2--2--difluoro-2--deoxyuridine and Carcinoma--Non-Small-Cell-Lung

To study the impact of the 79A>C polymorphism in the cytidine deaminase (CDA) gene on the pharmacokinetics of gemcitabine and its metabolite 2',2'-difluorodeoxyuridine (dFdU) in non-small-cell lung cancer (NSCLC) patients.. Patients (n = 20) received gemcitabine 1,125 mg/m(2) as a 30 min i.v. infusion as part of treatment for NSCLC. Plasma samples were collected during 0-6 h after gemcitabine administration. Gemcitabine and dFdU were quantified by high performance liquid chromatography with ultraviolet detection. The CDA 79A>C genotype was determined with PCR and DNA sequencing.. Gemcitabine was rapidly cleared from plasma and undetectable after 3 h. The allele frequency of the 79A>C polymorphism was 0.40. Diplotypes were distributed as A/A n = 8, A/C n = 8 ,and C/C n = 4. No significant differences were found between the different CDA genotypes and gemcitabine or dFdU AUC, clearance, or half-life.. The 79A>C polymorphism in the CDA gene does not have a major consistent and signficant impact on gemcitabine pharmacokinetics.

Topics: Adult; Aged; Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Non-Small-Cell Lung; Cytidine Deaminase; Deoxycytidine; Female; Floxuridine; Gemcitabine; Gene Frequency; Genotype; Humans; Lung Neoplasms; Male; Metabolic Clearance Rate; Middle Aged; Polymorphism, Single Nucleotide

Gemcitabine, 2',2'-difluoro-2'-deoxycytidine (dFdC) is a pyrimidine antimetabolite employed against several human malignancies. It undergoes intracellular activation to the pharmacologically active triphosphate form (dFdCTP) and metabolic inactivation to the metabolite 2',2'-difluorodeoxyuridine (dFdU). In order to investigate the human plasma pharmacokinetics of dFdC and dFdU, we developed and validated an HPLC-MS/MS method, adding 2'-deoxycytidine as internal standard and simply precipitating the protein with acetonitrile. The method requires a small sample (125 microl), and it is rapid and selective, allowing good resolution of peaks from the plasma matrix in only 7 min. It is sensitive, precise and accurate, with overall precision, expressed as CV%, always less than 10.0% for both analytes and high recovery: > or = 80%. The limits of detection for dFdC and dFdU were 0.1 and 1.1 ng/ml, but considering the high concentrations in the plasma of patients investigated, we set the limit of quantitation at 20 ng/ml (0.08 microM) for dFdC and 250 ng/ml for dFdU, and validated the assay up to the dFdC concentration of 6.0 microg/ml (22.8 microM). The method was successfully used to study the drug pharmacokinetics in patients with advanced non-small-cell lung cancer in a phase II trial with gemcitabine administered as a fixed dose-rate infusion.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Non-Small-Cell Lung; Chromatography, High Pressure Liquid; Cisplatin; Deoxycytidine; Floxuridine; Gemcitabine; Humans; Lung Neoplasms; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry

Our objective was to study the feasibility of schedule- and dose-intensive cisplatin plus gemcitabine in patients with non-small cell lung cancer (NSCLC) when given on 1 day in four 2-weekly cycles. Cisplatin was administered as a 3 h i.v. infusion followed by gemcitabine as a 30-min i.v. infusion on the same day, every 2 weeks. An interval of 1 h between the two infusions was applied. Patients received four courses without any break. An interpatient dose-escalation scheme was used. The starting dose was 87.5 mg/m of cisplatin and 1350 mg/m of gemcitabine. The pharmacokinetics of cisplatin and gemcitabine were determined in plasma and white blood cells. In total, 23 patients were included in the study. Median age of the patients was 56 years (range 27-76) and most patients were in good clinical condition. Thirteen patients received all planned courses. Dose-limiting toxicity was Common Toxicity Criteria grade 2 ototoxicity. The maximum tolerated dose was established at cisplatin 90 mg/m in combination with gemcitabine 1500 mg/m. This short induction schedule is practical and convenient for the patient. We conclude that the combination of cisplatin at a dose intensity of 51 mg/m/week followed by gemcitabine (1500 mg/m) on the same day is clinically feasible in NSCLC patients when given as a 2-weekly cycle.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; Carcinoma, Non-Small-Cell Lung; Cisplatin; Deoxycytidine; DNA Adducts; Dose-Response Relationship, Drug; Floxuridine; Gemcitabine; Humans; Leukocytes; Male; Middle Aged; Platinum; Treatment Outcome