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Tegafur, a prodrug of 5-fluorouracil (5-FU), is an oral fluorouracil antitumor drug used for the management of adenocarcinomas. It has an efficacy similar to that of intravenous 5-FU, with potential advantages in terms of convenience and quality of life for the patient and cost-effectiveness as compared with intravenous chemotherapy. The authors developed a high-performance liquid chromatography (HPLC) assay for the determination of tissue or plasma tegafur and 5-FU concentration in a single step extraction and a single HPLC injection. The retention times of 5-FU and tegafur were 5 and 16.5 minutes, respectively, and the internal standard retention times were 11.5 and 17.5 minutes for 5-bromouracil (5-BU) and beta-hydroxyethyltheophylline, respectively. The limit of quantification was 0.0125 microg/mL for 5-FU and 0.05 microg/mL for tegafur. The assay had good recovery (96.5% +/- 9.45% and 97.5% +/- 7.89% for 5-FU in plasma and tissue, respectively, and 88.5% +/- 12.17% and 104.9% +/- 8.77% for tegafur in plasma and tissue, respectively). Precision was good: the within-day and between-day standard deviation of the mean (RSD) for 5-FU (0.0125-5 microg/mL) and tegafur (0.5-150 microg/mL) was always <8%. The authors conclude that the method described here is ideally suited for the therapeutic monitoring of 5-FU and tegafur.

The purpose of this trial was to define the maximum tolerated duration (MTD), dose-limiting toxicity (DLT), regimen-related toxicities (RRT), and pharmacokinetics of gemcitabine infused at a fixed dose rate (FDR) of 10 mg/m2/min, combined with docetaxel/melphalan/carboplatin, using autologous stem cell transplantation (ASCT). The duration of gemcitabine infusion was incrementally escalated as a single treatment on day -6 or as 4 daily infusions on days -5 to -2. Gemcitabine was followed by docetaxel (300 or 350 mg/m2) on day -5, and then melphalan (50 mg/m2/day) and carboplatin (333 mg/m2/day) on days -4 to -2. Fifty-two patients with refractory tumors were accrued with a median age of 40 (range: 6-66), a median of 3 (1-6) prior chemotherapy regimens, and 3 (1-7) organs involved. The gemcitabine MTD was defined at 20 hours (total dose 12,000 mg/m2) on both schedules. The DLT was enteritis. Three patients died from aspiration, catheter-related sepsis, and enteritis, respectively. The tumor response rate was 91%, with 50% complete responses. At current 2-year median follow-up, the event-free and overall survival (EFS, OS) rates are 54% (median 26 months) and 79% (median not reached), respectively. Gemcitabine area under the curve (AUC), but not clearance, increased linearly with infusion duration, and correlated with grade 3 RRT. Docetaxel showed a linear increase of its AUC and similar clearance compared with prior reports at lower doses. In conclusion, ASCT-supported infusions of gemcitabine at FDR could be prolonged up to 20 hours. The resulting gemcitabine/docetaxel/melphalan/carboplatin combination was highly active in refractory cancers and should be further tested in disease-specific trials.

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