Rapid identification of dihydropyrimidine dehydrogenase deficiency by using a novel 2-13C-uracil breath test.

PURPOSE: Dihydropyrimidine dehydrogenase (DPD)-deficient cancer patients have been shown to develop severe toxicity after administration of 5-fluorouracil. Routine determination of DPD activity is limited by time-consuming and labor-intensive methods. The purpose of this study was to develop a simple and rapid 2-(13)C-uracil breath test, which could be applied in most clinical settings to detect DPD-deficient cancer patients. EXPERIMENTAL DESIGN: Fifty-eight individuals (50 "normal," 7 partially, and 1 profoundly DPD-deficient) ingested an aqueous solution of 2-(13)C-uracil (6 mg/kg). (13)CO(2) levels were determined in exhaled breath at various time intervals up to 180 min using IR spectroscopy (UBiT-IR(300)). DPD enzyme activity and DPYD genotype were determined by radioassay and denaturing high-performance liquid chromatography, respectively. RESULTS: The mean (+/-SE) C(max), T(max), delta over baseline values at 50 min (DOB(50)) and cumulative percentage of (13)C dose recovered (PDR) for normal, partially, and profoundly DPD-deficient individuals were 186.4 +/- 3.9, 117.1 +/- 9.8, and 3.6 DOB; 52 +/- 2, 100 +/- 18.4, and 120 min; 174.1 +/- 4.6, 89.6 +/- 11.6, and 0.9 DOB(50); and 53.8 +/- 1.0, 36.9 +/- 2.4, and <1 PDR, respectively. The differences between the normal and DPD-deficient individuals were highly significant (all Ps <0.001). CONCLUSIONS: We demonstrated statistically significant differences in the 2-(13)C-uracil breath test indices (C(max), T(max), DOB(50), and PDR) among healthy and DPD-deficient individuals. These data suggest that a single time-point determination (50 min) could rapidly identify DPD-deficient individuals with a less costly and time-consuming method that is applicable for most hospitals or physicians' offices.     

Sequential 5-fluorouracil and leucovorin in patients with advanced symptomatic gastrointestinal cancer

50 patients with advanced symptomatic gastrointestinal cancer were treated with sequential 5-fluorouracil (5-FU)/leucovorin. Patients received an intravenous bolus injection of 5-FU (500 or 600 mg/m²) and leucovorin 30–40 min later, either 50 mg (41 patients) or 200 mg (9 patients). Treatment was given in repeated courses either once weekly or on 2 consecutive days every other week until progression. Toxicity was mild with the lower leucovorin dose, although grade 2 toxicity, particularly diarrhoea, occurred in 27 (66%) patients. All patients receiving the higher leucovorin dose had grade 2–4 toxicity. Toxicity was less with the lower 5-FU dose. Out of 40 patients with colorectal cancer, 34 received leucovorin 50 mg and 6 received 200 mg. Partial response occurred in 10 (29%) and 1 of these patients, respectively. This sequential 5-FU and intermediate-dose leucovorin regimen has acceptable toxicity and a definite anti-tumour activity.     

Adriamycin, CCNU, and 5-fluorouracil in patients with advanced gastrointestinal cancer

Forty-one patients with measurable advanced gastrointestinal malignancy were treated with a combination of Adriamycin (doxorubicin), 5-FU (5-fluorouracil), and CCNU (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea). The response to therapy was evaluated every eight weeks. In addition to standard clinical examinations and laboratory tests to evaluate toxicity, 31 patients were asked to rank both the expected and experienced negative effects of the treatment. Although both patients with hepatocellular cancer and the patient with a soft tissue sarcoma responded to the regimen, only 1 of 38 patients with adenocarcinoma had a favourable response. The clinically measurable toxicity, principally to the gastrointestinal tract and bone marrow, was relatively mild. However, the patients' subjective evaluation of their treatment made the side effects appear more significant. The results suggest that this regimen deserves further evaluation in patients with hepatocellular cancer and soft tissue sarcomas.     

Outpatient chemotherapy with infusional 5-fluorouracil in advanced gastrointestinal cancer

These studies were designed to evaluate the efficacy, toxicity, and resulting quality of life (QOL) of outpatient chemotherapy with infusional 5-FU for advanced gastrointestinal cancer. Schedule, sch. A: Treatment consisted of CI 5-FU 200 mg/m2/day, days 1-28, IVB Leucovorin 20 mg/m2 q week. Fifteen patients with advanced gastrointestinal cancer were treated to maintain the efficacy of prior inpatient chemotherapy. Twenty-one patients treated with adjuvant chemotherapy were added to evaluate toxicity and QOL. The mean time to progression (TTP) was 2.6 months. Grade 2 toxicities were seen, including mucositis (23%) and diarrhea (7%). Hand-foot syndrome was seen 60% of patients. The mean QOL score was 89.5 +/- 7.8. Sch.B: Treatment consisted of weekly 24 h infusion of 5-FU 2,600 mg/m2. 5-FU was administered using a Groshong catheter and Baxter infusor LV5 (5 ml/hr). Nine patients with advanced gastrointestinal cancer were treated. Twenty-one patients were treated with adjuvant chemotherapy. The mean TTP was 3.6 month. Grade 2 toxicities were seen, including leucocytopenia (7%), mucositis (3%), diarrhea (10%), and nausea and vomiting (10%). The mean QOL score was 82.6 +/- 10.7. In conclusion, both 5-FU schedules are feasible for outpatient chemotherapy for advanced gastrointestinal cancer.     

Relationship between 5-fluorouracil disposition, toxicity and dihydropyrimidine dehydrogenase activity in cancer patients

Background:Previous work demonstrated that 5-fluorouracil(5-FU) metabolism is a critical factor for treatment tolerability. Inorder to study the predictivity of pharmacokinetics with respect to theoccurrence of 5-FU toxicity, this study investigates the relationshipbetween the pharmacokinetics of 5-FU and its metabolite5-fluoro-5,6-dihydrouracil (5-FDHU), dihydropyrimidine dehydrogenase(DPD) activity in peripheral blood mononuclear cells (PBMNC) andtreatment tolerability. Patients and methods:Pharmacokinetics and metabolismof 5-FU and activity of DPD in PBMNC were examined in110 colorectal cancer patients given adjuvant 5-FU 370mg/m² plus L-folinic acid 100 mg/m² for five daysevery four weeks. Drug levels were examined by HPLC, while toxicitieswere graded according to WHO criteria. Results:DPD activity in patients with mild toxicities (WHOgrade 1) was 197.22 ± 11.34 pmol of 5-FDHU/min/mg of protein,while in five patients with grade 3–4 gastrointestinal toxicity,DPD ranged from low to normal values (range 31.12–182.37pmol/min/mg of protein). In these patients, 5-FU clearance (CL) waslower (range 14.12–25.17 l/h/m²), and the area underthe curve (AUC) was higher (range 14.70–26.20 h×µg/ml)than those observed in 84 patients with mild toxicities (CL, 56.30± 3.60 l/h/m²; AUC, 7.91 ± 0.44h×µg/ml). The severity of adverse events was associated withincreased 5-FU/5-FDHU AUC ratio and reduced 5-FU CL, while 5-FU and5-FDHU pharmacokinetics were not related to DPD activity. Conclusion:This study shows that DPD activity in PBMNC isunrelated to 5-FU/5-FDHU disposition and patients with severe toxicitydisplay marked pharmacokinetic alterations while a reduction of DPDactivity may not occur.     

Activity of continuous-infusion 5-fluorouracil in patients with advanced colorectal cancer clinically resistant to bolus 5-fluorouracil

We have recently demonstrated that continuous-infusion (CI) 5-fluororacil (FU) eradicates human colon carcinoma cells made resistant to bolus FU in vitro. In addition, in the same experimental system, the mechanisms of resistance to pulse and CI FU were found to be different. These observations led us to test the clinical activity of a standard regimen of CI FU (300 mg/m² per day) in a cohort of 15 patients with advanced measurable colorectal cancer who were in progression after having failed to respond to bolus treatment with FU alone (3 patients) of FU combined with high-dose 6-S-leucovorin (LV) (12 patients). The median age of the patients was 68 years, and their median Eastern Cooperative Oncology Group performance status (ECOG PS) was 1. No myelotoxicity was observed. Mild diarrhea, mucositis, and vomiting occurred in 32%, 26%, and 19% of the patients, respectively, with no WHO grade 3 or 4 episodes being noted. In all, 6 of 15 patients complained of hand-foot syndrome, which was severe in 2 instances, lasting approximately 1 week. Overall, 1 partial response and 6 instances of disease stabilization, including 3 minor responses, were obtained both in patients who had been pretreated with pulse FU alone and in patients who had failed first-line treatment with FU+LV. Finally, 8 patients failed CI FU. In conclusion, these results, obtained in patients who were clearly progressing after having failed first-line treatment, support our experimental finding that resistance to bolus FU may be overcome by CI FU and extend this possibility to patients who are resistant to bolus treatment with FU+LV.This study was supported by CNR grants 92.01289. PF 70, 92.02271.PF39 and AIRC 1991. One of the authors (A. G.) is a fellow of the Associazione Italiana Ricerca Cancro     

Combined 5-fluorouracil and hydroxyurea therapy for gastrointestinal cancer.

19 patients with metastatic gastrointestinal malignancy were treated with a regimen of 5-fluorouracil (FU) 500 mg/m2 intravenously and hydroxyurea (HU) 80 MG/KG orally administered on consecutive days weekly. Antitumor responses were not observed and an unusually high incidence of neurotoxicity (21%) was noted related to dose. It is suggested that the lack of therapeutic effect and the observed toxicity may be related to the biochemical interaction of FU and HU resulting in an inability to convert FU to the active metabolite and an accumulation of catabolic products with neurotoxic effects.     

Biochemical consequences of 5-fluorouracil gastrointestinal toxicity in rats; effect of high-dose uridine

Selective protection of the normal host tissues from the toxic effects of anticancer agents would allow the use of higher, probably more effective, doses of the drugs. It has been demonstrated that delayed high-dose uridine administration after 5-fluorouracil decreases the extent of myelosuppression and causes faster regeneration of the bone marrow. We studied the biochemical consequences of the gastrointestinal toxicity caused by 5-fluorouracil and the potential of high-dose uridine treatment to influence these adverse effects. 5-Fluorouracil caused dose-related decreases in the biochemical parameters (thymidine kinase, sucrase, maltase, alkaline phosphatase) selected as early markers of the impaired metabolic activity of the intestinal mucosa. The nadir of the biochemical changes was reached between 24 h and 72 h after 5-fluorouracil treatment, and complete regeneration of the mucosa took 6–7 days. Delayed high-dose uridine administration failed to mitigate the severity of the gastrointestinal damage that ensued after 5-fluorouracil treatment, but caused significantly earlier regeneration of the mucosa.     

Chemotherapy with 5-fluorouracil and streptozotocin in carcinoid tumors of gastrointestinal origin: experiences with 13 patients.

The Authors report their experiences on the treatment of 13 consecutive cases of gastro-intestinal carcinoid tumors observed over the last 11 years. The primary sites were as follows: intestine (5 cases), appendix (3 cases), colon (1 case) and peritoneum (4 cases); only 3 patients presented systemic signs. Ten patients in advanced phase were treated with a chemotherapeutic regimen containing 5-fluorouracil (5-Fu) and streptozotocin (STZ). One case was excluded from the study because of a concomitant gastric carcinoma. Of the 9 evaluable patients, two achieved partial remission (22%) with a duration of 18+ and 66 months respectively; 4 (44.5%) had stable disease for periods ranging from 7 to 40 months and 3 cases progressed. Severe toxicity (thrombocytopenia and diarrhea) occurred in 2 cases and disappeared with the suspension of therapy. The systemic signs disappeared with treatment and did not appear in 2 cases out of 3. The prospective of the employment of new drugs such as alpha-interferon and, above all, somatostatin provides hope that this uncommon disease may have an improved response rate to treatment in the future.     

Gene polymorphisms predict toxicity to neoadjuvant therapy in patients with rectal cancer

BACKGROUND

Toxicity from neoadjuvant chemoradiation therapy (NT) increases morbidity and limits therapeutic efficacy in patients with rectal cancer. The objective of this study was to determine whether specific polymorphisms in genes associated with rectal cancer response to NT were correlated with NT‐related toxicity.

METHODS

One hundred thirty‐two patients with locally advanced rectal cancer received NT followed by surgery. All patients received 5‐fluorouracil (5‐FU) and radiation (RT), and 80 patients also received modified infusional 5‐FU, folinic acid, and oxaliplatin chemotherapy (mFOLFOX‐6). Grade ≥3 adverse events (AEs) that occurred during 5‐FU/RT and during combined 5‐FU/RT + mFOLFOX‐6 were recorded. Pretreatment biopsy specimens and normal rectal tissues were collected from all patients. DNA was extracted and screened for 22 polymorphisms in 17 genes that have been associated with response to NT. Polymorphisms were correlated with treatment‐related grade ≥3 AEs.

RESULTS

Overall, 27 of 132 patients (20%) had grade ≥3 AEs; 18 patients had a complication associated only with 5‐FU/RT, 3 patients experienced toxicity only during mFOLFOX‐6, and 6 patients had grade ≥3 AEs associated with both treatments before surgery. Polymorphisms in the genes x‐ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1), xeroderma pigmentosum group D (XPD), and tumor protein 53 (TP53) were associated with grade ≥3 AEs during NT (P < .05). Specifically, 2 polymorphisms—an arginine‐to‐glutamine substitution at codon 399 (Q399R) in XRCC1 and a lysine‐to‐glutamine substitution at codon 751 (K751Q) in XPD—were associated with increased toxicity to 5‐FU/RT (P < .05), and an arginine‐to‐proline substitution at codon 72 (R72P) in TP53 was associated with increased toxicity to mFOLFOX‐6 (P = .008).

CONCLUSIONS

Specific polymorphisms in XRCC1, XPD, and TP53 were associated with increased toxicity to NT in patients with rectal cancer. The current results indicated that polymorphism screening may help tailor treatment for patients by selecting therapies with the lowest risk of toxicity, thus increasing patient compliance. Cancer 2013. © 2012 American Cancer Society.     

Predictors of survival and toxicity in patients on adjuvant therapy with 5-fluorouracil for colorectal cancer

The present study aimed at investigating whether the simultaneous evaluation of pharmacokinetic, pharmacogenetic and demographic factors could improve prediction on toxicity and survival in colorectal cancer patients treated with adjuvant 5-fluorouracil (5FU)/leucovorin therapy. One hundred and thirty consecutive, B2 and C Duke''s stage colorectal cancer patients were prospectively enrolled. 5FU pharmacokinetics was evaluated at the first cycle. Thymidylate synthase (TYMS) 5′UTR and 3′UTR polymorphisms and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms were assessed in peripheral leukocytes. Univariate and multivariate analyses were applied to evaluate which variables could predict chemotherapy-induced toxicity, disease-free survival (DFS) and overall survival (OS). Multivariate analysis showed that: (a) low 5FU clearance was an independent predictive factor for severe toxicity (OR=7.32; P<0.0001); (b) high-5FU clearance predicted poorer DFS (HR=1.96; P=0.041) and OS (HR=3.37; P=0.011); (c) advanced age was associated with shorter DFS (HR=3.34; P=0.0008) and OS (HR=2.66; P=0.024); (d) the C/C genotype of the MTHFR C677T polymorphism was protective against grade 3–4 toxicity (P=0.040); (e) none of the TYMS polymorphisms could explain 5FU toxicity or clinical outcome.     

Low-dose cisplatin-5-fluorouracil prevents postoperative suppression of natural killer cell activity in patients with gastrointestinal cancer

BACKGROUND: The effect of administering low-dose cisplatin (CDDP)-5-fluorouracil (5-FU) postoperatively on the activity of the immune system is not known. To clarify the effect on natural killer (NK) cell activity of treatment with low-dose CDDP-5-FU, we compared NK cell activity after surgery for gastrointestinal cancer in patients treated with low-dose CDDP-5-FU, a bolus dose of mitomycin C (MMC) or no anticancer drug. METHODS: Sixty-two patients consisted of three groups: low-dose CDDP-5-FU (n = 15), MMC (n = 20) and no-drug (n = 27). Chemotherapy was initiated immediately after surgery. NK cell activity was measured on the day before surgery (pre-op) and on postoperative days 7 (POD7) and 21 (POD21). RESULTS: The NK cell activities of the CDDP-5-FU group were 37.7% at pre-op, 36.1% on POD7 and 33.6% on POD21. However, the NK cell activities in the no-drug and MMC groups were significantly decreased on POD7 (from 36.6 to 24.8% and from 31.4 to 16.6%, respectively). The NK cell activity in the MMC group remained depressed on POD21 (18.6%) whereas that in the no-drug group recovered (31.6%). CONCLUSIONS: Consecutive administration of low-dose CDDP-5-FU appears to be useful as postoperative adjuvant chemotherapy because of its preventive effect on NK cell suppression after surgery.      

Optimizing the erythromycin breath test for use in cancer patients.

The erythromycin breath test (EBT) is a putative in vivo probe for drug metabolism by cytochrome P450 3A4 (CYP3A4). Because many anticancer drugs are metabolized by this system, we sought to further develop the EBT as a tool for predicting the clearance, in cancer patients, of drugs metabolized by CYP3A4. Sixteen adult patients with incurable cancer were studied. The EBT was performed on day 1 and breath sampled after the i.v. injection of 4 microCi of 14C-erythromycin. The breath 14CO2 flux (CERt) was estimated at 11 time points over 2 h. On day 2, the EBT was repeated midway through a 10-min infusion of 100 mg of erythromycin lactobionate, and the plasma pharmacokinetics of erythromycin were determined. The infusion of 100 mg of erythromycin did not modify the EBT results significantly. The values of the conventional EBT parameter CER20 min obtained on day 1 were comparable for most subjects (0.03-0.06% dose/min), with the exception of an individual receiving the known CYP3A4 inducers dexamethasone and phenytoin who returned a value of 0.14% dose/min. There was no significant correlation between any of the conventional EBT parameters and erythromycin clearance. However, two parameters reflecting early emergence of breath radioactivity (1/TMAX and CER3 min/CERMAX) correlated significantly with erythromycin clearance (P = 0.005 and 0.006, respectively). Novel parameters derived from the EBT are significantly correlated with the clearance of erythromycin even in the presence of confounding factors, such as metastatic liver disease, altered protein binding, and comedication. These parameters may enable dose optimization of cytotoxics metabolized by CYP3A4.     

Pharmacokinetic and demographic markers of 5-fluorouracil toxicity in 181 patients on adjuvant therapy for colorectal cancer.

BACKGROUND: The relationship between 5-fluorouracil (5-FU) pharmacokinetics and toxicity following i.v. bolus administration has not been extensively studied. PATIENTS AND METHODS: One hundred and eighty-one patients on adjuvant therapy with 5-FU plus leucovorin for colorectal cancer were the study population. 5-FU pharmacokinetics was determined on day 2 of the first, third, and fifth cycles; type and the grade of adverse reactions were recorded on the next cycle. RESULTS: The 5-FU area under the curve (AUC) measured at the first cycle ranged between 146 and 1236 mg x min/l and was significantly correlated with drug dose, patients' body weight (BW) and gender, females having higher AUCs. These covariates explained only 23% of AUC variability. AUC and age were the only covariates which discriminated between toxic (grade > or =2) and nontoxic cycles (grade <2), with an optimal AUC cut-off value of 596 mg x min/l. Such a correlation was lost during the next cycles following dose reduction because of toxicity in 80 patients. CONCLUSIONS: A method for calculating the initial 5-FU dose is proposed which takes into account patient BW, gender and a target AUC of 596 mg x min/l. Nevertheless, it appears that a substantial part of 5-FU toxicity is not linked to pharmacokinetic factors and dose adjustments must still be on the basis of careful clinical surveillance.     

Predicting 5-fluorouracil toxicity in colorectal cancer patients from peripheral blood cell telomere length: a multivariate analysis

Background:

Identifying various pretreatment factors that predict chemotherapy-induced toxicity in colorectal cancer (CRC) patients undergoing treatment for their disease is crucial to optimising patient care.

Methods:

Seventy-three patients received adjuvant 5-fluorouracil (5FU)/leucovorin using either the Mayo Clinic (n=42) or a weekly schedule (n=31) and evaluated for clinical toxicity. Pretreatment blood analysis included measures of plasma uracil and dihydrouracil, peripheral blood mononuclear cell (PBMNC) telomere length (TL), standard biochemistry and cell differential analysis. On the first day of treatment 5FU-pharmacokinetic variables of area under the curve, half life and clearance were also measured. These variables together with age and gender were used in univariate and multivariate analysis as predictors of clinical toxicity.

Results:

For the Mayo schedule the primary toxicities were neutropenia (69%), mucositis (58%) and leukopenia (46%), with 70% of patients presenting with haematological toxicity ⩾grade 1 (neutropenia and/or leukopenia). Multivariate analysis showed that haematological toxicity was predicted by short TL, high platelet lymphocyte ratio (PLR) and low neutrophil count (R²=0.38, P<0.0006), whereas mucositis was predicted by age, TL and PLR (R²=0.34, P<0.001). For the weekly schedule diarrhoea predominated (16%), with female gender as the only predictive factor. Although measures of uracil metabolism correlated well with 5FU metabolism (r=0.45–0.49), they did not indicate abnormal pyrimidine metabolism in this cohort and not surprisingly failed to predict for 5FU toxicity.

Conclusion:

Short TL of PBMNC and an increased PLR were strong predictors of mucositis and haematological toxicity in CRC patients undergoing 5FU treatment in the adjuvant setting.     

Dihydropyrimidine dehydrogenase, multidrug resistance-associated protein, and thymidylate synthase gene expression levels can predict 5-fluorouracil resistance in human gastrointestinal cancer cells

Gene expression of dihydropyrimidine dehydrogenase (DPD) and newly multidrug resistance-associated protein (MRP) was found to correlate well with primary 5-FU resistance in 7 human gastrointestinal cancer cell lines. Although mRNA and protein levels of thymidylate synthase (TS) did not relate to the resistance, 5-FU treatment revealed a remarkable increase of TS expression. Such enhanced TS expression was more significant than DPD and MRP, and observed less in 5-FU sensitive cells. DPD and MRP expression levels can predict primary 5-FU resistance, and TS may be a potent predictor of cellular 5-FU resistance after 5-FU treatment.     

Development of a set of nomograms to predict acute lower gastrointestinal toxicity for prostate cancer 3D-CRT

PURPOSE: To predict acute Radiation Therapy Oncology Group (RTOG)/European Organization for Research and Treatment of Cancer (EORTC) and Subjective Objective Signs Management and Analysis/Late Effect of Normal Tissue (SOMA/LENT) toxicities of the lower gastrointestinal (LGI) syndrome in patients with prostate cancer undergoing three-dimensional conformal radiotherapy using a tool (nomogram) that takes into account clinical and dosimetric variables that proved to be significant in the Italian Association for Radiation Oncology (AIRO) Group on Prostate Cancer (AIROPROS) 0102 trial. METHODS AND MATERIALS: Acute rectal toxicity was scored in 1,132 patients by using both the RTOG/EORTC scoring system and a 10-item self-assessed questionnaire. Correlation between clinical variables/dose-volume histogram constraints and rectal toxicity was investigated by means of multivariate logistic analyses. Multivariate logistic analyses results were used to create nomograms predicting the symptoms of acute LGI syndrome. RESULTS: Mean rectal dose was a strong predictor of Grade 2-3 RTOG/EORTC acute LGI toxicity (p = 0.0004; odds ratio (OR) = 1.035), together with hemorrhoids (p = 0.02; OR = 1.51), use of anticoagulants/antiaggregants (p = 0.02; OR = 0.63), and androgen deprivation (AD) (p = 0.04; OR = 0.65). Diabetes (p = 0.34; OR = 1.28) and pelvic node irradiation (p = 0.11; OR = 1.56) were significant variables to adjust toxicity prediction. Bleeding was related to hemorrhoids (p = 0.02; OR = 173), AD (p = 0.17; OR = 0.67), and mean rectal dose (p = 0.009; OR = 1.024). Stool frequency was related to seminal vesicle irradiation (p = 0.07; OR = 6.46), AD administered for more than 3 months (p = 0.002; OR = 0.32), and the percent volume of rectum receiving more than 60 Gy (V60Gy) V60 (p = 0.02; OR = 1.02). Severe fecal incontinence depended on seminal vesicle irradiation (p = 0.14; OR = 4.5) and V70 (p = 0.033; OR = 1.029). CONCLUSIONS: To the best of our knowledge, this work presents the first set of nomograms available in the literature specific to symptoms of LGI syndrome and provides clinicians with a tailored probability of the specific outcome. Validation of the tool is in progress.     

Pharmacokinetics of levamisole in cancer patients treated with 5-fluorouracil

Purpose: To investigate the pharmacokinetics of levamisole and a metabolite, p-hydroxylevamisole in patients with colorectal cancer treated with 5-fluorouracil (5-FU). Methods: Following an intravenous bolus dose of 5-FU, 20 patients with colorectal cancer received oral doses of 50 mg levamisole every 8 h for 3 days. Immediately after the last dose, blood and urine samples were collected over at least an 8-h period. Samples were assayed for levamisole and p-hydroxylevamisole by GC/MS. The levamisole plasma and urine data were subjected to pharmacokinetic analysis using NONMEM software. Results: Substantial interpatient variability was observed in the levamisole plasma concentration-time curves. Patients with cardiovascular or gastrointestinal complications demonstrated altered absorption of levamisole. Pharmacokinetic parameter values for levamisole were similar to those obtained previously in healthy subjects and other cancer patients. Conclusions: There is no evidence that the pharmacokinetics of levamisole are altered by 5-FU administered immediately prior to levamisole administration. The relationship between the substantial intersubject variability in levamisole plasma concentration-time curves and clinical outcome following 5-FU/levamisole adjuvant chemotherapy should be examined. Received: 19 May 1999 / Accepted: 11 August 1999