l-folinic acid versus d,l-folinic acid in rescue of high-dose methotrexate therapy in children.

BACKGROUND: At this time, folinic acid (FA) is commercially available as the racemic mixture d,l-FA, whose biological activity is supported by natural l-FA. The administration of d,l-FA results in the accumulation of d-FA in plasma relative to the active l-FA form; in vitro studies have shown that d-FA can compete with the polyglutamation of methotrexate (MTX). PURPOSE: Our purpose was to compare, on a pharmacokinetic, biological, and clinical basis, the racemic mixture d,l-FA with the pure l-FA in rescue of high-dose MTX therapy (5 g/m2) in children with acute lymphocytic leukemia (ALL). METHODS: Eighteen children with ALL were entered in this trial, which was planned with a crossover design. Four cycles of MTX were administered to each patient, and rescue was achieved orally every 6 hours at a dose of 12 mg/m2 for d,l-FA and 6 mg/m2 for pure l-FA. The d,l-FA and l-FA rescues were alternated from one cycle to the next. d-FA, l-FA, and the active metabolite 5-methyltetrahydrofolate (5-MTHF) were measured in plasma using a stereospecific high-performance liquid chromatography assay. RESULTS: Considering total active folate levels (l-FA + 5-MTHF), mean residual concentrations were similar for rescue by d,l-FA and l-FA, after two and six intakes, respectively: 92 and 186 nM for d,l-FA rescue versus 100 and 184 nM for l-FA rescue. Intra-individual comparison of total active folates (l-FA + 5-MTHF) did not show any significant difference between d,l-FA rescue and l-FA rescue. After administration of d,l-FA, the accumulation of d-FA in plasma was confirmed. For both types of FA rescue, MTX terminal half-lives were identical (average value, 13.9 hours). Considering each type of toxic effect (hematologic, hepatic, renal, and digestive), there was no significant difference in the proportion of toxic cycles following l-FA rescue or d,l-FA rescue. CONCLUSION: The administration of the pure l-FA, compared with the administration of the racemic mixture, results in comparable blood profiles of active folates and MTX, leads to equivalent treatment tolerance, and avoids the plasma accumulation of d-FA.

Correlation between dihydropyrimidine dehydrogenase activity in peripheral mononuclear cells and systemic clearance of fluorouracil in cancer patients.

Dihydropyrimidine dehydrogenase (DPD) is the initial key enzyme in the catabolism of 5-fluorouracil (5-FU). We measured DPD activity in lymphocytes from 57 consecutive head and neck cancer patients while simultaneously monitoring 5-FU pharmacokinetics during 5-day, continuous infusion (1000 mg/m2/day) 5-FU therapy (82 cycles in total). The mean value for DPD activity was 0.186 +/- 0.068 (SD) nmol/min/mg of protein (range, 0.058 to 0.357). The mean value for 5-FU clearance was 2522.6 +/- 684.2 ml/min/m2 (range, 1052 to 4029). A significant linear correlation was observed between DPD activity and 5-FU clearance (r = 0.716, P less than 0.0001). DPD activity was poorly correlated to plasma uracil concentrations (r = -0.260, P = 0.0215). Likewise, plasma uracil concentrations were poorly correlated to 5-FU clearance (r = -0.214, P = 0.0595). In patients evaluated for more than one cycle (n = 18), there was large intrapatient variability in both DPD activity and 5-FU clearance. No significant difference was noted between cycles for DPD activity or 5-FU clearance (Kruskal-Wallis test). Monitoring DPD activity in lymphocytes may be useful in identifying patients at risk for altered 5-FU disposition.

Pharmacokinetics and pharmacodynamics of medroxyprogesterone acetate in advanced breast cancer patients.

PURPOSE: Medroxyprogesterone acetate (MPA) is one of the major drugs used in endocrine therapy for advanced breast cancer. However, its optimal dose still has not been clearly established. Response to treatment and drug-related side effects were analyzed as a function of plasma MPA concentrations during prolonged MPA treatment. PATIENTS AND METHODS: MPA plasma concentrations were measured (high-performance liquid chromatography [HPLC] assay) at steady state (Css min) in 129 patients (mean age, 63 years; range, 34 to 87) treated by MPA (86% were treated orally exclusively with daily doses ranging from 400 to 2,000 mg). RESULTS: A wide interpatient variability was noted in MPA Css min for the 70 patients who received 1,000 mg/d orally (median, 51 ng/mL; range, 10 to 269 ng/mL). Intrapatient analysis of the evolution of MPA Css min during prolonged treatment showed relative stability of MPA concentrations (mean CV, 20.6%). A weak but significant correlation was demonstrated between oral doses and MPA Css min (P = .016). Thirty-five percent of patients (45 of 129) developed MPA-related side effects that were associated with the highest plasma MPA concentrations; medians were 81 and 32 ng/mL for toxic and nontoxic treatments, respectively (P less than .001). Objective response was assessable in 55 patients who were treated by MPA exclusively. Plasma MPA concentrations were significantly different (P = .025) between patients with progressive disease (PD) (median, 46 ng/mL) and those with complete response (CR), partial response (PR), or stable disease (SD) (median 65 ng/mL). Comparison of CR plus PR versus SD versus PD showed only a tendency toward significant differences in MPA Css min (P = .07). Analysis of toxicity and response as a function of the oral dose did not show any significant relationship. These data suggested an optimal therapeutic window for MPA Css min located within 50 to 70 ng/mL. CONCLUSION: This study demonstrates that plasma MPA concentration, as opposed to the administered dose, is a determining factor for toxicity and response therapy [corrected].

Relationship between fluorouracil systemic exposure and tumor response and patient survival.

PURPOSE: The aim of this study was to analyze the link between fluorouracil (FU) systemic exposure and tumor response and overall survival. PATIENTS AND METHODS: One hundred eighty-six patients (162 men, 24 women) with head and neck cancer were studied. All received cisplatin plus FU for three cycles as first-line chemotherapy. The treatment consisted of cisplatin (100 mg/m2 intravenously [IV]) followed by a 5-day continuous venous infusion of FU (1 g/m2/d). The median follow-up duration for the 104 patients alive was 24 months. For each cycle, we calculated the area under the curve over the duration of pharmacokinetic follow-up (AUC0-105 h) for plasma FU. For each patient, we analyzed the averaged AUC0-105 h and the averaged total dose for the three cycles. RESULTS: The response rate was 30% complete responses (CRs), 22% partial responses (PRs) more than 75%, 25% PRs less than 75%, and 23% no response (NR). Medians for averaged AUC and dose per cycle were 27,906 ng/mL h (first through third quartile, 25,398 to 31,060) and 7,000 mg (first through third quartile, 6,200 to 7,833), respectively. The tumor response was significantly linked to tumor stage (P < .001) and to averaged AUC (P = .05), but not to averaged dose. Analysis of parameters (continuous variable) expressing FU treatment intensity showed that dose did not influence survival contrary to the AUC (P = .001). The AUC remains significant (P = .025) in a multivariate analysis including tumor stage, demonstrating that the greater the FU systemic exposure, the longer the survival. CONCLUSION: These results strengthen the interest of individual FU dose adaptation based on pharmacokinetics.

Tumoral-reduced folates and clinical resistance to fluorouracil-based treatment in head and neck cancer patients.

PURPOSE: To describe the distribution of tumoral-reduced folates in cancer patients and to analyze the link between this parameter and antitumor efficacy of fluorouracil (FU)-based induction chemotherapy. PATIENTS AND METHODS: Ninety-five patients with head and neck squamous cell carcinoma were included in the present study and 41 received induction treatment with FU-based chemotherapy (35 men and six women; mean age, 59 years; range, 40 to 76). Thymidylate synthase (TS) activity was measured according to the tritium-release assay. Reduced folates (5-10 methylenetetrahydrofolate [CH2FH4] plus tetrahydrofolate) were measured according to the entrapment assay. RESULTS: Among the whole group of patients, reduced folates ranged from nondetectable (< 0.3) to 17.7 pmol/mg protein; CH2FH4 ranged from nondetectable (< 0.3) to 8.2 pmol/mg protein. There was no significant link between tumoral levels of reduced folates and the severity of disease stage. Among 41 treated patients, there were 12 (29%) complete responses (CRs), 18 (44%) partial responses (PRs), and 11 patients (27%) with no response (NR). No statistically significant relationship was observable between TS activity and response. The distribution of CH2FH4 in tumors was significantly higher for complete responders in comparison to patients with a PR or NR. CONCLUSION: The present clinical data demonstrate the importance of basal tumoral-reduced folates for the achievement of optimal efficacy of FU-based treatment. They may have implications for the identification of patients resistant to FU chemotherapy and for a better understanding and management of FU modulation by folinic acid (FA).

Phase II trial of cisplatin, fluorouracil, and pure folinic acid for locally advanced head and neck cancer: a pharmacokinetic and clinical survey.

PURPOSE: To analyze clinical and pharmacokinetic data of cisplatin (CP)/fluorouracil (FU)/l folinic acid (l FA) chemotherapy administered as first-line treatment to locally advanced head and neck cancer patients. PATIENTS AND METHODS: Thirty-nine patients (35 men and four women; median age, 60 years; six stage III and 33 stage IV) received CP on day 1 (100 mg/m2) followed by l FA (200 mg/m2/d x 5) plus FU (500 mg/m2/d x 5) administered by continuous venous infusion (three cycles planned). Mean plasma concentrations of FU, l FA, and 5-methyltetrahydrofolate (5MTHF) over the cycle were computed. RESULTS: Clinical response was assessable for 33 patients. Response rates on the primary tumor site (n = 33) were 63.7% complete responses (CRs), 24.2% partial responses (PRs), and 12.1% treatment failures. Response rates on lymph nodes (n = 27) were 40.7% CRs, 37.1% PRs, and 22.2% treatment failures. The most frequent toxicity was mucositis (36.2% of cycles grade 3 to 4). Grade 3 to 4 nausea-vomiting, diarrhea, neutropenia, and thrombocytopenia occurred in 6.7%, 1.9%, 13.3%, and 1% of cycles, respectively. Pharmacokinetic analysis showed a wide interpatient variability for both FU (mean, 1.01 mumol/L; range, 0.16 to 2.09), l FA (mean, 1.89, mumol/L; range, 0.52 to 7.88) and 5MTHF plasma concentrations (mean, 3.85 mumol/L; range, 1.30 to 8.11). A significant correlation was demonstrated between FU concentration and hematologic toxicity grade, mucositis grade, and nausea-vomiting/diarrhea grade. Regarding tumor response, patients who failed to respond significantly exhibited lower FU and total folate concentrations than patients with a CR or PR. CONCLUSION: This study highlights the efficacy of CP/FU/l FA in head and neck carcinoma and establishes the clinical importance of coupled FU/FA pharmacokinetics to predict pharmacodynamic variability.

Response to fluorouracil therapy in cancer patients: the role of tumoral dihydropyrimidine dehydrogenase activity.

PURPOSE: The aim of the present study was to analyze the role of thymidylate synthase (TS; main cellular target of fluorouracil [FU]) and dihydropyrimidine dehydrogenase (DPD; rate-limiting enzyme of FU catabolism) in tumoral biopsies with respect to FU responsiveness. PATIENTS AND METHODS: This prospective study was conducted on 62 head and neck cancer patients (six stage II, 16 stage III, and 40 stage IV). All received first-line chemotherapy with biomodulated FU (5-day continuous infusion). Before treatment, a tumor biopsy and control biopsy (symmetrical nontumoral area) were obtained. Cytosolic TS and DPD activities were measured using radioenzymatic assays. RESULTS: DPD activity was detectable in all samples, without a significant difference between tumoral (median, 60 pmol/min/mg protein; range, 13 to 193) and nontumoral samples (median, 68 pmol/min/mg protein; range, 12 to 150). Tumoral TS and tumoral DPD were not significantly influenced by tumor localization or tumor staging. Among 52 tumors assessable for clinical response, we observed 46% complete responses (CRs), 33% partial responses (PRs), and 21% no responses (NRs). No relationship was demonstrated between TS activity and response to FU therapy. The comparison of tumoral DPD between complete responders and partial or nonresponders showed a trend toward significance (P = .06). In an attempt to reduce variability, we analyzed the tumoral/nontumoral DPD activity ratio; complete responders exhibited a significantly lower normalized DPD than partial or nonresponding patients (median, 0.86, 1.18, and 1.42 for CR, PR, and NR, respectively; CR v PR plus NR, P = .03). CONCLUSION: Although resistance to FU is multifactorial, the present clinical study suggests that FU catabolism in target cells is probably a determinant factor for FU responsiveness in cancer patients and justifies the clinical use of specific DPD inhibitors as FU biomodulators.

Population study of dihydropyrimidine dehydrogenase in cancer patients.

PURPOSE: We conducted a prospective study on a large set of cancer patients in an attempt to evaluate the incidence of complete or partial dihydropyrimidine dehydrogenase (DPD) deficiency as found in peripheral mononuclear cells (PMNC). PATIENTS AND METHODS: One hundred eighty-five unselected consecutive cancer patients were included. The population consisted of 152 men (mean age, 62.1 years; range, 35 to 90) and 33 women (mean age, 59.2 years; range, 36 to 77). Sixty-eight were head and neck patients treated by a 5-day continuous infusion of fluorouracil (FU; starting dose, 1 g/m2/d, with dose adaptation based on pharmacokinetics) for which DPD activity was measured 2 to 3 days before FU administration (94 cycles analyzed). PMNC-DPD activity was measured by a radio-enzymatic assay using carbon-14-FU. RESULTS: DPD activity in the entire population showed a unimodal distribution, which globally fits a gaussian distribution. Mean and median DPD activity values were 0.222 and 0.211 nmol/min/mg protein, respectively (range, 0.065 to 0.559). No total DPD deficiency was found. Multifactor analysis of variance showed that liver function (biologic evaluation) and age did not influence DPD activity, but that DPD activity was, on average, 15% lower in women (0.194 nmol/min/mg protein) than in men (0.228 nmol/min/mg protein) (P = .03). No difference was demonstrated between premenopausal and postmenopausal women. In patients treated with FU, the risk of developing side effects was not linked to pretreatment DPD activity. FU-related toxicity was linked to FU systemic exposure. The correlation between pretreatment DPD activity and FU systemic clearance (CI) was weak (n = 90, linear regression r = .31, P = .002). Pretreatment DPD activity in patients who required a dose reduction was not significantly different from DPD activity in patients who did not require dose modification. CONCLUSION: From the present study, it appears that total DPD deficiency is a rare event. Although pretreatment DPD activity cannot be a useful indicator for improving FU dose adaptation strategy, the identification of severe DPD deficiency (< 0.100 nmol/min/mg protein) could lead to starting the treatment with a markedly reduced FU dose or even to using an alternative chemotherapy regimen.

Influence of sex and age on fluorouracil clearance.

PURPOSE: Currently, fluorouracil (5-FU) is one of the major drugs used in cancer chemotherapy. Several investigators, including ourselves, have demonstrated a link between abnormalities in 5-FU clearance (Cl) and the risk of developing more or less 5-FU-related toxicities. Age and sex are among the host factors that have been implicated in the pharmacokinetic variability of drugs. Presently, no data are available on the possible influence of sex and age on 5-FU Cl. PATIENTS AND METHODS: Three hundred eighty patients (mean age, 61.7 years; range, 25 to 91; 301 men and 79 women) with squamous cell carcinoma (sre) of the head and neck were treated in our institution between 1987 and 1991. 5-FU Cl was determined for a total of 1,092 chemotherapy cycles. Each cycle consisted of cisplatin and 5-day continuous intravenous infusion 5-FU (daily doses ranging between 365 and 1,224 mg/m2). RESULTS: 5-FU Cl values (L/h/m2) showed a wide dispersion for both men (median, 179; range, 29 to 739) and women (median, 155; range, 56 to 466). 5-FU Cl values were lower significantly for women compared with men (P = .0005). When adjusted for age and dose, the influence of sex on log Cl remained significant (P = .013). There was no evidence that age modified 5-FU Cl when adjusted for sex and dose. Interestingly, for both men and women, the oldest patients (greater than 70 years) maintained their ability to clear 5-FU with daily doses that ranged from 500 to 1,000 mg/m2. CONCLUSIONS: These data indicate that the capacities to clear 5-FU are lower in women compared with men and are not influenced by age. It would be of interest to know whether this sex-related difference in 5-FU Cl may be clinically relevant by considering both toxicity and tumor response to 5-FU treatment.

Search for the optimal schedule for the oxaliplatin/5-fluorouracil association modulated or not by folinic acid: preclinical data.

The combination of oxaliplatin (LOHP)-5-fluorouracil (FU)-folinic acid (FA) has provided high response rates in pretreated patients with advanced colorectal cancer that is resistant to FU-FA. However, the choice of the optimal schedule between LOHP, FU, and FA remains open. The purpose of the present study was to compare, at equivalent drug area under the curve, different schedules for the LOHP-FU +/- FA combinations on four human colorectal cancer cell lines. FU +/- FA was tested as a 2-h short exposure ("bolus"), a 118-h continuous exposure ("infusion"), or a 22-h mixed exposure ("De Gramont protocol"). LOHP was administered for 2 h before, during, or after FU +/- FA exposure. Isobologram analyses revealed that LOHP associated with FU +/- FA resulted in synergistic cytotoxic effects whatever the tested schedules (in > or = 75% of cases). For the FU-LOHP combination, cytotoxicity was significantly different according to the FU exposure type (short > mixed > continuous) and was independent of the LOHP position. In contrast, for the FU-FA-LOHP combination, neither the FU exposure type nor the LOHP position significantly influenced cytotoxicity. The presence of FA significantly enhanced the cytotoxicity of FU-LOHP (P < 0.001); this potentiation was independent of the FU exposure type and was significantly influenced by the LOHP position (LOHP after FU-FA > LOHP during FU-FA > LOHP before FU-FA). In conclusion, in contrast with the recognized superiority of continuous FU exposure over short exposure when the drug is given alone, the FU-LOHP combination is more cytotoxic when FU is given as a short exposure. This suggests the potential interest of such a schedule in the clinical setting.

Link between dihydropyrimidine dehydrogenase activity in peripheral blood mononuclear cells and liver.

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluorouracil (FU) catabolism, which occurs mainly in the liver. Several cases of severe FU-related toxicity have been reported in patients exhibiting a marked DPD deficiency measured in peripheral blood mononuclear cells (PBMCs). In addition, it has been shown that PBMC-DPD activity correlates to systemic FU clearance. The purpose of the present study was to closely evaluate the link between DPD activity measured in PBMCs and in liver samples obtained from the same patients. This prospective study was conducted on 27 patients (18 men and 9 women) who underwent laparotomy for various pathologies. Liver biopsies were performed in normal liver and immediately stored in liquid nitrogen. Biological liver function tests were within normal values for all patients. Concomitantly to the liver biopsy, a blood sample was taken and PBMCs were immediately isolated and stored at -80 degreesC. Liver-DPD and PBMC-DPD activities were measured by a radioenzymatic assay using 14C-FU as substrate (sensitivity limit, 5 pmol/min/mg protein; interassay reproducibility, 10%). Liver-DPD (mean, 178; median, 186; range, 54-290 pmol/min/mg protein) and PBMC-DPD (mean, 196; median, 205; range, 80-275 pmol/min/mg protein) exhibited the same pattern of distribution. Neither liver-DPD nor PBMC-DPD was significantly different between men and women. A significant linear correlation was demonstrated between liver- and PBMC-DPD activity (liver-DPD = 0.6 x PBMC-DPD + 59, r = 0.56, P = 0.002). Interestingly, the patient who exhibited the lowest PBMC-DPD activity (80 pmol/min/mg protein, at risk value for developing FU-related side effects) also had very low liver-DPD activity (98 pmol/min/mg protein). In conclusion, in patients with normal liver function, DPD activity measured in PBMCs reflects DPD activity expressed in the liver. The demonstrated link between liver- and PBMC-DPD activity reinforces the interest in DPD investigation in PBMCs for selecting, before FU-containing chemotherapy, patients at risk of developing severe toxicities due to impairment of FU clearance.

Dihydropyrimidine dehydrogenase: a tumoral target for fluorouracil modulation.

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluorouracil (FU) catabolism. Ethynyluracil (776C) is a very potent, mechanism-based irreversible DPD inhibitor that improves the antitumor efficacy and the therapeutic index of FU in laboratory animals. We tested the cytotoxic effects of the FU-776C combination on a panel of 12 human cancer cell lines (4 breast, 4 head and neck, 3 colon, and 1 duodenum). Basal DPD activity (radioenzymatic assay) and FU sensitivity [FU 50% inhibitory concentration (IC50), 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test] were determined. The FU potentiation by 776C was calculated from the ratio (F) of FU IC50 without 776C divided by FU IC50 with 776C. 776C was not cytotoxic to any of the cell lines tested. On CAL51 cell line expressing a high basal DPD activity, FU enhancement by 776C was a saturable phenomenon related to the 776C concentration; the inhibition of DPD increased between 10(-12) to 10(-6) M of 776C. For the following studies, 776C was tested at 10(-6) M. FU IC50 varied from 15 to 7770 microM among cell lines (median, 390 microM). Basal DPD activity ranged from not detectable (< pmol/min/mg protein) to 320 pmol/min/mg protein among cell lines (median, 53 pmol/min/mg protein). For the 12 cell lines tested, the mean F ranged from 0.7 (no enhancement of FU cytotoxicity by 776C) up to 5.2 and was significantly related to the basal DPD activity: the greater the DPD activity, the greater the FU enhancement factor (Spearman rank correlation, P = 0.019). Enhancement of FU cytotoxicity by 776C occurred only in the six cell lines expressing the greatest basal DPD activity (>50 pmol/min/mg protein, F ranging between 1.7 and 5. 2), whereas 776C did not modify FU cytotoxicity in the remaining cell lines expressing the lowest DPD activity (<50 pmol/min/mg protein, F ranging between 0.7 and 1.4). F was significantly different between these two groups of cell lines (P = 0.005). These results point out that DPD is an interesting target for FU pharmacomodulation.

Clinical impact of pharmacokinetically-guided dose adaptation of 5-fluorouracil: results from a multicentric randomized trial in patients with locally advanced head and neck carcinomas.

A significant link between 5-fluorouracil (5FU) plasma concentration and its therapeutic activity has been demonstrated in colon and head and neck cancer patients for 5FU used as a continuous infusion. Dose adjustment based on pharmacokinetic follow-up has been proposed to decrease hematological and digestive toxicities, but the clinical impact of this approach has not yet been demonstrated. A randomized multicentric study was conducted to evaluate the clinical interest of 5FU dose adaptation guided by pharmacokinetics. One hundred twenty-two head and neck cancer patients were randomly assigned to receive induction chemotherapy with cisplatin (100 mg/m2, day 1) and 5FU (96-h continuous infusion), either at standard dose (St-arm; 4 g/m2) or at a dose adjusted according to the 5FU area under the curve (AUC0-48h; PK-arm). In total, 106 patients were evaluable for toxicity and response. In the PK-arm (n = 49), 5FU doses and area under the curve were significantly reduced during cycle 2 and cycle 3 (P < 0.001) as compared with the St-arm (n = 57). Grade 3-4 neutropenia and thrombopenia were significantly more frequent in the St-arm as compared with the PK-arm (17.5% versus 7.6%, respectively; P = 0.013). No grade 3-4 mucositis occurred in the PK-arm, whereas 5.1% was observed in the St-arm (P < 0.01). The objective response rate was comparable in the two treatment arms: 77.2% in the St-arm versus 81.7% in the PK-arm. The present study is the first to demonstrate, in a randomized design, the clinical interest of an individual 5FU dose adaptation based on pharmacokinetic survey, in terms of therapeutic index improvement.

Epidermal growth factor receptor and labeling index are independent prognostic factors in glial tumor outcome.

The aim of this study was to perform a multivariate analysis including clinical and biological prognostic factors on glial tumor outcome. Seventy-nine patients were analyzed (48 men and 31 women; mean age = 56 years, range = 16-77 years): 7 had a benign glial tumor (grades 1 and 2), 21 had an anaplastic glial tumor (grade 3), and 51 had a glioblastoma (grade 4). Median follow-up was 17.9 months for patients who survived (50 patients died). Biopsies were obtained at time of diagnosis (complete tumor resection in 62 patients and stereotaxic biopsies in 17 patients). Epidermal growth factor receptor (EGFR) was measured by a binding assay, and labeling index (LI) was measured by tritiated thymidine incorporation. EGFR varied from 4 to 73,110 fmol/mg protein (mean = 3912 fmol/mg protein; median = 374 fmol/mg protein; n = 79). LI varied between 0.1 and 16.5% (mean = 6.2%; median = 5.2%; n = 40). Log10 EGFR was significantly and positively correlated with patient age. LI was significantly different according to tumor histology. Univariate Cox analysis (end point was cancer death) showed that age (P = 0.027), log10 EGFR (P = 0.025), and LI (P = 0.0019) were significant continuous variables, the survival being shortened when the covariable increased; tumor resection (P = 0.015, relative risk = 0.45) and histology (P = 0.0009) were significant categorical factors. A multivariate Cox analysis (forward selection) including age, histology, tumor resection, log10 EGFR, and LI revealed that log10 EGFR, LI, and tumor resection were the only independent significant predictors of survival. This multivariate approach reveals that the clinical prognostic factors of glial tumors, namely age and tumor histology, disappear, to the benefit of intrinsic characteristics of the tumor, i.e., EGFR expression and LI, suggesting that coupled EGFR and LI determination could be a useful tool for better evaluation of glial tumor outcome.

Decreased folylpolyglutamate synthetase activity in tumors resistant to fluorouracil-folinic acid treatment: clinical data.

Thymidylate synthase (TS) is the main target for fluorouracil (FU). Optimal cellular concentrations of reduced folates in polyglutamated forms [via folylpolyglutamate synthetase (FPGS)] are necessary for achieving maximal TS inhibition. The aim of this multicentric prospective study was to analyze the link between clinical response to FU therapy for liver metastases of colorectal carcinoma and tumoral TS and FPGS activities. Forty-four advanced colorectal cancer patients (15 women and 29 men; median age 63, range, 27-78 years) receiving a standard FU-folinic acid protocol were included. A single hepatic tumoral biopsy was obtained systematically at the time of diagnosis. For 24 patients, a biopsy in the primary colon tumor was available. TS and FPGS activities were measured by radioenzymatic assays. Clinical response on hepatic metastases was 1 complete response, 12 partial responses, 14 stabilizations, and 17 progressions. In hepatic biopsies, TS activity (median, 185; range, <10-3111 fmol/min/mg protein) and FPGS activity (median, 1270; range, <400-3730 fmol/min/mg protein) exhibited a wide variability. TS activity in primary tumors (median, 461; range, 35-2565 fmol/min/mg protein) was significantly higher than in hepatic metastases. No difference was observed between primaries and metastases for FPGS. FPGS activity expressed in liver metastases was significantly correlated to that expressed in primaries. The distribution of TS activity in liver metastases was not significantly different between responsive and nonresponsive patients. However, FPGS activity measured in liver metastases was significantly higher in responsive patients (median, 1550 fmol/min/mg protein) than in nonresponsive patients (median, 1100 fmol/min/mg protein). A discriminant analysis revealed that 24 of the 25 patients exhibiting a liver FPGS activity 320 fmol/min/mg protein were nonresponding patients. These data establish for the first time the potential importance of tumoral FPGS activity for assessing FU-folinic acid responsiveness in the clinical setting.

Known variant DPYD alleles do not explain DPD deficiency in cancer patients.

Dihydropyrimidine dehydrogenase (DPD) degrades over 80% of administered 5-fluorouracil (5FU), thereby regulating the efficacy of this commonly used anticancer agent. DPD activity is highly variable (8-21-fold) and individuals with reduced activity have a high risk of 5FU toxicity. DPYD encodes DPD protein and 13 different mutations have been reported in DPD-deficient subjects. However, the contribution of these variant genotypes to polymorphic DPD activity in vivo is not clear. The previously described DPYD mutations are contained in 10 exons. These 10 exons were sequenced in a cohort of cancer patients with reduced (n = 23) or normal (n = 14) DPD activity to determine the contribution of each variant allele to low DPD activity in vivo. Eight of the 13 previously defined DPYD mutations (G62A, delta TCAT295-298, C703T, G1003T, G1156T, delta C1897, G2657A, and G2983T) were not detected. A previously defined exon 13 mutation (G1601A) was detected in three individuals with reduced DPD activity. An exon 14 splice donor site mutation (intron14 G1A) was detected in a normal DPD activity individual. It was demonstrated that T85C, A1627G and G2194A are common polymorphisms. A novel exonic mutation (T1679G) was detected in a patient with reduced DPD activity and 5FU toxicity. In addition, three novel common polymorphisms were detected in introns 10 and 13. Only three patients did not have any mutations and 30 had multiple DPYD mutations in the regions examined. However, only 17% (4/23) of the patients with a low DPD phenotype have a molecular basis for reduced activity. Although novel DPYD variants have been identified in this study, the 17 DPYD mutations now described do not entirely explain polymorphic DPD activity and toxic response to 5FU. These data emphasize the complex nature of the molecular mechanisms controlling polymorphic DPD activity in vivo.

Spontaneous or imposed circadian changes in plasma concentrations of 5-fluorouracil coadministered with folinic acid and oxaliplatin: relationship with mucosal toxicity in patients with cancer.

Pharmacokinetics of total platinum, 5-fluorouracil, l-folinic and d-folinic acid, and 5-methyltetrahydrofolate were studied in plasma from nine patients with advanced colorectal cancer treated with oxaliplatin (20 mg/m2/day), 5-fluorouracil (600 mg/m2/day), and folinic acid (300 mg/m2/day). Drugs were administered with a programmable-in-time pump by continuous infusion for 5 days. We compared two drug delivery schedules: constant rate versus chronomodulated rate with peak of oxaliplatin at 4 pm and peak of 5-fluorouracil and folinic acid at 4 am. In the chronomodulated schedule, plasma concentrations of the drugs paralleled the pump functioning: maximum platinum concentration near 4 pm, and maximum 5-fluorouracil and folate concentrations near 4 am. When drugs were administered at a constant rate, mean plasma concentration of 5-fluorouracil varied in a circadian manner each treatment day, that is, a peak at 4 am (approximately 800 ng/ml) and a trough at 1 pm (approximately 100 ng/ml). Mean plasma levels of total platinum and folate compounds increased over the first 24 hours. Total platinum mean level and that of the inactive d-folinic acid isomer reached a constant plasma concentration, whereas biologically active folates exhibited circadian variation in their plasma concentrations (peak around 7 am, trough near 6 pm, and amplitude approximately 10%). Severe mucositis was exhibited by all four patients on the flat schedule, but only by one on the chronomodulated schedule (p < 0.008). Individual pharmacokinetic and toxicity data showed that patients with circadian rhythms in 5-fluorouracil concentrations were least sensitive to 5-fluorouracil-related toxicity. Thus amplification or induction of such rhythm in 5-fluorouracil exposure may permit dose escalation.

Age-related difference in tamoxifen disposition.

PURPOSE: To investigate the pharmacokinetic aspects of tamoxifen, such as the pharmacokinetic-pharmacodynamic (toxicity and clinical response) relationship and the influence of hepatic dysfunction, age, treatment duration, and associated chemotherapy on tamoxifen pharmacokinetics. PATIENTS AND METHODS: Three hundred sixteen patients with breast cancer (247 postmenopausal women) were investigated. Mean age was 58 years (age range, 29 to 85 years). One hundred seventeen patients received tamoxifen as single therapy (adjuvant, 60; neoadjuvant, 17; metastatic, 40); 292 of 316 received 30 mg daily. We obtained 794 blood samples at steady state. Tamoxifen and metabolites, N-desmethyltamoxifen, N-desdimethyltamoxifen, primary alcohol, and 4-hydroxytamoxifen were measured by HPLC. RESULTS: Serum concentrations of tamoxifen and metabolites showed a wide asymmetrical distribution. Median and extremes were 347 nmol/L (not detectable [ND] to 1677) for tamoxifen, 572 nmol/L (ND to 3132) for N-desmethyltamoxifen, 109 nmol/L (ND to 795) for N-desdimethyltamoxifen, and 59 nmol/L (ND to 390) for primary alcohol. 4-Hydroxytamoxifen was detectable in 9.5% of the samples (ND to 162 nmol/L). Neither the absolute nor the relative concentrations of each compound showed significant variations during treatment. Chemotherapy concomitant with tamoxifen slightly increased the tamoxifen blood concentration. Hepatic dysfunction had no obvious effect on drug concentrations, an exception being a slight reduction in the relative proportion of tamoxifen. The influence of age revealed that concentrations of tamoxifen and metabolites increased significantly with age: women younger than 40 years had a tamoxifen plus metabolite median concentration of 802 nmol/L compared with 2428 nmol/L for women older than 80 years. In the 28 patients in whom tamoxifen-related side effects developed, the proportion of demethylated metabolites was higher than that in patients in whom toxicity did not develop. There was no difference in drug concentrations between responding and nonresponding patients. CONCLUSION: Despite the tremendous interpatient variability in drug concentrations, the present data show that tamoxifen and metabolite concentrations significantly increase with age.

Epidermal growth factor receptor expression and suramin cytotoxicity in vitro.

Twenty-five cell lines derived from nine different human cancers were tested for the cytotoxic activity of suramin. Two different initial cellular concentrations were used: C1 (800-2000 cells per well) and C2 (3000-7000 cells per well). Suramin concentrations ranged from 50 to 2500 micrograms/ml. Cytotoxicity was assessed by the MTT test. Epidermal growth factor receptors (EGFR) were assayed by competition analysis and Scatchard plots. In sixteen cell lines suramin had an unexpected growth stimulation effect at low concentration (50-125 micrograms/ml). IC50 varied from 21 micrograms/ml (osteosarcoma, OS2) to 1408 micrograms/ml (melanoma, CAL 24) and, within melanoma cell lines, it varied from 120 micrograms/ml (CAL 41) to 1408 micrograms/ml (CAL 24). The individual IC50 values were positively and significantly linked with the initial cellular density. Eighteen cell lines had measurable EGFR (six with two families of sites, twelve with one): Kd varied between 0.004 nmol/l for the highest affinity site (melanoma, CAL 7) to 1.852 nmol/l for the lowest affinity site (lung, CAL 12). There was no relation between presence or absence of EGF binding sites and distribution of IC50, but for cells with measurable EGFR there was a weak but significant correlation between the number of EGF binding sites per cell and the corresponding IC50 (r = -0.53, P = 0.021).

Long-term stability of 5-fluorouracil and folinic acid admixtures.

5-Fluorouracil (5-FU) and d,1-folinic acid (FA) are used in association to treat a wide variety of malignancies. The stability and the compatibility of 5-FU and FA in combination in intravenous admixtures were studied under various storage conditions and with drug concentrations matching their clinical use (0.9% sodium chloride, 5% dextrose, protected from light or not). 5-FU and FA concentrations (mg/ml) were 6.5 or 50 and 4.0 or 30.8, respectively. Successive aliquots of the drugs mixtures were withdrawn during 60 h from 500 ml glass bottles and 500 ml polyvinyl chloride (PVC) bags (at room temperature) and during 120 h from cassettes (at 32 degrees C). Drug concentrations were measured by high performance liquid chromatography. For all conditions tested, the changes in 5-FU and FA relative to the initial concentrations remained within the assay reproducibility (10%). In complement, infrared Fourier transformation spectrophotometry has not shown a significant fixation of FA or 5-FU on the PVC bags, in all tested conditions. Under the conditions examined above 5-FU and FA can be mixed in the same container for their use in cancer chemotherapy. This can have practical consequences by simplifying the widely used treatment protocols associating 5-FU and FA.