of the main group and in 10 (15.87%) and 13 (14.29%)--in control groups. The five-year survival indices in the main group have constituted (73.5 +/- 6.3)%, and in control groups--(64.6 +/- 5.8) and (64.4 +/- 6.8)%. The local recurrence rate in the main group have constituted (6.2 +/- 3.0)%, and of the remote metastatizing--(15.6 +/- 4.5)%.

Evaluation of 5-FU plasma concentration by 13C breath test in patients treated with oral 5-FU analogs

BACKGROUND/AIM

The objective of this study was to investigate the influence of digestive gastrointestinal absorption function on the pharmacokinetics of the orally-administered anticancer drug, Tegafur-gimestat-otastat potassium (TS-1), by measuring the plasma 5-fluorouracil (5-FU) concentration using stable isotope breath tests.

PATIENTS AND METHODS

Twenty-nine patients with progressive/recurrent digestive organ cancer were enrolled for this pharmacokinetic study, and blood samples were obtained from each patient. The area under-the-time-concentration curve between 0 and 480 min (AUC0-480 min), time-of-drug concentration peak (T(max)), maximum drug concentration (C(max)) and the half-life period (t(1/2)) of 5-FU were investigated. Simultaneously, a continuous (13)C-acetate breath test was performed for each patient. The parameters measured with the breath test were the area under the (13)CO(2) excretion rate curve between 0-4 h (AUC(0-4h)), peak (13)CO(2) value and elimination rate constant (K(el)) value.

RESULTS

The AUC(0-8h) and C(max) of 5-FU were significantly correlated with K(el) (p=0.012 and p=0.024, respectively), and the 5-FU C(max) value was significantly correlated with the peak value of (13)CO(2) (p=0.037). Multivariate regression analysis also found the C(max) of 5-FU to be associated with K(el) (p=0.0118). The C(max) and AUC(0-8h) of 5-FU were also significantly correlated (p<0.0001).

CONCLUSION

The results of this study suggest that gastrointestinal absorption is closely-related to plasma 5-FU concentration after oral administration of TS-1.

An immunoassay method for the pharmacokinetics of 5-fluorouracil in patients with gastric cancer administered adjuvant chemotherapy

Conventional gas chromatography-mass spectrometry (GC-MS) was compared with a new immunoassay method for measuring plasma (5-FU) concentrations in adjuvant chemotherapy with TS-1 for patients with gastric cancer. TS-1 was administered orally to patients after gastrectomy. Blood samples for pharmacokinetic analysis were collected on the seventh day of treatment. The mean area under the time concentration curve (AUC)(0-8), half-life (t(1/2)), and maximum drug concentration (C(max)) obtained by the two methods were as follows: GC-MS, 847.9 μg/ml/hr, 2.76 h, and 186.6 ng/ml; and immunoassay, 1311.2 μg/ml/hr, 3.5 h, and 259.8 ng/ml. Significant correlations were observed for AUC(0-8) (p=0.0001), C(max) (p=0.0007), and changes in the 5-FU concentration in blood over time (p=0.018) for the two methods. Compared with the conventional GC-MS method, the new immunoassay method provides similar results, but is simpler and results can be obtained earlier. This method will be useful for monitoring the 5-FU concentration in serum from patients with gastric cancer receiving TS-1.

[Pharmacokinetics of S-1 capsule in patients with advanced gastric cancer]

The study is to investigate the pharmacokinetics of S-1 capsule (tegafur, gimeracil and potassium oxonate capsule) in patients with advanced gastric cancer after single and multiple oral administration. Twelve patients with advanced gastric cancer were recruited to the study. The dose of S-1 for each patient was determined according to his/her body surface area (BSA). The dose for single administration was 60 mg every subject. The dose for multiple administration for one subject was as follows: 100 mg x d(-1) or 120 mg x d(-1), 28-days consecutive oral administration. The pharmacokinetic parameters of tegafur, 5-fluorouracil, gimeracil, potassium oxonate and uracil after single oral administration were as follows: (2,207 +/- 545), (220.0 +/- 68.2), (374.9 +/- 103.0), (110.5 +/- 100.8) and (831.1 +/- 199.9) ng x mL(-1) for Cmax; (11.8 +/- 3.8), (4.4 +/- 3.3), (7.8 +/- 5.1), (3.1 +/- 0.9) and (8.8 +/- 4.1) h for t1/2, respectively. After six days oral administration, the average steady state plasma concentrations (Cav) of tegafur, 5-fluorouracil, gimeracil, potassium oxonate and uracil were (2,425 +/- 1,172), (73.88 +/- 18.88), (162.6 +/- 70.8), (36.89 +/- 29.35) and (435.3 +/- 141.0) ng x mL(-1), respectively, and the degree of fluctuation (DF) were (1.0 +/- 0.2), (2.5 +/- 0.4), (3.1 +/- 0.8), (2.4 +/- 0.8) and (1.5 +/- 0.3), respectively. The cumulative urine excretion percentage of tegafur, 5-fluorouracil, gimeracil and potassium oxonate in urine within 48 h were (4.2 +/- 2.8) %, (4.7 +/- 1.6) %, (18.5 +/- 6.0) % and (1.7 +/- 1.2) %, repectively, after single oral administration of S-1. The results exhibited that tegafur had some drug accumulation observed, and gimeracil, potassium oxonate, 5-fluorouracil and uracil had no drug accumulation observed.

Pharmacokinetics of 5-fluorouracil and cyclophosphamide in depression rats

OBJECTIVES

Efficacy and toxicity of the drug are mainly determined by physicochemical properties and pharmacological effects of its own. In addition, they are also affected by other factors, such as gender, age, genetic character, pathophysiological status, mood states and so on. The paper aims to study whether mood disorder alters drug metabolism process through the pharmacokinetic research on some clinically important anticancer drugs in depression model rats.

MATERIALS AND METHODS

The depression model rats were built by exposing to chronic unpredicted mild stresses (CUMS) for 8 weeks. 36 female Sprague-Dawley (SD) rats were randomized into model group and control group. In each group, 18 rats were randomized into 2 subgroups: 5-fluorouracil (5-FU) subgroup and cyclophosphamide (CP) subgroup which were given a certain doses of 5-FU and CP. The blood samples were collected at different time points and plasma drug concentration were respectively assayed by high performance liquid chromatography (HPLC) for 5-FU and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for CP. Pharmacokinetic parameters were processed with DAS software.

RESULTS

There were significant differences in the pharmacokinetic parameters of 5-FU and CP between in depression model rats group and in the normal control group (p < 0.05), except t1/2alpha (p > 0.05) for CP pharmacokinetics in depression model rats group and in the normal control rats group, with the value of those was 0.07 and 0.09 h.

CONCLUSIONS

Depression mood disorder might alter drug metabolism process.

[Role of pharmacokinetic monitoring of serum fluorouracil concentration in patients with local advanced and metastatic colorectal cancer and further improving efficacy of fluorouracil-based chemotherapy]

OBJECTIVE

To investigate the relationship between serum concentration of fluorouracil and therapeutic efficacy as well as adverse reactions in patients with unresectable locally advanced or measurable metastatic colorectal cancer, and to analyze its role in further improving therapeutic efficacy and reducing adverse reactions of fluorouracil-based chemotherapy.

METHODS

Eighty-six patients were randomly assigned into three groups according to the average plasma concentration of fluorouracil after three cycles of chemotherapy with the initial regimen of two weeks FOLFOX-4 (oxaliplatin + leucovorin + fluorouracil) or FOLFIRI (irinotecan + leucovorin + fluorouracil): group 1 (plasma concentration of fluorouracil < 25 ng/ml), group 2 (25 - 35 ng/ml) and group 3 (> 35 ng/ml). The blood samples were taken at 12 h after continuous infusion of fluorouracil in each cycle and the plasma concentration of fluorouracil was detected by high performance liquid chromatography (HPLC) (about 5 am ± 1 h). The relationship between the drug plasma concentration, therapeutic efficacy and adverse reactions in different fluorouracil plasma concentration arms was analyzed retrospectively.

RESULTS

The average plasma concentrations of fluorouracil of the three groups were (23.48 ± 1.95) ng/ml, (31.47 ± 2.33) ng/ml and (39.89 ± 3.87) ng/ml, respectively (P < 0.01). As for therapeutic efficacy, the median OS of the groups 2 and 3 were 18.0 and 17.5 months, significantly higher than that in the group 1 (13.0 months, P < 0.01). The PFS were 4.5, 7.5 and 8.0 months, respectively (P < 0.01). In terms of adverse reactions, the incidences of bone marrow suppression, mucositis and diarrhea in the group 3 were significantly higher than that in the first two groups (P = 0.02, P = 0.04 and P = 0.02).

CONCLUSIONS

The patients with local advanced and metastatic colorectal cancer, receiving fluorouracil-based chemotherapy, and with an average plasma concentration of fluorouracil between 25 - 35 mg/L have a better prognosis, and lower incidence of adverse reactions such as bone marrow suppression, mucositis and diarrhea.

Matrix metalloproteinase-8 mediates the unfavorable systemic impact of local irradiation on pharmacokinetics of anti-cancer drug 5-Fluorouracil

Concurrent chemoradiation with 5-fluorouracil (5-FU) is widely accepted for cancer treatment. However, the interactions between radiation and 5-FU remain unclear. Here, we evaluated the influence of local irradiation on the pharmacokinetics of 5-FU in rats. The single-fraction radiation was delivered to the whole pelvic fields of Sprague-Dawley rats after computerized tomography-based planning. 5-FU at 100 mg/kg was prescribed 24 hours after radiation. A high-performance liquid chromatography system was used to measure 5-FU in the blood. Matrix metalloproteinase-8 (MMP-8) inhibitor I was administered to examine whether or not RT modulation of 5-FU pharmacokinetic parameters could be blocked. Compared with sham-irradiated controls, whole pelvic irradiation reduced the area under the concentration versus time curve (AUC) of 5-FU in plasma and, in contrast, increased in bile with a radiation dose-dependent manner. Based on protein array analysis, the amount of plasma MMP-8 was increased by whole pelvic irradiation (2.8-fold by 0.5 Gy and 5.3-fold by 2 Gy) in comparison with controls. Pretreatment with MMP-8 inhibitor reversed the effect of irradiation on AUC of 5-FU in plasma. Our findings first indicate that local irradiation modulate the systemic pharmacokinetics of 5-FU through stimulating the release of MMP-8. The pharmacokinetics of 5-FU during concurrent chemoradiaiton therapy should be rechecked and the optimal 5-FU dose should be reevaluated, and adjusted if necessary, during CCRT.

[A case of toxicity caused by drug interaction between capecitabine and phenytoin in patient with colorectal cancer]

We present a case of toxicity caused by a drug interaction between capecitabine and phenytoin (PHT). The drug combination elevated the plasma level of PHT in a patient on chemotherapy with capecitabine for colorectal cancer. Our patient was a 44-year-old woman diagnosed with epilepsy in her 20's, being treated with valproic acid (VPA) and PHT. Adjuvant chemotherapy with capecitabine began following surgery for colorectal cancer. Seven weeks later, she developed numbness, dizziness, dysarthria and difficulty walking, and was hospitalized for investigation. Her serum PHT level was elevated at 35. 1 μg/ mL. This case suggests that when capecitabine and PHT are coadministered, PHT levels should be monitored frequently, and that PHT dosage should be adjusted accordingly if it cannot be replaced by an alternative anticonvulsant.

A rapid and simple HPLC assay for quantification of capecitabine for drug monitoring purposes

AIM

Capecitabine, a 5-fluorouracil prodrug, has been integrated into the management of multiple cancer types. In order to obtain information about plasma levels of capecitabine in patients who had drug intake at home during chemotherapy, a simple HPLC method for capecitabine monitoring has been developed and validated.

PATIENTS AND METHODS

Capecitabine levels were quantified by a simple reversed-phase HPLC system with an external standard method. Plasma samples were obtained from 12 colorectal cancer patients who underwent chemotherapy with capecitabine alone (1000 mg/m(2)) or combined with oxaliplatin (130 mg/m(2)).

RESULTS

Although there was evidence that capecitabine had not been taken according to the chemotherapeutic schedule in two cases, the study demonstrated that its combination with oxaliplatin showed no significant drug-drug interactions.

CONCLUSION

Due to its robustness, specificity and sensitivity, the method is also well-suited for capecitabine analysis in other pharmacokinetic studies.

[Effect of pylorus-preserving pancreaticoduodenectomy on serum levels of 5-fluorouracil during S-1 treatment for pancreaticobiliary malignancy]

AIMS

The aim of this study was to evaluate the effect of surgical procedures on the serum levels of 5-fluorouracil (5-FU) in patients undergoing S-1 treatment for pancreaticobiliary malignancy.

METHODOLOGY

From January 2003 through December 2008, 27 chemotherapy-naive patients who underwent a surgical procedure for pancreaticobiliary malignancy received S-1 chemotherapy for unresectable or recurrent disease. The primary site of disease was: the extra hepatic bile duct (n=10); gallbladder (n=8); pancreas (n=6); or ampulla of Vater (n=3). The surgical procedure was: pylorus-preserving pancreaticoduodenectomy (PPPD) (n=6); combined major hepatic and bile duct resection (n=6); bilioenteric anastomosis (n=4); or exploratory laparotomy (n=11). S-1 (80-120 mg/day) was administered orally twice daily for 28 days, followed by 14 days without therapy. Subsequently, the serum levels of 5-FU were measured using the HPLC-UV method.

RESULTS

The median number of cycles administered per patient was 6 (range, 2-13). Although grade 3 watery eye developed in one patient, neither grade 4 toxicities nor treatment-related deaths were observed. The overall response rate was 19%, the median overall survival time was 9 months, and the 1-year cumulative survival rate was 11%. The maximum levels of 5-FU in the sera of individual patients differed significantly according to the surgical procedure (Kruskal-Wallis test; p=0. 0049); the patients who underwent PPPD had the highest 5-FU levels, as compared with the other patients (Mann-Whitney test; p= 0.003).

CONCLUSIONS

The type of operative procedure appears to influence the serum levels of 5-FU in S-1-treated surgical patients with pancreaticobiliary malignancy. Given the possibility of elevated levels of 5-FU in the sera of patients who are treated with S-1 after PPPD, adverse events must be monitored carefully in this cohort.

An APCI LC-MS/MS method for routine determination of capecitabine and its metabolites in human plasma

The anticancer drug capecitabine and its metabolites [including the active metabolite 5-fluorouracil (5-FU)] display high pharmacokinetic inter-patient variability. Such variability, which may lead to treatment failure or toxicity, could need drug concentration measurement to individualize dosing regimen. However, usual assay methods are often long and fastidious. A simultaneous and cost-effective method was thus developed for the determination of the concentrations of these compounds in human plasma. Compounds were extracted via a classic liquid-liquid extraction. Chromatographic analysis was performed on a C18 reverse phase column with detection by atmosphere pressure chemical ionization LC-MS/MS. Our method allows a good chromatographic separation of the compounds and was fully validated following Food and Drug Administration (FDA) recommendations (good selectivity, no carry-over, linearity of the calibration curves without weighting, deviations from nominal concentrations of standard samples lower than 15%, intra- and inter-assay precision and accuracy lower than 15%). Recovery and stability were also acceptable following the FDA guidelines. A matrix effect impairing the determination of 5-FU was avoided by using a stable isotopic derivative of 5-FU as internal standard. Interestingly, this method allows detection of TetraHydroUridine, an inhibitor of ex vivo degradation of metabolites, which is essential for the stability, the adequate conditioning of blood samples and for good laboratory practice, essential in routine determination. This method seems usable to routinely determine concentrations of capecitabine and its metabolites in blood and may be helpful in further studies aiming at performing therapeutic drug monitoring.

Clinical and pharmacokinetics study of oxaliplatin in colon cancer patients

AIM

to evaluate the therapeutic efficacy of oxaliplatin and to analyze the pharmacokinetics of both ultrafiltrable (free) and protein-bound platinum in patients with metastatic colon cancer.

METHOD

60 patients with stage IV colon carcinoma received 4-6 (mean 4.5) cycles of oxaliplatin based combination chemotherapy. Response rate, progression-free survival (PFS) and toxicity were evaluated. The pharmacokinetics of oxaliplatin was evaluated in 8 patients who were given 85 mg/sqm or 130 mg/sqm using an infusion time of 2-4 h. Pharmacokinetic analysis was performed on blood, plasma and plasma ultrafiltrable by ICP-MS (Inductively Coupled Plasma Mass Spectrometry).

RESULTS

Overall response rate (complete and partial) occurred in 33 (55%) patients. The median time of progression was 9.3 months. Cumulative neurotoxicity, vomiting and diarrhea, myelosuppression appeared in 32.3%, 21.3%, and 39.4% patients, respectively. The mean Cmax and AUC 0-24 of oxaliplatin increased in a dose-related manner. The pharmacokinetics of platinum after oxaliplatin administration was triphasic characterized by a short initial distribution phase and a long terminal elimination phase.The clearance of ultrafiltrable platinum was relatively high and the clearance of platinum from plasma and blood cells was relatively low, which is probably a reflection of the covalent binding of platinum to these matrices.

CONCLUSION

Oxaliplatin is active and well tolerated in patients with advanced colon cancer. With a relatively low interpatient variability, it is eliminated triphasically and the mean Cmax and AUC 0-24 increases in a dose-related manner. These results provide a scientific basis for the safe and effective use of oxaliplatin in the clinic.

[Pharmacokinetic monitoring of 5-fluorouracil may improve the clinical benefit with an individualized regimen-a case report]

Serum levels of 5-fluorouracil(5-FU)were measured in a patient receiving pharmacokinetic modulation chemotherapy( PMC), with 5-FU, as well as a combination of oxaliplatin and infusional 5-FU plus leucovorin(FOLFOX). A 77- year-old man presented with unresectable multiple hepatic metastases after abdominoperineal resection of rectal / carcinoma, and was successfully treated by PMC. The patient initially received infusional 5-FU at 750 mg/m(2) once a week, and showed a partial response. Serum 5-FU levels were higher at night, and the peak concentration of 5-FU was / 398 ng/mL. After 13 months of PMC, second-line chemotherapy with FOLFOX was initiated because new liver metastases had appeared. After 4 cycles of FOLFOX4, progression was observed, and the concentration profile of 5-FU / was measured. The area under the concentration vs. time curve(AUC ngxh/mL)was smaller with FOLFOX4 than with PMC, so the FOLFOX6 regimen was tried instead. The AUC increased and disease progression was suppressed. This case shows that individual adjustment of the dose and regimen based on pharmacokinetic monitoring can increase the clinical benefit of fluorouracil.

[Distribution of 5-FU in rat plasma and liver tissue after local 5-FU infusion]

OBJECTIVE

To study the distribution of 5-FU in rat plasma and liver tissue following systemic or local 5-FU infusion.

METHODS

5-FU was administered at the dose of 20 mg/kg systemically via bolus injection through the jugular vein or locally via infusion through the hepatic artery and portal vein of the rats. High-performance liquid chromatography was used to measure 5-FU concentration in the plasma and liver tissue, and the pharmacokinetic parameters, penetration rate and therapeutic dominance of 5-FU were calculated.

RESULTS

Systemic administration of 5-FU resulted in the peak 5-FU concentration (Cmax) and area under curve (AUC) in the liver tissue of 13.79-/+4.56 microg/g and 342.20-/+108.20 microg.min(-1).g(-1)g-1, with the plasma Cmax and AUC of 36.85-/+5.96 microg/g and 842.00-/+158.00 microg.min(-1).ml(-1), respectively. Local 5-FU administration through the hepatic artery resulted in Cmax and AUC in the liver tissue of 29.58-/+4.30 microg/g and 794.60-/+115.40 microg.min(-1).g(-1) and Cmax and AUC in the plasma of 24.39-/+4.63 microg/g and 639.70-/+133.80 microg.min(-1).ml(-1), respectively. After administration through the portal vein, the Cmax and AUC of 5-FU was 28.21-/+4.46 microg/g and 733.60-/+180.3 microg.min(-1).g(-1) in the liver tissue, and 21.02-/+4.06 microg/ml and 529.80-/+111.50 microg.min(-1).ml(-1) in the plasma, respectively.

CONCLUSION

Compared with systemic venous bolus injection, administration through the hepatic artery and portal vein can significantly increase 5-FU concentration in the liver, and decrease its concentration in the peripheral blood.

In-vivo evaluation in rats of colon-specific microspheres containing 5-fluorouracil

The aims of this investigation were to determine the distribution in the gastrointestinal (GI) tract of Eudragit S-100 encapsulated colon-specific sodium alginate microspheres containing 5-fluorouracil (5-FU) in rats, and to perform pharmacokinetic and pharmacodynamic studies. Comparisons were with a control immediate-release (IR) formulation of 5-FU. 5-FU was distributed predominantly in the upper GI tract from the IR formulation but was distributed primarily to the lower part of the GI tract from the microsphere formulation. No drug was released in the stomach and intestinal regions from the colon-specific microspheres. Significantly, a high concentration of the active drug was achieved in colonic tissues from the colon-specific microspheres (P < 0.001), which was higher than the IC50 required to halt the growth of and/or kill colon cancer cells. Colon cancer was induced in rats by subcutaneous injection of 1,2-dimethylhydrazine (40 mg kg (-1)) for 10 weeks. The tumours induced were non-invasive adenocarcinomas and were in Duke's stage A. The 5-FU formulations were administered for 4 weeks after tumour induction. Non-significant reductions in tumour volume and multiplicity were observed in animals given the colon-specific microspheres. Enhanced levels of liver enzymes (SGOT, SGPT and alkaline phosphatase) were found in animals given the IR formulation of 5-FU, and values differed significantly (P < 0.001) from those in animals treated with the colon-specific microspheres. Elevated levels of serum albumin and creatinine, and leucocytopenia and thrombocytopenia were observed in the animals given the IR formulation. In summary, Eudragit S-100 coated alginate microspheres delivered 5-FU to colonic tissues, with reduced systemic side-effects. A long-term dosing study is required to ascertain the therapeutic benefits.

[Results of hepatic arterial infusion chemotherapy with 5-FU and leucovorin for unresectable liver metastases from colorectal cancer]

PURPOSE

Hepaticarterial infusional(HAI)5-FU chemotherapy, which involves the use of interventional radiology technique, has matured technically in Japan in the 1990's. The antitumor effect of 5-FU is enhanced by combination with leucovorin. This study was performed to evaluate the efficacy and toxicity of HAI 5-FU and leucovorin chemotherapy for patients with unresectable liver metastases from colorectal cancer.

METHODS

Treatment was given to 20 patients with unresectable liver metastases from colorectal cancer. The chemotherapy regimen consisted of weekly HAI of 5-FU(1,000 mg/body)and leucovorin(250 mg/body)over five hours. The survival and response rates to the therapy were assessed according to RECIST. Hematologic and non-hematologic toxicity was assessed according to CTCAE v3.0.

RESULTS

Combined HAI 5-FU and leucovorin therapy was carried out an average of 27 times. The response rate for liver tumors was 75%, and the median survival time was 22 months. The applied regimen caused only mild adverse events. There was no evidence of myelosuppression except for platelet decrease(grade 3)in a patient with chronic renal failure.

CONCLUSION

This HAI approach using 5-FU and leucovorin was effective and the therapy for unresectable liver metastases from colorectal cancer was tolerated well. Therefore the HAI approach should be reconsidered as an effective therapy against this disease in Japan.

Quantitation of 5-fluorouracil (5-FU) in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry

5-Fluorouracil (5-FU) has long had a place in the treatment of many malignancies. 5-FU plasma concentrations have been correlated with toxicity and efficacy, and therapeutic drug monitoring has been reported to result in an improved response/toxicity balance. We report validation, according to FDA guidelines, of a hydrophilic interaction chromatography (HILIC) liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay for the sensitive, accurate and precise quantitation of 5-FU in human plasma. The assay employed an isotopically labeled 5-FU internal standard and ethyl acetate extraction. Separation was achieved with an amino column and an isocratic mobile phase of 0.1% formic acid in acetonitrile/water (97:3, v/v), followed by a wash. Detection consisted of electrospray, negative-mode ionization tandem mass spectrometry in the multiple reaction monitoring (MRM) mode. The accuracy was 96.0-102.2%, and precision was 2.1-7.5% in the concentration range of 10-10 000 ng/mL. Recovery from plasma was 46.0-72.6%, and ion suppression was 9.8-25.7%. Plasma freeze/thaw stability was 87.5-104.3%, and stability for 4 h at room temperature was 98.7-100.0%. This assay is currently being used to quantitate 5-FU in human plasma samples.

Concentrations of the DNA methyltransferase inhibitor 5-fluoro-2'-deoxycytidine (FdCyd) and its cytotoxic metabolites in plasma of patients treated with FdCyd and tetrahydrouridine (THU)

PURPOSE

Although the DNA methyltransferase inhibitor 5-fluoro-2'-deoxycytidine (FdCyd), is being evaluated clinically, it must be combined with the cytidine deaminase inhibitor tetrahydrouridine (THU) to prevent rapid metabolism of FdCyd to the pharmacologically active, yet unwanted, metabolites 5-fluoro-2'-deoxyuridine (FdUrd), 5-fluorouracil (FU), and 5-fluorouridine (FUrd). We assessed plasma concentrations of FdCyd and metabolites in patients receiving FdCyd and THU.

METHODS

We validated an LC-MS/MS assay, developed for a preclinical study, to quantitate FdCyd and metabolites in human plasma. Patients were treated with five daily, 3-h infusions of FdCyd at doses of 5-80 mg/m(2) with 350 mg/m(2) THU. Plasma was obtained during, and before the end of infusions on days 1 and 5.

RESULTS

The lower limits of quantitation for FU, FdUrd, FUrd, FC and FdCyd were 1, 1.5, 10, 3, and 10 ng/ml, respectively. Plasma FdCyd increased with dose, from 19-96 ng/ml at 5 mg/m(2) to 1,600-1,728 ng/ml at 80 mg/m(2). FdUrd was undetectable in patients treated with FdCyd doses <20 mg/m(2), and increased from 2.3 ng/ml at 20 mg/m(2) to 3.5-5.7 ng/ml at 80 mg/m(2). FU increased from 1.2-5.5 ng/ml at 5 mg/m(2) to 6.0-12 ng/ml at 80 mg/m(2).

CONCLUSIONS

By co-administering FdCyd with THU, FdCyd plasma concentrations were achieved that are known to inhibit DNA methylation in vitro. The accompanying plasma FU and FdUrd concentrations are <10% those observed after therapeutic infusions of FU or FdUrd, while FdCyd levels are well above those required to inhibit methylation in vitro. Therefore, inhibition of DNA methylation with FdCyd and THU appears feasible.

[Biodistribution of (99m)Tc-labeled anti-VEGF mAb 5-FU loaded polylactic acid nanoparticles in human gastric carcinoma xenografts]

OBJECTIVE

To prepare (99m)Tc-labeled Anti-VEGF mAb 5-FU loaded polylactic acid nanoparticles ((99m)Tc-Ab-5-FU-NPs) and investigate its biodistribution in human gastric carcinoma xenografts.

METHODS

(99m)Tc-Ab-5-FU-NPs were prepared by labeling Ab-5-FU-NPs with (99m)Tc using improved Schwarz method. After isolation of (99m)Tc-Ab-5-FU-NPs using SephadexG250 column, the labeling ratio and radiochemical purity were determined using chromatography. The immunocompetence of (99m)Tc- Ab-5-FU-NPs was detected by ELISA and immunohistochemistry. (99m)Tc-Ab-5-FU-NPs were then injected via the tail vein into SCID mice bearing human gastric carcinoma, and (99m)Tc labeled mice-derived monoclonal IgG loaded polylactic acid nanoparticles were used as the control, followed by radioimmunoscintigraphic imaging at 2 and 6 h. The radioactive count and radioactive ratio of the tumor and non-tumor tissue (T/NT) in the animal models were calculated using ROI technique. After imaging at 24 h, SCID mice were sacrificed and the radioactive distribution, the %ID/g, as well as the T/NT radioactive ratio were examined, respectively. The concentrations of 5-FU in the tumor and blood were also detected using HPLC method.

RESULTS

The labeling ratio of (99m)Tc-Ab-5-FU-NPs was 90%-95%. (99m)Tc-Ab-5-FU-NPs were detected in the tumor tissues by radioimmunoimaging 2 h after the injection. ID%/g in the tumor tissues at 2 and 6 h were both significantly higher than that of the control group. Both the ID%/g in tumor tissues and radioactive ratio of tumor and blood at 6 h were higher than those at 2 h, and the concentration of 5-FU in experimental group increased continuously with time and was significantly higher than that in control group.

CONCLUSIONS

(99m)Tc-Ab-5-FU-NPs prepared in this study can meet the demands of radioimmunoimaging, and the anti-VEGF monoclonal antibody possesses reliable immune targeting ability. Six hours after injection, (99m)Tc-Ab-5-FU-NPs can specifically accumulate in the tumor tissues in human gastric carcinoma xenografts at high concentration.

5-Fluorouracil plasma levels and biodegradation of subcutaneously injected drug-loaded microspheres prepared by spray-drying poly(d,l-lactide) and poly(d,l-lactide-co-glycolide) polymers

Microspheres (MS) of 5-fluorouracil-loaded poly(D,L-lactide) (PLA), poly(D,L-lactide-co-glycolide) 75/25 (PLGA 75/25) and poly(D,L-lactide-co-glycolide) 50/50 (PLGA 50/50) prepared by the spray-drying technique were subcutaneously injected in the back of Wistar rats in order to evaluate the 5-fluorouracil (5-FU) release and the biodegradation characteristics. Determination of plasma 5-FU concentration by HPLC with analysis of data using a non-compartmental model showed drug in plasma between 9 and 14 days after administration of drug-loaded PLGA 50/50 or PLA and PLGA 75/25 microspheres, respectively, with a maximum drug concentration of 2.4+/-0.2microg/mL at 24h (5-FU-loaded PLGA 50/50 MS), 2.5+/-0.1microg/mL at 48h (5-FU-loaded PLGA 75/25 MS), and 2.3+/-0.1microg/mL at 24h (5-FU-loaded PLA MS). Pharmacokinetically, a significant increase of AUC (up to 50 times) and MRT (up to 196 times) of 5-FU with regard to the administration of the drug in solution was observed. Scanning electron microscopy and histological studies indicated that a small fibrous capsule was observed around the microspheres in the site of injection. One month after the injection of PLGA 50/50 MS and 2 months after the injection of PLGA 75/25 and PLA MS, masses of polymers, instead of single microspheres, were observed. Close to them, macrophagic cells were present, and blood vessels were observed in the connective tissue. Total absence of fibrous capsule and injected microspheres was observed after 2 (for PLGA 50/50 MS) or 3 (PLGA 75/25 and PLA MS) months.

DPYD*5 gene mutation contributes to the reduced DPYD enzyme activity and chemotherapeutic toxicity of 5-FU

BACKGROUND

Dihydropyrimidine dehydrogenase (DPYD) plays an important role in the metabolism of 5-FU, which can directly influence the pharmacokinetics and toxicity of 5-FU in patients undergoing chemotherapy. However, little is known of the relationship between DPYD gene polymorphism and metabolism and chemotherapeutic toxicity of 5-FU in gastric carcinoma and colon carcinoma. The present genotyping study demonstrated the relationship between DPYD gene polymorphism among 75 gastric carcinoma and colon carcinoma patients and its impact on 5-FU pharmacokinetic and side effect.

METHODS

We used a chemotherapy scheme based on 5-FU for the treatment of 75 patients with gastrointestinal carcinoma and detected the serum drug concentration and DPYD gene polymorphism (DPYD*2, *3, *4 *5 *9 *12).

RESULTS

We found that there were no DPYD*2, *3, *4, *12 type mutation, in all patients. Of DPYD*9 gene polymorphism loci in 75 patients, 7 were heterozygote and 68 wild type; of DPYD*5 gene polymorphism loci in 75 patients, 11 were mutation and 23 heterozygote and 41 wild type. The elimination rate constant (Ke) value of DPYD*5 mutation group was statistically lower than the wild type (p=0.022). The incidence of middle-severe nausea and vomiting and white blood cell decreases in DPYD*5 gene type ranging from the highest to lowest can be listed as: mutation, heterozygote, wild type (p<0.05). The incidence of middle-severe nausea and vomiting was significantly higher in DPYD*9 heterozygous genotype than in DPYD*9 wild genotype (p<0.05).

CONCLUSIONS

DPYD*5 gene mutation contribute to reduced DPYD enzyme activity and 5-FU dysmetabolism, which is associated with the accumulation of 5-FU and the chemotherapeutic toxicity in gastric carcinoma and colon carcinoma.

A rapid and inexpensive method for anticipating severe toxicity to fluorouracil and fluorouracil-based chemotherapy

Dihydropyrimidine dehydrogenase (DPD) deficiency leads to dramatic overexposure to fluorouracil (5-FU), resulting in a potentially lethal outcome in patients treated with standard doses. The aim of this study was to validate, in a routine clinical setting, a simple and rapid method to determine the DPD status in a subset of cancer patients, all presenting with life-threatening toxicities following 5-FU or capecitabine intake. In this study, 80 out of 615 patients (13%) suffered severe toxicities, including 5 lethal ones (0.8%), during or after chemotherapy with a fluoropyrimidine drug. Patients with severe toxicities were treated with 5-FU (76 patients) or capecitabine-containing protocols (4 patients). Simplified uracil to di-hydrouracil (U/UH2) ratio determination in plasma was retrospectively performed in these 80 patients, as a surrogate marker of DPD activity. When possible, 5-FU Css determination was performed, and screenings for the canonical IVS14+1G>A mutation were systematically carried out. Comparison of the U/UH2 ratios with a reference, non-toxic population, showed abnormal values suggesting impaired DPD activity in 57 out of the 80 toxic patients (71%) included in this study, and in 4 out of 5 patients (80%) with a fatal outcome. Similarly, drug exposures up to 15 times higher than the range observed in the non-toxic population were also observed. Importantly, no IVS14+1G>A mutation was found in these patients, including those displaying the most severe or lethal toxicities. These data warrant systematic detection of DPD-deficient patients prior to fluoropyrimidine administration, including when oral capecitabine (Xeloda) is scheduled. Finally, the simplified methodology presented here proved to be a low cost and rapid way to identify routinely patients at risk of toxicity with 5-FU or capecitabine.

Identification of a novel mutation in the dihydropyrimidine dehydrogenase gene in a patient with a lethal outcome following 5-fluorouracil administration and the determination of its frequency in a population of 500 patients with colorectal carcinoma

OBJECTIVES

Life-threatening toxic side-effects following 5-FU exposure have been related to deficiency of dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme in its catabolism. We presently report a new DPYD gene SNP in a Spanish woman who died from multivisceral 5-FU-induced toxicity.

DESIGN AND METHODS

We looked for 22 known SNPs by Pyrosequecing. Then, we sequenced the whole 23 exons of DPYD, along with adjacent intronic sequences. PCR was carried out to determine whether or not exons were deleted in the DPYD. To determine whether the predicted stop codon indeed resulted in a truncated protein, a bacterial expression vector was employed to generate the predicted protein. 500 patients were genotyped to determine allele frequency.

RESULTS

A novel mutation 464 T>A was identified in DPYD gene exon 5, resulting in the replacement of leucine 155 by a stop codon in the protein. We confirmed this mutation by Pyrosequencing and its involvement by a protein truncation test. We genotyped the patient's family and the allele frequency was 0.2%.

CONCLUSION

The involvement of this variant in 5-FU life-threatening toxicity supports its inclusion in pretherapeutic genetic screening.

Rapid and simultaneous determination of capecitabine and its metabolites in mouse plasma, mouse serum, and in rabbit bile by high-performance liquid chromatography

A rapid high-performance liquid chromatography method has been developed for simultaneous determination of capecitabine and its metabolites: 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouridine (5'-DFUR) and 5-fluorouracil (5-FU). 5'-DFCR was synthesized by hydrolyzing capecitabine using commercially available carboxyl esterase (CES) and characterized by NMR, mass spectrometry and elemental analysis. Base-line separations between capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were found with symmetrical peak shapes on a Discovery RP-amide C16 column using 10 mM ammonium acetate at pH 4.0 and methanol as the mobile phase. The retention times of capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were 8.9, 5.0, 5.3 and 3.0 min, respectively. Linear calibration curves were obtained for each compound across a range from 1 to 500 microg ml(-1). The intra- and inter-day relative standard deviations (%RSD) were <5%. A single-step protein precipitation method was employed for separation of the analytes from bio-matrices. Greater than 85% recoveries were obtained for capecitabine, 5'-DFCR, 5'-DFUR and 5-FU from bio-fluids including mouse plasma, mouse serum and rabbit bile.

Development of a Pharmacokinetic Model to Optimize the Dosage Regimen of TS-1, a Combination Preparation of Tegafur, Gimeracil and Oteracil Potassium

BACKGROUND

TS-1 is a combination preparation of tegafur, a prodrug of 5-fluorouracil (5-FU), with gimeracil, a potent inhibitor of dihydropyrimidine dehydrogenase (DPD), which mediates the inactivation of 5-FU. UFT is a combination preparation of tegafur with uracil, which also inhibits DPD, though less potently; UFT has a higher content of tegafur than that in TS-1. We aimed to develop a pharmacokinetic model to describe the kinetics of tegafur and 5-FU after the administration of TS-1 and UFT.

METHODS

We developed a model incorporating the inhibition of DPD by gimeracil and uracil, and fitted the model to the observed kinetics of tegafur and 5-FU after the administration of TS-1 and UFT. Then, we simulated the plasma 5-FU profiles in patients with renal dysfunction and those after replacement of TS-1 with UFT and compared them with the observed profiles.

RESULTS

The developed model could appropriately describe the plasma concentration profiles of 5-FU and tegafur after the administration of TS-1 in patients with normal and impaired renal function.

CONCLUSION

The developed model may be useful to optimize the dosage regimen of TS-1 under various clinical conditions.

Synthesis and properties of N-nicotinoyl-2-(5-fluorouracil-1-yl)-D,L-glycine ester as a prodrug of 5-fluorouracil for rectal administration

N-Nicotinoyl-2-(5-fluorouracil-1-yl)-D,L-glycine (NFG) methyl-(NFGM), ethyl-(NFGE) and isopropyl esters (NFGIp) were synthesized and their potential as a prodrug of 5-fluorouracil (5-FU) for rectal administration was investigated. Chemical conversion proceeded either by elimination of (5-FU) or by hydrolysis of ester group. 5-FU was released from NFGIp, NFGE and NFGM 90.5%, 71.3% and 48.5% of the dose, respectively, in 80% human plasma and 79.8%, 56.3% and 31.6%, respectively, in pH 7.4 buffer solution after 48 h of incubation at 37 degrees C. Release of 5-FU occurred mainly from NFG esters but very slightly from NFG, which suggested that release of 5-FU was greatly dependent on the stability of the ester group against hydrolysis. Solubility (M) in pH 7.4 buffer solution was 0.13, 0.09 and 0.04 and apparent partition coefficient in 1-octanol/pH 7.4 buffer solution was 0.76, 1.61 and 4.2, respectively, for NFGM, NFGE and NFGIp, which were in the ranges suitable for rectal absorption. Plasma concentration (microg/mL) of NFGM, NFGE and NFGIp at 50 min after rectal administration to rats was 1.9, 4.6 and 6.7, respectively, and that for 5-FU was below the limit of detection. Their potential as prodrugs of 5-FU for rectal administration is suggested.

A pharmacokinetic-based test to prevent severe 5-fluorouracil toxicity

BACKGROUND AND OBJECTIVES

Dihydropyrimidine dehydrogenase (DPD) plays a key role in the catabolism of 5-fluorouracil (5-FU) to 5-fluoro-5,6-dihydrouracil (5-FDHU), and as such, an impairment of DPD has been recognized as an important factor for altered 5-FU and 5-FDHU pharmacokinetics, predisposing patients to the development of severe 5-FU-associated toxicity. Our objectives were to avoid severe 5-FU toxicities in patients with greatly impaired 5-FU and 5-FDHU pharmacokinetics after the administration of a reduced test dose of 5-FU and to investigate possible 5-FU or 5-FDHU pharmacokinetic parameters of the test dose related to the most common drug toxicities that affect patients after the first cycle of 5-FU chemotherapy.

METHODS

Pharmacokinetics of 5-FU/5-FDHU and DPD activity in peripheral blood mononuclear cells (PBMCs) were examined in 188 gastrointestinal cancer patients given a test dose of 5-FU, 250 mg/m2, 2 weeks before starting the planned 5-FU treatment of 370 mg/m2 plus l-folinic acid, 100 mg/m2, for 5 days every 4 weeks. Drug levels were examined by HPLC, and toxicities were graded according to World Health Organization criteria.

RESULTS

The 5-FU test dose was well tolerated in all patients. Of 188 patients, 3 (1.6%) had marked alterations of 5-FU/5-FDHU pharmacokinetics (ie, 5-FU half-life [t(1/2 beta)] >5 hours, 5-FU total body clearance [CL(TB)] <1 L x h(-1) x m(-2), and 5-FDHU time to reach maximum plasma concentration [t max] > or = 45 minutes); they were excluded from 5-FU treatments and treated with irinotecan, which was well tolerated. The plasma disposition of 5-FU in the remaining 185 patients revealed an area under the curve (AUC) of 3.73 +/- 2.18 h x microg/mL (mean +/- SD), maximum plasma concentration (Cmax) of 16.78 +/- 8.61 microg/mL, and t(1/2 beta) of 0.16 +/- 0.15 hour, whereas the CL(TB) was 65.67 +/- 31.86 L x h(-1) x m(-2). The 5-FDHU plasma profile showed a Cmax value of 3.64 +/- 1.94 microg/mL, whereas the t max value was 26.63 +/- 10.06 minutes, with an AUC value of 3.71 +/- 1.90 h x microg/mL. The PBMC DPD activity was 202.15 +/- 141.14 pmol 5-FDHU x min(-1) x mg(-1) protein (95% confidence interval, 165-239.3 pmol 5-FDHU x min(-1) x mg(-1) protein). A significant correlation between 5-FU AUC and 5-FDHU AUC was found (r = 0.5492, P < .0001), whereas a weaker correlation between PBMC DPD activity and both 5-FDHU AUC (r = 0.328, P = .0121) and 5-FDHU Cmax (r = 0.369, P = .0044) was found. Interestingly, no relationships between PBMC DPD activity and common toxicities were found, whereas 5-FDHU t max values greater than 30 minutes were associated with the risk of moderate to severe neutropenia and diarrhea (P = .0323 and P = .0138, respectively; chi-square test).

CONCLUSIONS

This study suggests a successful approach for preventing severe or life-threatening toxicities in gastrointestinal cancer patients who are candidates for standard 5-FU treatment by analyzing the 5-FU and 5-FDHU pharmacokinetic parameters after the administration of a reduced 5-FU test dose.

Total body topical 5-fluorouracil for extensive non-melanoma skin cancer

Background

Topical 5-fluorouracil 5% cream is one of␣the treatment modalities for non-melanoma skin cancer (NMSC). There is a lack of suitable therapies to treat patients with extensive NMSC. In this paper we report two patients with extensive NMSC treated by total body application of topical 5-fluorouracil 5% cream.

Observations

Topical 5-fluorouracil 5% cream was applied twice daily to the total body, including normal appearing skin. During the treatment, weekly blood samples were taken for measurement of 5-fluorouracil levels. All samples showed a 5-fluorouracil level less than the detection level of 10 µg/l. Total body 5-fluorouracil 5% cream was shown to be an effective treatment in our patients; the majority of lesions cleared in both patients.

Conclusions

In conclusion, total body topical 5-fluorouracil 5% cream application was successful in two patients with extensive NMSC. No detectable serum level of 5-fluorouracil could be determined. Pain and secondary infections were important side effects in our patients. However, in patients with extensive NMSC this treatment may be considered.

A phase I safety, pharmacological and biological study of the farnesyl protein transferase inhibitor, tipifarnib and capecitabine in advanced solid tumors

BACKGROUND

To evaluate the toxicity and pharmacological and biological properties of the farnesyl protein transferase (FPTase) inhibitor, tipifarnib (R115777, ZARNESTRAtrade mark) and capecitabine administered for 14 days every 3 weeks.

PATIENTS AND METHODS

Patients with advanced cancers received twice daily tipifarnib (100-500 mg) and capecitabine (1000-1125 mg/m(2)) for 14 days every 3 weeks. Pharmacokinetics of tipifarnib, capecitabine and 5-fluorouracil (5-FU) were determined. Peripheral blood mononuclear cells were analyzed for farnesylation of the HDJ2 chaperone protein and FPTase activity.

RESULTS

Forty-one patients received 185 courses of treatment. Diarrhea and palmar-plantar erythrodysesthesia were dose limiting at 300 mg tipifarnib/1125 mg/m(2) capecitabine b.i.d. When the capecitabine dose was fixed at 1000 mg/m(2) b.i.d., neutropenia was dose limiting at 400 and 500 mg b.i.d. of tipifarnib. Capecitabine did not affect the pharmacology of tipifarnib at 100-300 mg b.i.d., although tipifarnib significantly increased the C(max) of 5-FU at 400 mg b.i.d. HDJ2 farnesylation and FPTase activity decreased between 200 and 400 mg b.i.d. doses of tipifarnib, without a dose-response relationship. Five patients demonstrated partial remissions and 11 patients maintained prolonged stable disease.

CONCLUSIONS

Tipifarnib and capecitabine are well tolerated at 300 mg/1000 mg/m(2) b.i.d., respectively, resulting in biologically relevant plasma concentrations and antitumor activity. The recommended dose for further disease-focused studies is 300 mg b.i.d. tipifarnib and 1000 mg/m(2) b.i.d. capecitabine, given for 14 days every 3 weeks.

Correlation between the urinary dihydrouracil-uracil ratio and the 5-FU plasma concentration in patients treated with oral 5-FU analogs

BACKGROUND

The determination of dihydropyrimidine dehydrogenase (DPD) deficiency is important in avoiding severe 5-fluorouracil (FU) toxicity. The dihydrouracil (UH2)-uracil (Ura) ratio (UH2/Ura) in plasma might be an important indicator of the risk of 5-FU catabolic deficiency. In order to clarify this possibility, the pyrimidine metabolites and the UH2/Ura were measured in urine and the plasma level of 5-FU was evaluated in patients with gastric and colorectal cancer.

PATIENTS AND METHODS

Patients with primary gastric (n=14) and colorectal (n=8) cancer who had undergone surgery were recruited in this study. These patients were divided into the S-1 treatment group, which drug is a novel oral formulation of tegafur, oxonic acid and 5-chloro-2, 4-dihydroxypyridine (CDHP) (n=14) and a group receiving other drugs which include UFT (Uracil/Tegafur) or oral doxifluridine (n=8). The urinary levels of UH2 and Ura were measured by high-performance liquid chromatography (HPLC) using column swiching. The plasma level of 5-FU was assessed by gas chromatography-mass spectrometry (GC-MS).

RESULTS

The UH2/Ura or UH2/Ura (treated/no treated) in the S-1 group significantly decreased in comparison to that in the other-drug group and the plasma 5-FU concentration in the S-1 group significantly increased compared to that in the group treated with other drugs. The plasma 5-FU concentration levels significantly indicated a positive correlation with urinary Ura. Moreover, UH2/Ura treated with 5-FU analogs or UH2/Ura (treated/no treated) significantly showed a negative correlation with the plasma 5-FU concentration levels.

CONCLUSION

Our findings indicate that either urinary Ura, the UH2/Ura or UH2/Ura (treated/no treated) can predict the plasma 5-FU concentration levels or DPD deficiencies.

[Correlative analysis between serum dihydropyrimidine dehydrogenase, activity, concentration of 5-fluorouracil and adverse events in the treatment of advanced gastric cancer patients]

BACKGROUND & OBJECTIVE

Toxicities and their severities vary among advanced gastric cancer patients when they receive the same regimen containing continuous infusion of 5-fluorouracil (5-FU). Dihydropyrimidine dehydrogenase (DPD) is the key rate-limiting enzymes which is closely related to toxicities of 5-FU in chemotherapy. This study was to explore the relationship between activity of DPD and concentration of 5-FU, and their correlation to adverse events among advanced gastric cancer patients treated with the same regimen containing 5-FU continuous infusion.

METHODS

Patients received the same regimen (intravenous injection of paclitaxel 75 mg/m(2), leucovorin 200 mg/m(2) and 5-FU 375 mg/m(2), continuous infusion of 5-FU 2.5 g/m2 for 46 hours every two weeks). The peripheral blood was collected from 36 patients with advanced gastric cancer before and after chemotherapy to detect the activity of DPD and concentration of 5-FU by high-performance liquid chromatography (HPLC). Adverse events were assessed every cycle.

RESULTS

Serum activity of DPD revealed a unimodel distribution, which globally fits to a guassian distribution (range 1.56-6.01). Mean and median DPD activity values were 2.38 and 2.13, respectively. No total DPD deficiency was found in the patients. The concentration of 5-FU varied from 179.2 microg/L to 1 589.2 microg/L, which demonstrated normality distribution after a logarithmic transformation was applied. The DPD activity was inversely correlated with 5-FU concentration (r=-0.376, P=0.024). The patients with low activity of DPD were more frequently suffering from severe diarrhea, mucositis, and myelosuppression. And high level of 5-FU concentration led to the increase of adverse events.

CONCLUSION

Pre-chemotherapy DPD activity and 5-FU concentration during chemotherapy vary among gastric cancer patients, which may help to prevent severe toxicities during the treatment.

Pharmacokinetics of S-1 in patients with peritoneal dissemination of gastric cancer

The response of gastric cancer with peritoneal dissemination to systemic chemotherapy may be negatively affected by poor drug delivery due to the blood-peritoneal barrier. However, S-1 has been reported to be effective. We examined the pharmacokinetics of S-1 in 14 patients who had gastric cancer with peritoneal dissemination. S-1 was given from the morning of the day before surgery to the morning of surgery. Concentrations of 5-fluorouracil (5-FU) and gimeracil (CDHP) were measured in the serum, ascites, disseminated peritoneal nodes, and normal peritoneum. There was a strong correlation between 5-FU and CDHP concentrations in peritoneal tissues. The concentrations of 5-FU and CDHP in the serum were similar to those in ascites. The concentration of 5-FU was significantly higher in disseminated nodes than in the normal peritoneum. After administration of S-1 to gastric cancer patients with peritoneal dissemination, 5-FU and CDHP in the serum linearly pass through the peritoneum and enter the ascites. High concentrations of 5-FU selectively penetrate disseminated peritoneal cells.