Phase I pharmacokinetic, food effect, and pharmacogenetic study of oral irinotecan given as semisolid matrix capsules in patients with solid tumors.

PURPOSE: To characterize the maximum-tolerated dose, recommended dose, dose-limiting toxicities (DLT), pharmacokinetic profile, and food effect of orally administered irinotecan formulated as new semisolid matrix capsules. EXPERIMENTAL DESIGN: Irinotecan was given orally in fasted patients once daily for 5 consecutive days and repeated every 3 weeks. Patients were randomly assigned to take the drug along with a high-fat, high-calorie breakfast for the administration at day 1 of the first or second cycle. Dosages tested were 70 and 80 mg/m(2)/day. RESULTS: Twenty-five patients received 101 cycles of therapy (median two cycles, range 1-15). During the first cycle, grade 3 delayed diarrhea and grade 3 fever were the DLTs at the dosage of 80 mg/m(2)/day in three out of five patients. Hematologic and nonhematologic toxicities were mild to moderate. Exposure to the active metabolite SN-38 was relatively high compared with i.v. infusion, but no relevant accumulation was observed. Food had no significant effect on irinotecan pharmacokinetics. One confirmed partial remission and 10 disease stabilizations were observed in previously treated patients. No association was found between the UGT1A1*28 genotype and the risk of severe irinotecan-induced toxicity. CONCLUSIONS: For oral irinotecan, a dose of 70 mg/m(2)/day for 5 consecutive days every 3 weeks is recommended for further studies. Delayed diarrhea was the main DLT, similar to that observed with intravenously administered irinotecan. This study confirms that oral administration of irinotecan is feasible and may have favorable pharmacokinetic characteristics.

Phase I and pharmacokinetic study of oral irinotecan given once daily for 5 days every 3 weeks in combination with capecitabine in patients with solid tumors.

PURPOSE: To assess the maximum tolerated dose, dose-limiting toxicity, pharmacokinetics, and preliminary antitumor activity of oral irinotecan given in combination with capecitabine to patients with advanced, refractory solid tumors. PATIENTS AND METHODS: Patients were treated from day 1 with irinotecan capsules given once daily for 5 consecutive days (50 to 60 mg/m2/d) concomitantly with capecitabine given twice daily for 14 consecutive days (800 to 1,000 mg/m2); cycles were repeated every 21 days. RESULTS: Twenty-eight patients were enrolled and received 155 cycles of therapy (median, five cycles; range, one to 18 cycles). With irinotecan 60 mg/m2/d and capecitabine 2 x 800 mg/m2/d, grade 3 delayed diarrhea in combination with grade 2 nausea (despite maximal antiemetic support) and grade 3 anorexia and colitis, were the first-cycle dose-limiting toxicities in two of six patients, respectively. At the recommended doses (irinotecan 50 mg/m2/d; capecitabine 2 x 1,000 mg/m2/d), side effects were mostly mild to moderate and uniformly reversible. Pharmacokinetic analysis showed that there was no interaction between oral irinotecan and capecitabine, and that body-surface area was not significantly contributing to the observed pharmacokinetic variability. Confirmed partial responses were observed in two patients with gallbladder carcinoma and in one patient with melanoma. Disease stabilization was noted in 16 patients. CONCLUSION: The recommended phase II doses for oral irinotecan and capecitabine are 50 mg/m2/d for 5 consecutive days, and 2 x 1,000 mg/m2/d for 14 consecutive days repeated every 3 weeks, respectively.

Phase I and pharmacokinetic study of DE-310 in patients with advanced solid tumors.

PURPOSE: To assess the maximum-tolerated dose, toxicity, and pharmacokinetics of DE-310, a macromolecular prodrug of the topoisomerase I inhibitor exatecan (DX-8951f). in patients with advanced solid tumors. EXPERIMENTAL DESIGN: Patients received DE-310 as a 3-hour infusion once every 2 weeks (dose, 1.0-2.0 mg/m(2)) or once every 6 weeks (dose, 6.0-9.0 mg/m(2)). Because pharmacokinetics revealed a drug terminal half-life exceeding the 2 weeks administration interval, the protocol was amended to a 6-week interval between administrations also based on available information from a parallel trial using an every 4 weeks schedule. Conjugated DX-8951 (the carrier-linked molecule), and the metabolites DX-8951 and glycyl-DX-8951 were assayed in various matrices up to 35 days post first and second dose. RESULTS: Twenty-seven patients were enrolled into the study and received a total of 86 administrations. Neutropenia and grade 3 thrombocytopenia, and grade 3 hepatotoxicity with veno-occlusive disease, were dose-limiting toxicities. Other hematologic and nonhematologic toxicities were mild to moderate and reversible. The apparent half-life of conjugated DX-8951, glycyl-DX-8951, and DX-8951 was 13 days. The area under the curve ratio for conjugated DX-8951 to DX-8951 was 600. No drug concentration was detectable in erythrocytes, skin, and saliva, although low levels of glycyl-DX-8951 and DX-8951 were detectable in tumor biopsies. One patient with metastatic adenocarcinoma of unknown primary achieved a histologically proven complete remission. One confirmed partial remission was observed in a patient with metastatic pancreatic cancer and disease stabilization was noted in 14 additional patients. CONCLUSIONS: The recommended phase II dose of DE-310 is 7.5 mg/m(2) given once every 6 weeks. The active moiety DX-8951 is released slowly from DE-310 and over an extended period, achieving the desired prolonged exposure to this topoisomerase I inhibitor.

Liquid chromatographic assays for DE-310, a novel camptothecin analog, and two major enzymatic products in human matrices.

Assays were developed for determination of DE-310, a carboxymethyldextran polyalcohol conjugate of the topoisomerase I inhibitor DX-8951 (exatecan) and two enzymatic products (i.e. glycyl-DX-8951 and unconjugated DX-8951) in human whole blood, erythrocytes and saliva. Sample pretreatment involved a single protein-precipitation step, followed by a thermolysin-mediated deconjugation for the parent molecule. Separation of the compounds was achieved on an Inertsil ODS-80A column (150 mm x 4.6 mm i.d.; 5 microm PS), using isocratic elution. The column effluent was monitored at excitation and emission wavelengths of 375 and 445 nm, respectively. Validation results indicated that the methods are accurate and precise at lower limits of quantitation of 0.5-6.9 ng/ml. The methods were used to study the blood distribution and salivary concentrations in patients receiving DE-310.