DPD functional tests in plasma, fresh saliva and dried saliva samples as predictors of 5-fluorouracil exposure and occurrence of drug-related severe toxicity.

OBJECTIVE: to evaluate plasma and salivary uracil (U) to dihydrouracil (UH2) ratios as tools for predicting 5-fluorouracil systemic exposure and drug-related severe toxicity, and clinically validate the use of dried saliva spots (DSS) as an alternative sampling strategy for dihydropyrimidine dehydrogenase (DPD) deficiency assessment. METHODS: Pre-chemotherapy plasma, fresh saliva and DSS samples were obtained from gastrointestinal patients (N = 40) for measurement of endogenous U and UH2 concentrations by LC-MS/MS. A second plasma sample collected during 5FU infusion was used for 5FU area under the curve (AUC) determination by HPLC-DAD. Data on toxicity was reported according to CTCAE. RESULTS: 15% of the patients developed severe 5FU-related toxicity, with neutropenia accounting for 67% of the cases. U, UH2 and [UH2,]/[U] were highly correlated between fresh and dried saliva samples (rs = 0.960; rs = 0.828; rs = 0.910, respectively). 5FU AUC ranged from 11.3 to 37.31 mg h L-1, with 46.2% of under-dosed and 10.3% over-dosed patients. The [UH2]/[U] ratios in plasma, fresh saliva and dried saliva samples were moderately correlated with 5FU AUC and adverse events grade, indicating a partial contribution of the variables to drug exposure (r = -0.412, rs = -0.373, rs = 0.377) and toxicity (r = -0.363, rs = -0.523, rs = 0.542). Metabolic ratios were lower in patients with severe toxicity (P < .01 salivary ratios, and P < .5 plasma ratios), and 5FU AUC were in average 47% higher in this group than in moderate toxicity. The diagnostic performance of [UH2]/[U] ratios in fresh saliva and DSS for the identification of patients with severe toxicity were comparable. CONCLUSIONS: The [UH2]/[U] metabolic ratios in plasma, fresh saliva and DSS were significantly associated with 5FU systemic exposure and toxicity degree. This study also demonstrated the applicability of DSS as alternative sampling for evaluating DPD activity.

Influence of metastatic disease on the usefulness of uracil pharmacokinetics as a screening tool for DPD activity in colorectal cancer patients.

PURPOSE: Dihydropyrimidine dehydrogenase (DPD) deficiency can lead to severe toxicity in patients treated with a standard dose of a fluoropyrimidine such as 5-fluorouracil or capecitabine (CAP). Administration of oral uracil and subsequent measurement of uracil and dihydrouracil (DHU) plasma concentrations has been used to identify patients with DPD deficiency. Liver metastasis might influence systemic DPD activity. The aim of the study was to investigate the effect of metastatic disease on the pharmacokinetics of uracil and DHU after oral administration of uracil. METHODS: 500 mg/m(2) uracil was administered orally to 12 subjects with stages II-III colorectal cancer (CRC) who were treated in the adjuvant setting and to 12 subjects with stage IV metastasized CRC, all treated with CAP containing therapy. All subjects had a normal DPD activity defined as >6 nmol/mg/h determined in peripheral blood mononuclear cells. RESULTS: The mean uracil clearance [CL 51.7 (SD 6.4) vs. 46.7 (SD 13.0) l/h], area under the curve [AUC0-220min 20.6 (SD 6.4) vs. 21.0 (SD 5.7) h mg/l], elimination half-life [t 1/2 21 (SD 7) vs. 21 (SD 8) min], maximum concentration time [T max 27 (SD 9) vs. 25 (SD 9) min], volume of distribution [V 26.58 (SD 10.11) vs. 21.10 (SD 8.48) l] and the elimination constant [k el 2.01 (SD 0.56) vs. 2.41 (SD 0.72) h(-1)] did not differ significantly (p > 0.05) non-metastatic CRD versus metastatic CRC. CONCLUSIONS: Metastasis does not alter uracil pharmacokinetics and is similar in CRC patients with and without metastasis. Therefore, the uracil test dose could be used as a DPD phenotype test in both adjuvantly treated and metastatic CRC patients using similar cutoff criteria to identify patients with DPD deficiency.

Prognostic impact of blood biomarkers TS and DPD in neoadjuvant-treated esophageal cancer patients.

BACKGROUND/AIM: The prognostic value of TS (thymidylate synthase) and DPD (dihydropyrimidine dehydrogenase) RNA expression in the blood of patients with esophageal cancer is not known. The aim of the present study was to evaluate the significance of these molecular alterations in the blood as a prognostic marker for patients with neoadjuvant-treated esophageal cancer. PATIENTS AND METHODS: A total of 29 patients with locally advanced esophageal cancer (cT3-T4, Nx, M0) were enrolled in this prospective study. All patients received neoadjuvant chemoradiation followed by a transthoracic resection (curative transthoracic en bloc esophagectomy, RO). Peripheral blood samples were drawn before initiation of therapy. The analysis was performed using quantitative real-time-polymerase chain reaction (RT-PCR). The histomorphological regressions grading after neoadjuvant therapy was defined as follows: major response (MaR)=less than 10% vital tumor tissue, minor response (MiR)=more than 10% vital tumor tissue. RESULTS: Nineteen out of 29 patients (65.5%) had a MiR and 10 (34.5%) had a MaR. The median survival of patients was 2.08 years (range=0.15-4.53). Among the tested genes, the RNA expression of TS was significantly associated with prognosis of patients. Patients with TS expression above 0.78 had a median survival of 1.1 years (range=0.21-3.96) compared to 2.6 years (range=0.15 to 4.53) in patients with TS expression lower than 0.78 (p=0.031, log rank test). There was no association between clinical variables (e.g., tumor stage, gender, age, etc.) and the RNA expression of TS in the serum. CONCLUSION: The RNA expression of TS in the blood is a potential prognostic marker in patients with neoadjuvant-treated esophageal cancer. The significance of these molecular alterations as non-invasive prognostic marker for esophageal cancer should be evaluated in prospective studies.

Roles of thymidylate synthase and dihydropyrimidine dehydrogenase expression in blood as predictors of response to multimodal therapy in esophageal cancer.

BACKGROUND: Thymidylate synthetase (TS) and dihydropyrimidine dehydrogenase (DPD) RNA expression in peripheral blood was examined as a noninvasive molecular predictor of response to neoadjuvant radiochemotherapy in patients with locally advanced cancer of the esophagus. METHODS: Blood samples were drawn from 29 patients with esophageal cancer (10 squamous cell carcinomas and 19 adenocarciomas) before neoadjuvant radiochemotherapy. After extraction of cellular tumor RNA from blood samples, quantitative expression analysis of TS and DPD was performed with quantitative real-time reverse-transcription polymerase chain reaction. RESULTS: Twenty of 29 (68%) of patients had a minor histopathologic response, and 9 of 29 (32%) had a major response to neadjuvant radiochemotherapy. RNA expression in the blood of patients was detectable for TS in 86%, for DPD in 97%, and in 100% for ß-actin. No significant associations were detected between TS and DPD expression levels and clinical variables of the patients. A high expression level for TS was associated with a minor response to neoadjuvant treatment (P = .046), while there was no significant association between DPD and response to therapy. Combined analysis of TS and DPD expression increased the specificity for the prediction of response to 100%. No major responder to therapy had high expression levels for both genes in their peripheral blood. CONCLUSION: Quantitation of TS and DPD in peripheral blood may be a highly specific analysis to identify a subset of patients who do not respond to neoadjuvant radiochemotherapy and may therefore prevent expensive, noneffective, and potentially harmful therapies in a substantial number of patients with esophageal cancer.

Impact of SHMT1 polymorphism on the clinical outcome of patients with metastatic colorectal cancer treated with first-line FOLFIRI+bevacizumab.

The impact of thymidylate synthase (TYMS), methylenetetrahydrofolate reductase (MTHFR), and serine hydroxymethyltransferase 1 (SHMT1) gene polymorphisms and that of dihydropyrimidine dehydrogenase (DPD) enzyme activity, serum total homocysteine level, and estimated serum creatinine clearance on first-line 5-fluorouracil, leucovorin, irinotecan, and bevacizumab (FOLFIRI+bevacizumab) regimen efficacy in metastatic colorectal cancer patients was investigated. DNA was extracted from peripheral blood mononuclear cells. Genotyping was performed for TYMS 5'UTR variable number tandem repeat, TYMS 3'UTR ins/del, MTHFR C677T, and SHMT1 C1420T polymorphisms. The DPD activity of peripheral blood mononuclear cells was also determined. The univariate and multivariate analyses demonstrated that the SHMT1 1420T allele was associated with better response (P=0.025) and longer progression-free survival (PFS) (P=0.00004) and overall survival (OS) (P=0.034). Grade ≥2 hypertension was also an independent prognostic factor of longer progression-free survival and OS. Bevacizumab-related hypertension might be a predictive marker of treatment efficacy (P=0.0002 for OS) in the case of wild (CC) SHMT1 1420 genotypes only.

Determination of 5-fluorouracil and dihydrofluorouracil levels by using a liquid chromatography-tandem mass spectrometry method for evaluation of dihydropyrimidine dehydrogenase enzyme activity.

PURPOSE: 5-Fluorouracil (5-FU), acting as a pyrimidine antagonist, is a major chemotherapy drug used for the treatment of tumors such as gastrointestinal, breast, ovary, and head and neck cancers. The key and rate-limiting enzyme in 5-FU catabolism is dihydropyrimidine dehydrogenase (DHPDH), whose partial or complete deficiency exposes to a severe 5-FU toxicity in patients. The determination of DHPDH activity in patients before the treatment and setting up a personalized therapy for each patient receiving the drug can help us to prevent the possible risk of toxicity. METHODS: To isolate peripheral blood mononuclear cells (PBMCs), EDTA-anticoagulated blood samples were collected from randomly selected 47 patients and examined for 5-FU and its metabolite dihydrofluorouracil (FUH2) by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) to observe DHPDH activity at different intervals (0 and 4th hour) indirectly. RESULTS: Intra-assay and interassay CV % values of samples from the measurements of the modified methods are found 1.3-11.9, 2.3-9.4 for 5-FU and 3.1-14.4, 3.3-12.6 for FUH2, respectively. The reference values derived from 45 patients treated with 5-FU are 1.84 ± 0.34 ug/gr protein for 5-FU, 40.15 ± 11.43 ng/gr protein for FUH2, respectively. FUH2/5-FU ratio is 21.9 ± 3.72. In addition, the results determined from two patients, in which the lack of DHPDH is considered, were 3.24 and 4.16 ug/gr protein for 5-FU, 4.1 and 6.7 ng/gr protein for FUH2. FUH2/5-FU ratio is 1.26 and 1.61. CONCLUSION: The measurements of 5-FU, FUH2, and especially their ratio (FUH2/5-FU) by the modified LC-MS/MS method could be used to determine DHPDH enzyme activity.

HPLC-electrospray tandem mass spectrometry for rapid determination of dihydropyrimidine dehydrogenase activity.

BACKGROUND: Patients with a partial dihydropyrimidine dehydrogenase (DPD) deficiency have an increased risk of developing severe 5-fluorouracil-associated toxicity. We developed a rapid and specific method to measure the DPD activity in peripheral blood mononuclear cells using HPLC tandem-mass spectrometry (HPLC-MS/MS). METHODS: The activity of DPD was measured with thymine as the substrate, followed by reversed-phase HPLC combined with electrospray ionization MS/MS and detection of the product dihydrothymine with multiple-reaction monitoring. Stable-isotope labeled dihydrothymine was used as the internal standard. RESULTS: Dihydrothymine was measured within an analytical run of 10 min, with a lower limit of quantification of 54 microg/L (0.4 micromol/L). The intraassay and interassay variations of the DPD activity assay were both <7%. A linear correlation (R(2) = 0.980; P <0.001) was observed between the HPLC-MS/MS data and those obtained with a reference method using radiolabeled thymine. There were no systematic differences between the 2 methods, and both methods yielded similar results. CONCLUSION: The analysis of the DPD activity with HPLC-MS/MS is rapid, accurate, and sufficiently sensitive to be used as a screening method for patients with a DPD deficiency.

A case of hepatocellular carcinoma with multiple lung, spleen, and remnant liver metastasis successfully treated by combination chemotherapy with the novel oral DPD-inhibiting chemotherapeutic drug S-1 and interferon-alpha.

A 54-year-old man was admitted Osaka University Hospital for hepatocellular carcinoma (HCC) with portal vein thrombus and multiple intrahepatic metastases that extended to the bilateral lobes of the liver. He underwent multimodal therapy, including extended left lobectomy followed by intra-arterial 5-fluorourcil (5-FU) infusion chemotherapy combined with subcutaneous interferon-alpha (IFN-alpha) to treat the lesions in the residual liver. Seven months after the initial resection, recurrent tumors in the spleen, lung, and residual liver were detected by follow-up examination. We started a new regimen of per oral administration of S-1 and subcutaneous IFN-alpha injection, because the combined therapy with intra-arterial 5-FU infusion was not considered effective for distant metastases. After two cycles of S-1 and IFN-alpha, the metastatic tumor in the spleen and the recurrence in the residual liver had disappeared, and the diagnosis was complete remission with no adverse effect; the pulmonary metastasis showed a partial response, and was finally resected. This patient is still alive with no recurrence 32 months after initial hepatic resection. This outcome suggests that combination therapy with S-1 and IFN-alpha may be a promising treatment modality against advanced HCC with distant metastasis.

[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.

Increased prevalence of dihydropyrimidine dehydrogenase deficiency in African-Americans compared with Caucasians.

PURPOSE: African-American patients with colorectal cancer were observed to have increased 5-fluorouracil (5-FU)-associated toxicity (leukopenia and anemia) and decreased overall survival compared with Caucasian patients. One potential source for this disparity may be differences in 5-FU metabolism. Dihydropyrimidine dehydrogenase (DPD), the initial and rate-limiting enzyme of 5-FU catabolism, has previously been shown to have significant interpatient variability in activity. Several studies have linked reduced DPD activity to the development of 5-FU toxicity. Although the distribution of DPD enzyme activity and the frequency of DPD deficiency have been well characterized in the Caucasian population, the distribution of DPD enzyme activity and the frequency of DPD deficiency in the African-American population are unknown. EXPERIMENTAL DESIGN: Healthy African-American (n=149) and Caucasian (n=109) volunteers were evaluated for DPD deficiency using both the [2-(13)C]uracil breath test and peripheral blood mononuclear cell DPD radioassay. RESULTS: African-Americans showed significantly reduced peripheral blood mononuclear cell DPD enzyme activity compared with Caucasians (0.26+/-0.07 and 0.29+/-0.07 nmol/min/mg, respectively; P=0.002). The prevalence of DPD deficiency was 3-fold higher in African-Americans compared with Caucasians (8.0% and 2.8%, respectively; P=0.07). African-American women showed the highest prevalence of DPD deficiency compared with African-American men, Caucasian women, and Caucasian men (12.3%, 4.0%, 3.5%, and 1.9%, respectively). CONCLUSION: These results indicate that African-Americans, particularly African-American women, have significantly reduced DPD enzyme activity compared with Caucasians, which may predispose this population to more 5-FU toxicity.

The uracil breath test in the assessment of dihydropyrimidine dehydrogenase activity: pharmacokinetic relationship between expired 13CO2 and plasma [2-13C]dihydrouracil.

PURPOSE: Dihydropyrimidine dehydrogenase (DPD) deficiency is critical in the predisposition to 5-fluorouracil dose-related toxicity. We recently characterized the phenotypic [2-(13)C]uracil breath test (UraBT) with 96% specificity and 100% sensitivity for identification of DPD deficiency. In the present study, we characterize the relationships among UraBT-associated breath (13)CO(2) metabolite formation, plasma [2-(13)C]dihydrouracil formation, [2-(13)C]uracil clearance, and DPD activity. EXPERIMENTAL DESIGN: An aqueous solution of [2-(13)C]uracil (6 mg/kg) was orally administered to 23 healthy volunteers and 8 cancer patients. Subsequently, breath (13)CO(2) concentrations and plasma [2-(13)C]dihydrouracil and [2-(13)C]uracil concentrations were determined over 180 minutes using IR spectroscopy and liquid chromatography-tandem mass spectrometry, respectively. Pharmacokinetic variables were determined using noncompartmental methods. Peripheral blood mononuclear cell (PBMC) DPD activity was measured using the DPD radioassay. RESULTS: The UraBT identified 19 subjects with normal activity, 11 subjects with partial DPD deficiency, and 1 subject with profound DPD deficiency with PBMC DPD activity within the corresponding previously established ranges. UraBT breath (13)CO(2) DOB(50) significantly correlated with PBMC DPD activity (r(p) = 0.78), plasma [2-(13)C]uracil area under the curve (r(p) = -0.73), [2-(13)C]dihydrouracil appearance rate (r(p) = 0.76), and proportion of [2-(13)C]uracil metabolized to [2-(13)C]dihydrouracil (r(p) = 0.77; all Ps < 0.05). CONCLUSIONS: UraBT breath (13)CO(2) pharmacokinetics parallel plasma [2-(13)C]uracil and [2-(13)C]dihydrouracil pharmacokinetics and are an accurate measure of interindividual variation in DPD activity. These pharmacokinetic data further support the future use of the UraBT as a screening test to identify DPD deficiency before 5-fluorouracil-based therapy.

Physiologically based pharmacokinetic modelling of the three-step metabolism of pyrimidine using C-uracil as an in vivo probe.

AIMS: Approximately 80% of uracil is excreted as beta-alanine, ammonia and CO2 via three sequential reactions. The activity of the first enzyme in this scheme, dihydropyrimidine dehydrogenase (DPD), is reported to be the key determinant of the cytotoxicity and side-effects of 5-fluorouracil. The aim of the present study was to re-evaluate the pharmacokinetics of uracil and its metabolites using a sensitive assay and based on a newly developed, physiologically based pharmacokinetic (PBPK) model. METHODS: [2-(13)C]Uracil was orally administrated to 12 healthy males at escalating doses of 50, 100 and 200 mg, and the concentrations of [2-(13)C]uracil, [2-(13)C]5,6-dihydrouracil and beta-ureidopropionic acid (ureido-(13)C) in plasma and urine and (13)CO2 in breath were measured by liquid chromatography-tandem mass spectrometry and gas chromatograph-isotope ratio mass spectrometry, respectively. RESULTS: The pharmacokinetics of [2-(13)C]uracil were nonlinear. The elimination half-life of [2-(13)C]5,6-dihydrouracil was 0.9-1.4 h, whereas that of [2-(13)C]uracil was 0.2-0.3 h. The AUC of [2-(13)C]5,6-dihydrouracil was 1.9-3.1 times greater than that of [2-(13)C]uracil, whereas that of ureido-(13)C was 0.13-0.23 times smaller. The pharmacokinetics of (13)CO2 in expired air were linear and the recovery of (13)CO2 was approximately 80% of the dose. The renal clearance of [2-(13)C]uracil was negligible. CONCLUSION: A PBPK model to describe (13)CO2 exhalation after orally administered [2-(13)C]uracil was successfully developed. Using [2-(13)C]uracil as a probe, this model could be useful in identifying DPD-deficient patients at risk of 5-fluorouracil toxicity.

Recurrence and 5-FU sensitivity of stage III/Dukes' C colorectal cancer with occult neoplastic cells in lymph node sinuses.

In 72 patients without occult neoplastic cells (ONCs) in their lymph node sinuses, the 5-year relapse-free survival (RFS) rate and overall survival (OS) rate were 71.3% and 69.2%, respectively. In 33 patients with ONCs, the 5-year RFS rate and OS rate were 33.9% and 31.3%, respectively. There was a marked difference of survival between the two groups (p=0.0001 and p=0.0003). The metastatic lymph nodes of the 33 ONC-positive patients had high and low levels of thymidilate synthase (TS) expression in 38.1% (8/21) and 61.9% (13/21) of the recurrence group (n=21), respectively, while high and low levels of dihydropyrimidine dehydrogenase (DPD) expression were found in 38.1% (8/21) and 61.9% (13/21), respectively. In the non-recurrence group (n=12), high and low levels of TS or DPD expression were detected in 58.3% (7/12) and 41.7% (5/12) versus 16.7% (2/12) and 83.3% (10/12), respectively. Patients with high TS and low DPD expression accounted for 9.5% (2/21) of the recurrence group and 50.0% (6/12) of the non-recurrence group (p<0.01). These results suggest that ONCs are clearly associated with the 5-year RFS and OS rates. Unlike the non-recurrence group, the recurrence group of ONC-positive patients with Dukes' C colorectal cancer is unlikely to respond well to treatment with 5-FU plus LV and require combination chemotherapy based on CPT-11 and/or L-OHP.

Recurrence and 5-FU sensitivity of stage II/Dukes' B colorectal cancer with occult neoplastic cells in lymph node sinuses.

In 103 patients without occult neoplastic cells (ONCs) in the lymph node sinuses, the 5-year relapse-free survival (RFS) rate and overall survival (OS) rate were 90.2% and 91.8%, respectively. In 21 patients with ONCs, the 5-year RFS and OS rates were 34.9% and 62.3%, respectively. There were marked differences of survival between the two groups (p=0.0000 and p=0.0003). In the primary tumors of the 21 ONC-positive patients, high and low TS levels were found in 46.2% (6/13) and 53.8% (7/13) of the recurrence group (n=13), respectively. High and low DPD levels were found in 23.1% (3/13) and 76.9% (10/13), respectively. In the non-recurrence group (n=8), high and low TS or DPD levels were found in 75.0% (6/8) and 25.0% (2/8) versus 12.5% (1/8) and 87.5% (7/8), respectively. The percentage of patients with high TS and low DPD levels was 23.1% (3/13) in the recurrence group and 62.5% (5/8) in the non-recurrence group (p=0.07). These results suggest that the presence of ONCs had a clear association with the 5-year RFS and OS rates. The recurrence group of ONC-positive patients with stage II/Dukes' B colorectal cancer was unlikely to be highly responsive to 5-FU-based treatment, thus requiring multi-combination chemotherapy using CPT-11 and/or L-OHP.

Circadian rhythm in dihydropyrimidine dehydrogenase activity and reduced glutathione content in peripheral blood of nasopharyngeal carcinoma patients.

Dihydropyrimidine dehydrogenase (DPD) is a rate-limiting enzyme of 5-fluorouracil (5-FU) catabolism. Glutathione (GSH) is a tripeptide involved in platinum complex detoxification. This study explored the circadian rhythms of DPD activity and GSH concentration in the peripheral blood of 16 patients with histologically proven nasopharyngeal carcinoma (NPC) in order to guide the establishment of chronotherapeutic schedules for this cancer. DPD activity and GSH concentration were determined by high performance liquid chromatography (HPLC). Both variables displayed significant circadian rhythms (Cosinor analysis: p = 0.009 and 0.012, respectively). Peak DPD activity occurred at about 02:30 h; whereas, peak GSH concentration occurred around 12:40 h. The differences between the peak and nadir mean values were 25.5% and 38.7%, respectively. The study showed that the circadian rhythms in DPD activity and GSH concentration in Chinese NPC are similar to those reported for western patients with colorectal cancer, despite the differences in race and kinds of cancer. These findings imply that the chronotherapeutic schedule of 5-FU and platinum used to treat European colorectal cancer patients probably is applicable to Chinese NPC patients.

[Relationship of serum level of dihydropyrimidine dehydrogenase and serum concentration of 5-fluorouracil to treatment response and adverse events in colorectal cancer patients].

BACKGROUND & OBJECTIVE: Toxicities and response are different when patients with advanced colorectal cancer were treated with standard FOLFOX6 regimen. Serum level of dihydropyrimidine dehydrogenase (DPD) relates to efficacy and toxicities of chemotherapy containing 5-fluorouracil (5-FU). This study was to explore relationship of DPD to serum concentration of 5-FU in colorectal cancer patients treated with FOLFOX6 regimen, and their correlation to treatment response and adverse events. METHODS: Serum level of DPD in 72 patients with colorectal cancer was detected by high-performance liquid chromatography (HPLC) before chemotherapy. Serum concentration of 5-FU at steady state was detected by HPLC after patients received FOLFOX6 regimen. Treatment response and adverse events in the patients were assessed. RESULTS: Serum levels of DPD were normally distributed in 72 patients (ranged 1.55-5.94), while serum concentrations of 5-FU at steady state were not (ranged 141.1-1 741.9 microg/L). Serum level of DPD was negatively correlated with serum concentration of 5-FU (r=-0.460, P < 0.01). Occurrence of adverse events was lower when 5-FU concentration was less than 600 microg/L than when 5-FU concentration was more than 600 microg/L (P < 0.05). The mean serum concentration of 5-FU was significantly higher in patients with complete response and partial response than in patients with steady disease, and progressive disease (513.9 microg/L vs. 409.8 microg/L, and 259.3 microg/L, P < 0.05). Serum level of DPD was lower in patients suffered oral mucositis and diarrhea of grade II-IV than in patients suffered oral mucositis and diarrhea of grade 0-I (P=0.016, P=0.047). Serum level of DPD had no relation with treatment response of the patients (r=0.312, P=0.078). CONCLUSIONS: DPD level and serum 5-FU concentration vary a lot among patients with colorectal cancer. DPD level negatively correlates with serum 5-FU concentration. Serum concentration of 5-FU correlates with treatment effect and toxicities.

Effects of TS-1 on peritoneal dissemination of gastric cancer in nude mice.

BACKGROUND/AIMS: We investigated the effects of TS-1 on the survival of nude mice developing peritoneal dissemination of gastric cancer. METHODOLOGY: MKN-45 cells were injected into the peritoneal cavity of nude mice and a model of peritoneal dissemination was developed. TS-1 was administered orally every day from day 1 to day 10 or day 10 to day 19. RESULTS: Survival time of these treatment groups was significantly longer than untreated controls. In a pharmacokinetic study, TS-1 was administered on day 10 and the 5-fluorouracil levels were retained and maintained for a longer time, in the ascites and tumor than in plasma. The area under the concentration curve for 5-FU in the tumor was higher, than in plasma or ascites. CONCLUSIONS: TS-1 could be effective in treating peritoneal dissemination of gastric cancer, due to the supply of 5-fluorouracil in the tumor by systemic and intraperitoneal circulation.