Phase I pharmacokinetic and pharmacodynamic study of Carboplatin and topotecan administered intravenously every 28 days to patients with malignant solid tumors.

PURPOSE: Preclinical studies have shown that the combination of topotecan and carboplatin is synergistic. To evaluate the schedule dependency of this interaction, the following phase I trial was designed to determine the safety and maximum tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of carboplatin and topotecan in patients with malignant solid tumors. EXPERIMENTAL DESIGN: In part 1, patients received carboplatin on day 1 and topotecan on days 1, 2, and 3 (C-->T schedule). In part 2, topotecan was administered on days 1, 2, and 3, followed by carboplatin on day 3 (T-->C schedule). Pharmacokinetics were determined in plasma and DNA topoisomerase I catalytic activity and Pt-DNA adducts in WBC and tumor tissue. RESULTS: Forty-one patients were included. Dose-limiting toxicities during the C-->T schedule were grade 4 thrombocytopenia and febrile neutropenia (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 4 min mg/mL; topotecan, 0.5 mg/m(2)/d). Dose-limiting toxicities during the T-->C schedule included grade 4 neutropenia, thrombocytopenia, neutropenic fever, and grade 4 nausea and vomiting (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 6 min mg/mL; topotecan, 0.9 mg/m(2)/d). One complete response and five partial responses were observed. The clearance of and exposure to carboplatin and topotecan did not depend on the sequence of drug administration. No schedule-dependent effects were seen in Pt-DNA levels and DNA topoisomerase I catalytic activity in WBC and tumor tissue. However, myelotoxicity was clearly more evident in the C-->T schedule. CONCLUSION: The T-->C schedule was better tolerated because both hematologic and nonhematologic toxicities were milder. Other pharmacodynamic factors than the ones investigated must explain the schedule-dependent differences in toxicities.

Phase I study of an oral formulation of irinotecan administered daily for 14 days every 3 weeks in patients with advanced solid tumours.

A phase I study was conducted with oral irinotecan given daily for 14 days every 3 weeks in 45 patients with solid tumours to establish the maximum tolerated dose (MTD), toxicity, preliminary antitumour response and pharmacokinetics. Irinotecan was administered orally as a powder-filled capsule at doses ranging from 7.5 to 40 mg/m2 per day. Tumours were predominantly colorectal (30) together with 10 other gastrointestinal, 2 breast, 2 small cell lung and 1 ovarian. All but three patients had received prior chemotherapy. The median number of administered cycles was 3 (range 1-19). Gastrointestinal toxicities (grade 3 nausea, grade 3/4 vomiting and diarrhoea) and one incidence of grade 3 asthenia were dose limiting. There were no grade 3/4 haematological toxicities. The MTD was 30 mg/m2 per day. There were two documented partial responses, one in a patient with cancer of the small intestine and the other in a patient with colon cancer. Stable disease was seen in 16 patients (35.5%). Peak concentrations of irinotecan and metabolite SN-38 were reached within 2.0-2.4 h. The metabolic ratio of SN-38 AUC to irinotecan AUC was 0.17+/-0.10 (mean+/-SD). The dose recommended for phase II studies is 30 mg/m2 per day administered daily for 14 days every 3 weeks.

Randomized phase I clinical and pharmacologic study of weekly versus twice-weekly dose-intensive cisplatin and gemcitabine in patients with advanced non-small cell lung cancer.

PURPOSE: To establish the maximum dose intensity of cisplatin plus gemcitabine on a weekly or two-weekly schedule in patients with advanced non-small cell lung cancer (NSCLC). METHODS: Patients with NSCLC stage IIIB or IV were randomized to receive weekly or two-weekly courses of gemcitabine on day 1 and cisplatin on day 2. An interpatient dose escalation scheme was used, and pharmacokinetics were determined for both agents in plasma and WBCs. RESULTS: Seventy-three patients were included, 32 on the weekly schedule and 41 on the two-weekly schedule. Fifty patients received all planned courses. Dose-limiting toxicities were leukocytopenia, neutropenia, and trombocytopenia on the weekly schedule and ototoxicity on the two-weekly schedule. Most common nonhematological toxicities consisted of nausea, vomiting, and fatigue. The highest dose intensity of cisplatin could be achieved on the two-weekly schedule, and therefore, further development of the weekly schedule was abandoned. The maximum tolerated dose was established at 1500 mg/m(2) gemcitabine in combination with cisplatin 90 mg/m(2). More than half (53%) of patients achieved an objective response on the two-weekly schedule, versus 23% in the weekly treatment arm. The pharmacokinetic studies revealed a significant interaction: gemcitabine reduced both GG and AG platinum-DNA intrastrand adducts in WBCs. CONCLUSION: The combination of gemcitabine (1500 mg/m(2)) with cisplatin at a dose intensity of 50 mg/m(2)/week is feasible on a two-weekly administration scheme in NSCLC patients.

High-performance liquid chromatographic analysis of the anticancer drug irinotecan (CPT-11) and its active metabolite SN-38 in human plasma.

A rapid, sensitive, and specific high-performance liquid chromatography (HPLC) method for the simultaneous determination of irinotecan (CPT-11) and its active metabolite SN-38 in human plasma is described. The analytes are quantified as the totals of their carboxylate and lactone form. The sample pretreatment consisted of a simple protein precipitation with acetonitrile-methanol (1:1, v/v), after which CPT-11 and SN-38 were quantitatively converted to their carboxylate form by adding 0.01 mol/L sodium tetraborate (pH, 9). Chromatography was carried out on a Zorbax SB-C18 column with fluorescence detection. The method has been validated, and stability tests under various clinically relevant conditions have been performed. The lower limit of quantification (LLOQ) was 5.0 ng/mL for CPT-11 and 0.5 ng/mL for SN-38. Standard concentration ranges were linear between 5 and 1,500 ng/mL for CPT-11 and between 0.5 and 100 ng/mL for SN-38. This assay is simple, rapid, and very useful for therapeutic monitoring of CPT-11 and SN-38.

Development of an optimal pharmacokinetic sampling schedule for rubitecan administered orally in a daily times five schedule.

PURPOSE: Our aim was to develop an optimal sampling strategy for the description of the pharmacokinetics of rubitecan and its active metabolite 9-aminocamptothecin (9-AC) for use in phase II/III studies with oral rubitecan administered in a daily times five schedule. METHODS: Concentration-time data of rubitecan and 9-AC were obtained from 14 patients who had received 1.5 mg/m(2) per day rubitecan orally. Population pharmacokinetic analysis of both the parent and the metabolite was performed using the nonlinear mixed effect modelling program (NONMEM). Optimal sampling points were selected on the basis of the assessed population pharmacokinetic parameters using a D-optimality algorithm. RESULTS: The pharmacokinetics of both rubitecan and 9-AC were adequately described with a one-compartment model. The absorption rate constant, apparent volume of distribution and apparent clearance of rubitecan were 0.81 h(-1), 50 l and 1.7 l/h, respectively. For 9-AC the corresponding values of the apparent volume of distribution and the elimination rate constant were 51 l and 0.102 h(-1). Interindividual variability of the pharmacokinetic parameters ranged from 38% to 49%. For the first dose, optimal sampling points were 1, 3, 5, 8 and 24 h after dosing. Monte Carlo simulations indicated that the sampling schedule produced parameter estimates which were unbiased and precise. CONCLUSIONS: An optimal sampling schedule was derived which allowed assessment of the pharmacokinetic parameters of both the parent compound and its metabolite 9-AC after oral administration of rubitecan.

Determination of 9-nitrocamptothecin and its metabolite 9-aminocamptothecin in human plasma using high-performance liquid chromatography with ultraviolet and fluorescence detection.

A high-performance liquid chromatography assay is described for the determination of the investigational anti-cancer drug 9-nitrocamptothecin (9-NC) and its metabolite 9-aminocamptothecin (9-AC) as the total of their lactone and carboxylate forms. The sample pre-treatment consisted of a deproteinisation step and a quantitative acid-catalyzed conversion of all 9-NC and 9-AC into their lactone forms and a subsequent solid-phase extraction. Redissolved extracts were analyzed on a Prodigy analytical column, using a mixture of methanol-phosphate buffer (pH 2.5). Detection was concomitantly performed with UV for 9-NC and fluorimetrically for 9-AC. The lower limit of quantifications were 10 ng/ml and 2.5 ng/ml for the determination of 9-NC and 9-AC, respectively, using 500 microl of plasma. The presented method was successfully applied to a clinical pharmacokinetic study.

Urinary and fecal excretion of topotecan in patients with malignant solid tumours.

PURPOSE: The objectives of the study were to determine the pharmacokinetics and routes of excretion of topotecan following intravenous or oral administration to patients with refractory solid tumours. METHODS: Patients were randomized to receive either oral (2.3 mg/m(2)) or intravenous (1.5 mg/m(2)) topotecan once daily for 5 days in course 1. Patients who received in course 1 oral topotecan received in course 2 intravenous topotecan on day 1 followed by oral topotecan on days 2 to 5. Patients who received in course 1 intravenous topotecan received in course 2 oral topotecan once daily for 5 days. Plasma pharmacokinetics were performed on day 1 of course 1 (all patients) and course 2 (only patients receiving intravenous topotecan on that day). In course 1, urine and feces were collected for up to 9 days after the first dosage. The amounts of topotecan and N-desmethyl topotecan in plasma, urine and feces were determined by validated high-performance liquid chromatographic assays. RESULTS: A total of 11 patients were enrolled in the study. Nine patients were evaluable for pharmacokinetics. Plasma pharmacokinetics were similar to those previously reported. The principal route of excretion was the urine, with approximately 49% of the intravenously administered topotecan dose and 20% of the oral dose collected in the urine as parent drug. Approximately 18% and 33% of the intravenous and oral dose, respectively, were recovered unchanged in the feces. Only small amounts of N-desmethyl topotecan were found in the excreta. CONCLUSIONS: Fecal and urinary excretion of unchanged topotecan were the major routes of topotecan elimination. Approximately 28% of the intravenous dose and 43% of the oral dose of topotecan were unaccounted for and eliminated through other routes.

Topoisomerase I levels in white blood cells of patients with ovarian cancer treated with paclitaxel-cisplatin-topotecan in a phase I study.

Topotecan stabilizes the topoisomerase I (Topo I) cleavable complex. We measured Topo I levels in white blood cells of patients with ovarian cancer treated with topotecan. Topotecan was given i.v. daily x 5 q 3 weeks in combination with paclitaxel (1 day before topotecan) and cisplatin (just prior topotecan). Our aim was to correlate Topo I levels to pharmacokinetics and toxicity. Topo I levels were determined using Western blotting and were expressed relative to the Topo I level present in 10 microg cell lysate of the human IGROV1 ovarian cancer cell line. We found no correlation between Topo I levels and (non-)hematological toxicity. Topo I levels after the fifth topotecan infusion were significantly negatively correlated with the AUC of topotecan (R = -0.64, p = 0.026), in contrast with Topo I levels prior to (R = -0.25, p = 0.4) and after (R = -0.30, p = 0.3) the first topotecan infusion. Topo I levels after the fifth topotecan infusion (48 +/- 27%, mean +/- SD) were higher than Topo I levels prior to and after the first topotecan infusion (3.0 +/- 4.7 and 2.7 +/- 3.6%, respectively) (p = 0.001). In conclusion, we detected a significant inverse correlation between Topo I level and topotecan AUC at day 5, and we found increasing Topo I levels during a daily x 5 schedule of treatment with topotecan.