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Randomised trial of irinotecan versus fluorouracil by continuous infusion after fluorouracil failure in patients with metastatic colorectal cancer.

BACKGROUND: In phase II trials, irinotecan is active in patients with advanced colorectal cancer, but the survival and clinical benefit of irinotecan compared with second-line fluorouracil by continuous infusion is not known. METHODS: 267 patients who had failed to respond to first-line fluorouracil, or whose disease had progressed after treatment with first-line fluorouracil were randomly allocated irinotecan 300-350 mg/m2 infused once every 3 weeks or fluorouracil by continuous infusion. Treatment was given until disease progression, unacceptable toxic effects, or the patient refused to continue treatment. The primary endpoint was survival, while progression-free survival, response rate, symptom-free survival, adverse events, and quality of life (QoL) were secondary endpoints. FINDINGS: 133 patients were randomly allocated irinotecan and 134 were allocated fluorouracil by continuous infusion. Patients treated with irinotecan lived for significantly longer than patients on fluorouracil (p=0.035). Survival at 1 year was increased from 32% in the fluorouracil group to 45% in the irinotecan group. Median survival was 10.8 months in the irinotecan group and 8.5 months in the fluorouracil group. Median progression-free survival was longer with irinotecan (4.2 vs 2.9 months for irinotecan vs fluorouracil, respectively; p=0.030). The median pain-free survival was 10.3 months and 8.5 months (p=0.06) for irinotecan and fluorouracil, respectively. Both treatments were equally well tolerated. QoL was similar in both groups. INTERPRETATION: Compared with fluorouracil by continuous infusion second-line irinotecan significantly improved survival in patients with advanced colorectal cancer.

Adenocarcinoma↗

Antitumor activity of alkylesters of 1-beta-D-ribofuranosyl-5-fluorouracil-5'-phosphate against murine lymphoma L5178Y resistant to 1-beta-D-ribofuranosyl-5-fluorouracil.

A 1-beta-D-ribofuranosyl-5-fluorouracil-resistant clone, designated L5178Y/FUR, was established in this experiment. This is one of the colonies derived from a subculture which acquired resistance to 1-beta-D-ribofuranosyl-5-fluorouracil by passaging the L5178Y cells through four sucessive episodes of culture in Fischers' medium containing 1-beta-D-ribofuranosyl-5-fluorouracil; each analog treatment was followed by recovery intervals. In this subline, IC99 values for 1-beta-D-ribofuranosyl-5-fluorouracil was 0.57 muM, which was 24 times as great as in the parent line (0.0024 muM), and this subline showed a cross resistance to 5-fluorouracil. New alkylesters of 1-beta-D-ribofuranosyl-5-fluorouracil 5'-phosphate (FUMP-alkylesters) were synthesized and their antitumor activity was examined against 1-beta-D-5-fluorouracil-sensitive and -resistant L5178Y sublines. Only hexadecylester of 1-beta-D-ribofuranosyl-5-fluorouracil 5'-phosphate was effective, not only to 1-beta-D-ribofuranosyl-5-fluorouracil line but also to 1-beta-D-ribofuranolsyl-5-fluorouracil-resistant subline. Other compounds showed cross resistant in the 1-beta-D-ribofuranosyl-5-fluorouracil-resistant cells.

Animals↗

Biochemical modulation of 5-fluorouracil: a randomized comparison of sequential methotrexate, 5-fluorouracil and leucovorin versus sequential 5-fluorouracil and leucovorin in patients with advanced symptomatic colorectal cancer. The Nordic Gastrointestinal Tumor Adjuvant Therapy Group.

BACKGROUND: The optimal chemotherapy for advanced colorectal carcinoma is not known. Two regimens, both based upon biochemical modulation of 5-FU, were compared in a randomized multicenter trial. PATIENTS AND METHODS: A total of 202 symptomatic patients were randomly allocated to receive either sequential methotrexate, 250 mg/m2, during the first 2 hours and 5-FU, 500 mg/m2, at hours 3 and 23 followed by leucovorin rescue initiated at hour 24 (15 mg x 8) (MFL) or sequential 5-FU 500 mg/m2 followed by leucovorin 60 mg/m2 30-40 minutes later, on days 1 and 2 (FLv). Treatments were repeated every 14 days for eight courses and then every 3 to 4 weeks. Four patients were unevaluable. RESULTS: The two treatments were equally effective with respect to objective response rates (complete (CR)+partial (PR), MFL 17%, FLv 21%), subjective response rates (symptom relief in the absence of severe adverse effects, 45% vs. 37%), and survival (median 7.5 vs. 9 months). All responses lasted at least 4 months. Overall, toxicity was low and comparable between the groups, but serious toxicity was more common in the MFL group. CONCLUSIONS: Since FLv is easier to administer and carries less risk for serious toxicity, it should be recommended as a first-line treatment before MFL. On either regimen, about 40% of symptomatic patients can expect palliation, i.e., symptomatic relief without severe adverse effects, for at least 4 months.

Adult↗

A phase II evaluation of a 3-drug combination of cyclophosphamide, doxorubicin and 5-fluorouracil and of 5-fluorouracil in patients with advanced bladder carcinoma or stage D prostatic carcinoma.

The Southeastern Cancer Study Group has evaluated 5-fluorouracil administered intravenously weekly at a dosage of 600 mg. per M.2 as a single agent, and the 3-drug combination of cyclophosphamide, doxorubicin and 5-fluorouracil in patients with metastatic carcinoma of the bladder and of the prostate previously untreated with cytotoxic chemotherapy in a prospectively randomized phase II study. In 4 of 18 patients with bladder carcinoma 5-fluorouracil induced an objective response, and cyclophosphamide, doxorubicin and 5-fluorouracil induced an objective response in 3 of 21 patients. In patients with prostatic carcinoma 5-fluorouracil induced an objective response as measured by a 50 per cent decrease in prostatic acid phosphatase determined in a central reference laboratory in 3 of 25 patients and objective stability by National Prostatic Cancer Project criteria in 14 of 29 patients. Cyclophosphamide, doxorubicin and 5-fluorouracil induced an objective response in 7 of 22 patients and objective stability in 20 of 29. Thus, 5-fluorouracil administered in an adequate weekly dosage is established as an effective single agent in some patients with stage D carcinoma of the bladder or prostate. However, there is no significant added benefit as measured by survival obtained for these patients by combining cyclophosphamide and doxorubicin with 5-fluorouracil.

Adenocarcinoma↗

Evaluation of the efficacy and tolerability of 0.5% fluorouracil cream and 5% fluorouracil cream applied to each side of the face in patients with actinic keratosis.

BACKGROUND: A new 0.5% fluorouracil cream has been developed that provides an alternative to the more highly concentrated topical formulations of fluorouracil that are currently available. OBJECTIVE: This was a comparison of the tolerability and efficacy of the 0.5% and 5% fluorouracil creams in the treatment of actinic keratosis (AK). METHODS: During this single-blind, randomized study, patients with > or =6 AK lesions were treated for 4 weeks with the 0.5% (once daily) and 5% (twice daily) fluorouracil creams applied to opposite sides of the face. After the end of treatment, patients were followed for an additional 4 weeks. Efficacy variables included absolute and percent reductions in AK lesions from baseline and total clearance of AK lesions. A questionnaire was used to evaluate patients' treatment preferences. Tolerability was evaluated through continuous monitoring of adverse events. RESULTS: Treatment with 0.5% fluorouracil cream reduced the number of AK lesions from 11.3 at baseline to 2.5 at the end of the 4-week follow-up phase, compared with a reduction from 10.3 to 4.2 lesions after treatment with 5% fluorouracil cream. The reduction was significantly greater with the 0.5% cream compared with the 5% cream (P = 0.044). The 0.5% cream was as effective as the 5% cream in terms of the percent reduction in AK lesions from baseline (67% and 47%, respectively) and in achieving total clearance of AK lesions (both treatments, approximately 43% of patients). Both treatments were associated with similar degrees of investigator-rated irritation; however, patients preferred the 0.5% cream because they felt it was more tolerable (P = 0.003), easier to apply, and had a once-daily application schedule. Although all patients experienced facial irritation in association with both creams, fewer patients treated with the 0.5% cream reported symptoms of facial irritation. CONCLUSIONS: In this study, 0.5% fluorouracil cream once daily was at least as effective as 5% fluorouracil cream twice daily in terms of the percent reduction in AK lesions and total clearance of AK lesions; it was more effective than the 5% cream in reducing the absolute number of AK lesions from baseline. Patients preferred the 0.5% cream to the 5% cream.

Administration, Topical↗

The results of a phase II randomized trial comparing 5-fluorouracil and 5-fluorouracil plus alpha-interferon: observations on the design of clinical trials for androgen-independent prostate cancer.

The therapeutic benefit of chemotherapy in androgen independent prostate cancer is limited. 5-Fluorouracil has been reported to have modest antitumor activity in androgen independent prostate cancer. Although alpha-interferon is inactive as a single agent in prostate cancer, preclinical data indicate that it increases the in vitro cytotoxicity of 5-fluorouracil against a variety of malignant cells. We evaluated the relative antitumor activity and tolerance of 5-fluorouracil versus 5-fluorouracil plus alpha-interferon in 50 patients with histologically confirmed metastatic adenocarcinoma of the prostate. These patients had progressive disease in the presence of castrate levels of testosterone. A prospective randomized phase II open labeled trial was performed because of the difficulty in measuring responses in patients with metastatic prostate cancer. Of 23 patients treated with 5-fluorouracil alone and 28 treated with 5-fluorouracil plus alpha-interferon 17 and 23, respectively, were evaluable for response and toxicity, and 5 and 5, respectively, were evaluable for toxicity only. Only 2 of 17 (11.7%) and 4 of 23 (17%) patients, respectively, showed a greater than 50% decrease in serum prostate specific antigen (no significant difference). There was no difference in duration of response or duration of survival between the 2 groups (mean duration of response 8.64 and 6.17 weeks, respectively, and mean duration of survival 33.70 and 38.65 weeks, respectively). Both regimens caused significant morbidity (mucositis and neurotoxicity) and 3 treatment related deaths at the high 5-fluorouracil doses. 5-Fluorouracil alone and with alpha-interferon at the doses used have minimal antitumor activity against androgen independent prostate cancer and, therefore, should not be tested further in these patients. Androgen independent prostate cancer selected using our criteria is a rapidly progressive disease, and these patients are an ideal target population for phase II studies.

Adenocarcinoma↗

Prodrugs of 5-fluorouracil. V. 1-Alkoxycarbonyl derivatives as potential prodrug forms for improved rectal or oral delivery of 5-fluorouracil.

The hydrolysis and physicochemical properties of seven 1-alkoxycarbonyl derivatives of 5-fluorouracil were studied to assess their potential as prodrugs with the aim of enhancing the delivery characteristics of the parent drug. All derivatives were hydrolyzed to quantitatively yield 5-fluorouracil. The pH-rate profiles for the hydrolysis were measured. The rates of hydrolysis were markedly accelerated in the presence of plasma, affording half-lives of hydrolysis less than 4 min in 80% human plasma. The derivatives were more lipophilic than 5-fluorouracil but the aqueous solubility was only slightly reduced or, for one derivative, even greater than that of 5-fluorouracil. A preliminary absorption study in rabbits showed an absolute bioavailability of 5-fluorouracil of 100% following rectal administration of 1-(butoxycarbonyl)-5-fluorouracil as compared with no absorption following administration of 5-fluorouracil itself. The potential utility of the prodrug derivatives to enhance the oral and/or rectal delivery of the parent drug is suggested.

Animals↗

5-Fluorouracil dose intensity increase in 5-fluorouracil and leucovorin combination: results of a phase II study.

It was our intention to verify if in the combination of 5-fluorouracil and leucovorin, the fluoropyrimidine dose intensity is an important determinant of response as noted by Hryniuk when 5-fluorouracil was given alone. By employing the Machover regimen but with cycles repeated every three weeks, a 5-fluorouracil projected dose intensity of 616 mg/m2/wk was obtained. It approximates the maximum tolerated dose for this drug when used alone by i.v. bolus. 50 patients entered this study and 48 were evaluable for response and toxicity. The overall response rate was 29% (five complete responses and nine partial responses). The dose limiting toxicity was gastrointestinal rather than myelosuppression. 5-fluorouracil dose reduction was needed in seven patients. The mean delivered dose intensity of 5-fluorouracil was 610 mg/m2/wk (582 mg/m2/wk in patients in whom 5-fluorouracil was reduced for toxicity and 616 mg/m2/wk in the others). Our results do not seem to show any advantage in the maximization of 5-fluorouracil dose intensity. Furthermore, in an analysis of data from the literature we did not find any difference in response rate in relation to dose intensity in the 5-fluorouracil/leucovorin combination.

Antineoplastic Combined Chemotherapy Protocols↗

A novel 0.5% fluorouracil cream is minimally absorbed into the systemic circulation yet is as effective as 5% fluorouracil cream.

Recent in vitro and in vivo studies compared the absorption of a 0.5% fluorouracil cream with that of a 5% fluorouracil cream, following topical application to the skin. Both studies demonstrated that fluorouracil is minimally absorbed into the systemic circulation. Despite a one-tenth concentration difference between formulations, the cumulative amount of fluorouracil excreted in the urine of patients treated with the 0.5% cream was one fortieth that of patients treated with the 5% cream. Interestingly, higher percentages of fluorouracil were retained in the skin following application of the 0.5% cream compared with the 5% cream, suggesting that delivery of the 0.5% cream may be more targeted to the affected area. Other studies have demonstrated that the 0.5% cream is as effective as the 5% cream for the treatment of actinic keratoses (AKs) and has a more favorable tolerability profile. Therefore, this new 0.5% fluorouracil cream may be a safer, yet equally effective treatment alternative.

Administration, Topical↗

Comparative studies on the metabolism of 2-(tetrahydrofuryl)-5-fluorouracil and 5-fluorouracil.

5=Fluorouracil inhibited DNA synthesis markedly using various DNA precursors such as deoxyuridine, orotic acid, uracil, and uridine except for thymidine. 2-(Tetrahydrofury)-5-fluorouracil (FT-207) did not inhibit DNA synthesis with any of the precursors tested. The metabolisms of 5-fluorouracil and FT-207 in mice and rats were studied. When administered intravenously 5-fluorouracil was rapidly degraded to fluoro-beta-alanine in both mice and rats, while at most 70% of FT-207 was slowly degraded after a prolonged period. The metabolites of FT-207 were found to be 5-fluorouracil and fluoro-beta-alanine in both species of animals. In vitro degradation of FT-207 into 5-fluorouracil was observed mainly in the microsomal fraction in the presence of NADPH. This result suggested that microsomal electron-transport system was concerned with the degradation of FT-207.

Alanine↗

Synthesis and evaluation of N-acyl-2-(5-fluorouracil-1-yl)-D,L-glycine as a colon-specific prodrug of 5-fluorouracil.

N-nicotinyl-2-(5-fluorouracil-1-yl)-D,L-glycine (NFG) and N-isonicotinyl-2-(5-fluorouracil-1-yl)-D,L-glycine (INFG) were synthesized as colon-specific prodrugs of 5-fluorouracil (5-FU). As N-aromatic acyl amides of glycine, they are expected to be stable in the upper intestine and delivered to the colon as an intact form if they are nonabsorbable. Microbial hydrolysis of amide bond in the colon will give 2-(5-fluorouracil)-D,L-glycine, which releases 5-FU by spontaneous decomposition. NFG and INFG were soluble in water and stable in pH 1.2 and 7.4 buffer solutions. The apparent partition coefficient of NFG or INFG in 1-octanol/pH 7.4 phosphate buffer solution at 37 degrees was 0.025 or 0.024, respectively. On incubation with cecal contents of rats, conversion of NFG or INFG proceeded only 9 or 5% in 8 h, respectively, producing 5-FU and a metabolite. The metabolite formation was inhibited in the presence of diazouracil, a dihydrouracil dehydrogenase inhibitor. The HPLC retention time of the metabolite from the incubation of 5-FU, NFG, or INFG with cecal contents was identical to dihydro-5-fluorouracil (dihydro-5FU). When N-nicotinyl-2-hydroxy-D,L-glycine methyl ester (NHGM) was incubated with the cecal contents, the extent of amide bond hydrolysis was 85% in 24 h. The result suggested that steric hindrance imposed by 5-FU at 2-position of glycine retarded the hydrolysis of the amide bond in NFG or INFG and suppressed the prodrug conversion.

Animals↗

Fluorouracil Filtering Surgery Study one-year follow-up. The Fluorouracil Filtering Surgery Study Group.

Two hundred thirteen patients participated in the Fluorouracil Filtering Surgery Study, a randomized clinical trial, to determine the efficacy and safety of subconjunctivally injected 5-fluorouracil after filtering surgery in eyes with poor prognoses. Twenty-eight (27%) of the 105 eyes in the 5-fluorouracil group and 54 (50%) of the 108 eyes in the standard group were classified as failures, defined by reoperation for control of intraocular pressure during the first year or an intraocular pressure greater than 21 mm Hg at the one-year visit (P = .0007, Mantel-Haenszel chi-square). Corneal epithelial toxicity and transient visual acuity loss were more common in the 5-fluorouracil group (P less than .001, chi-square); however, the visual acuities and the mean visual field sensitivities were not significantly different at one year. We recommend the use of subconjunctivally injected 5-fluorouracil after trabeculectomy in eyes with uncontrolled glaucoma and poor prognoses, specifically after previous cataract extraction or unsuccessful filtering surgery.

Adult↗

Loss of tRNA 5-methyluridine methyltransferase and pseudouridine synthetase activities in 5-fluorouracil and 1-(tetrahydro-2-furanyl)-5-fluorouracil (ftorafur)-treated Escherichia coli.

Transfer RNAs from Escherichia coli B treated with either 5-fluorouracil or its analog, 1-(tetrahydro-2-furanyl)-5-fluorouracil (ftorafur), contain low levels of 5-fluorouracil, but are grossly deficient in pseudouridine and 5-methyluridine. The enzymes responsible for the formation of these two modified nucleosides, tRNA pseudouridine synthetase and (5-methyluridine)-methyltransferase, show substantially reduced activity levels in extracts from ftorafur- and 5-fluorouracil-treated cells relative to preparations from normal cells. When these tRNA-modifying activities are examined in vitro, both are inhibited by the addition of fluorouridine-containing tRNAs to the reaction mixtures. Pseudouridine synthetase activity shows potent inhibition. These inhibitory properties of fluorouridine-containing tRNAs, plus the inability of tRNA (5-methyluridine)-methyl-transferase to efficiently use fluorouridine-containing tRNAs as substrates, appear to account for the deficiency of 5-methyluridine and pseudouridine in tRNAs from cells containing low levels of 5-fluorouracil.

Escherichia coli↗

Five-year follow-up of the Fluorouracil Filtering Surgery Study. The Fluorouracil Filtering Surgery Study Group.

PURPOSE: To determine the efficacy and safety of subconjunctival 5- fluorouracil injections after trabeculectomy in patients with poor prognoses, to determine risk factors for surgical failure and to examine the relationship of intraocular pressure and visual function. METHODS: In this multicenter clinical trial, 213 patients with previous cataract surgery or previous failed filtering surgery were randomly assigned to receive either trabeculectomy alone or trabeculectomy with postoperative subconjunctival 5-fluorouracil injections. Measurements of intraocular pressure, visual acuity, and visual fields were performed throughout the five years, with the clinician masked to the treatment group. Failure was defined as a reoperation to control intraocular pressure or an intraocular pressure greater than 21 mm Hg at or after the first-year examination. RESULTS: Fifty-four (51%) of the 105 eyes in the 5-fluorouracil group and 80 (74%) of the 108 eyes in the standard filtering surgery group were classified as failures (P < .001, Mantel-Cox survival analysis). Risk factors for failure include high intraocular pressure, a short time interval after the last procedure involving a conjunctival incision, the number of procedures with conjunctival incisions, and Hispanic ethnicity. Patients in both treatment groups with controlled intraocular pressures were more likely to maintain visual acuity. Patients in the 5-fluorouracil group had a higher risk of late-onset bleb leaks (9% nine of 105) than those in the standard filtering surgery group (2% two of 108) (P = .032, Fisher's exact test). CONCLUSIONS: We recommend the use of subconjunctival 5-fluorouracil after trabeculectomy in eyes after previous cataract surgery or unsuccessful filtering surgery, but caution against its routine use in patients with good prognoses.

Cataract Extraction↗

Leucovorin + 5-fluorouracil plus dipyridamole in leucovorin + 5-fluorouracil-pretreated patients with advanced colorectal cancer: a pilot study of three different dipyridamole regimens.

Dipyridamole, an inhibitor of nucleoside transport, increases the activity of 5-fluorouracil in a dose-dependent manner. The purpose of the present study was to determine whether dipyridamole with 5-fluorouracil and leucovorin gave an improved therapeutic outcome. Sixty patients entered in the present pilot study had previously received 5-fluorouracil (450 mg/m2) and leucovorin (100 mg/m2), every week, and relapsed during this treatment, which ended at least 6 weeks prior to study entry. Dipyridamole was administered at three different dosing schedules (DS) and methods of administration in three groups of patients. DS I: dipyridamole, 30 mg/m2 in normal saline solution, in 90 min iv infusion, followed by leucovorin, 100 mg/m2 iv push, followed by 5-fluorouracil, 450 mg/m2 in normal saline solution, in 60 min iv infusion, dipyridamole tablets (75 mg) every 12 hrs, continuously during the time of chemotherapy. DS II: dipyridamole, 50 mg/m2 in normal saline solution, in 90 min iv infusion, and the rest was the same as DS I. DS III: without oral dipyridamole, patients received dipyridamole (50 mg/m2) iv in the same manner as in DS I and II. Treatment was continued until tumor progression or unacceptable toxicity. All patients (n = 60) entered in the present study were assessable for response and toxicity. No complete response was observed. No patient at DS I responded, whereas 2 patients at DS II and 3 at DS III had a partial response (P <0.1). Stable disease was found with DS I (n = 1), DS II (n = 8) and DS III (n = 9) (P <0.01). More patients progressed at DS I (n = 19) than at DS II (n = 10) and DS III (n = 8) (P <0.0007). The median duration of response was 11 weeks (range, 8-16). Time to progression was 17 weeks for DS I, 15 weeks (range, 10-19) for DS II, and 14 weeks (range, 11-21) for DS III (P = 0.43). Median survival did not differ significantly between DS I (29 weeks; range, 14-48), DS II(31.5 weeks; range, 17-63) and DS III (36 weeks; range, 16-58) (P = 0.2). Neutropenia was most severe with DS I (grade 2, P<0.01) and DS II (grade 1, P<0.05) and nausea/vomiting with DS I (grade 0, P < 0.0005, grade 1, P <0.0002, grade 2, P <0.02) and DS III (grade 3, P<0.0009). Diarrhea was most severe in DS II (grade 3, P <0.005). Mucositis was increased in DS II (grade 0, P <0.008), anorexia in DS II (grade 0, P <0.032) and fatigue in DS I (grade 0, P <0.003). More patients in DS I than with the other two DS experienced headache (P <0.044). According to the response achieved at DS III (15% partial response and 45% stable disease) and the toxicity which was well tolerated mainly in this DS (except for nausea and vomiting grade 3, P <0.009), it can be stated that DS III is the appropriate dose and the simplest schedule of administration (administration of dipyridamole during therapy only). In conclusion, it appears that dipyridamole might still have a role in enhancing the clinical activity of drugs involved in the inhibition of the thymidylate synthetase biochemical pathway and its activity in combination with these agents (5-fluorouracil + leucovorin) as frontline treatment should therefore be explored in future phase II studies.

Aged↗

Randomized trial comparing weekly bolus 5-fluorouracil plus leucovorin versus monthly 5-day 5-fluorouracil plus leucovorin in metastatic colorectal cancer.

BACKGROUND/AIMS: The purpose of this study was to compare the efficacy and toxicity profiles of weekly intravenous (i.v.) bolus injection of 5-fluorouracil plus low-dose leucovorin with the Mayo Clinics' monthly 5-day schedule of 5-fluorouracil and leucovorin in the treatment of metastatic colorectal cancer. METHODOLOGY: A total of 96 patients with previously untreated metastatic colorectal cancer were randomized to receive either a weekly i.v. bolus injection of 5-fluorouracil 400 mg/m2 plus leucovorin 20 mg/m2 (weekly arm), or i.v. bolus injection of 5-fluorouracil 425 mg/m2 plus leucovorin 20 mg/m2 for 5 consecutive days every 4 or 5 weeks (monthly arm). Therapy was continued until disease progression or unacceptable toxicity appeared. In the presence of disease progression, the study regimen was stopped and second-line treatment was instituted after the patient was discontinued from this study. RESULTS: There was no significant difference of response rates between both regimens. The response rate were 14.3% in the weekly arm (2 CR and 5 PR, 95% CI: 2.6-25.2%) and 10.6% in the monthly arm (1 CR and 4 PR; 95% CI: 6.5-32.3%), respectively (P = 0.8957). The survival times were also similar between the two (P = 0.4207, log-rank test). The median survival were 15.8 months in the monthly arm and 18.4 months in the weekly arm. Hematologic toxicity was minimal in both arms. However, the monthly arm produced a higher toxicity in severe (grade 3-4) diarrhea (14.9% vs. 2%; P = 0.029) and stomatitis (8.5% vs. 0; P = 0.054). CONCLUSIONS: Weekly bolus injection of 5-fluorouracil and low-dose leucovorin achieved a similar response rate and survival as compared with the Mayo Clinics' monthly 5-day schedule, but severe toxicity was less commonly seen using the weekly regimen. As current chemotherapeutic treatment for metastatic colorectal cancer is largely palliative rather than curative, the weekly bolus regimen may be a more favorable approach in managing metastatic colorectal cancer.

Aged↗

Metabolic fate on 1-hexylcarbamoyl-5-fluorouracil and 5-fluorouracil in mice bearing ascites sarcoma 180.

Patterns of metabolism and disposition in plasma of tumor-bearing mice after oral administration of [6(-14)C]1-hexylcarbamoyl-5-fluorouracil ([6(-14)C]HCFU) resembled those in plasma of normal mice, but elimination of [6(-14)C]HCFU and 5-fluorouracil (FUra) was slower in tumor-bearing mice. The level of 1-(5-hydroxyhexylcarbamoyl)-5-fluorouracil (HHCFU) was lower in tumor-bearing mice. Also detected in plasma were [6(-14)C]HCFU, HHCFU, 1-(3-carboxypropylcarbamoyl)-5-fluorouracil, FUra, 5,6-dihydro-5-fluorouracil, and alpha-fluoro-beta-alanine. FUra originating from [6(-14)C]HCFU was retained over 6 hours, whereas intact FUra after [6(-14)C]FUra administration disappeared within 2 hours. The pattern of metabolism in ascitic fluid was similar to that in plasma after [6(-14)C]HCFU and [6(-14)C]FUra administration, but FUra was retained for a longer period in ascitic fluid. In sarcoma 180 cells, the maximum concentration of total radioactivity was observed 1 or 2 hours after [6(-14)C]FUra or [6(-14)C]HCFU administration, respectively, and the level of intact HCFU was very low. The principal metabolites were nucleotides that were maintained for a long period after administration of both compounds. The pattern of other metabolites after [6(-14)C]HCFU administration was also similar to that after [6(-14)C]FUra administration.

Administration, Oral↗