Quantification of docetaxel and its metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

RATIONALE: During drug development accurate quantification of metabolites in biological samples using mass spectrometry is often hampered by the lack of metabolites of chemically pure quality. However, quantification of metabolites can be useful for assessment and interpretation of (pre)clinical data. We now describe an approach to quantify docetaxel metabolites in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using docetaxel calibration standards. METHODS: Metabolites (M1/M3, M2 and M4) were generated using microsomal incubations. Retention times of docetaxel and its metabolites were assessed using an LC/UV assay and peak identification was performed by LC/MS(n). Samples containing isolated metabolites from human faeces were quantified by LC/UV and used as references for spiking human plasma samples. LC/MS/MS was applied to sensitively quantify docetaxel and its metabolites in human plasma using docetaxel calibration standards in a range of 0.25-500 ng/mL. RESULTS: Because ionisation of docetaxel and its metabolites differed, correction factors were established to quantify the metabolites using docetaxel calibration samples. During method validation, accuracy and precision of the metabolites were within ±7.7% and ≤17.6%, respectively, and within ±14.3% and ≤10.1%, respectively, for docetaxel. Metabolites were found to be unstable in human plasma at ambient temperature. After storage up to 1 year at -20 °C, recovered metabolite concentrations were within ±25%. CONCLUSIONS: Development and validation of an LC/MS/MS assay for the quantification of docetaxel and its metabolites M1/M3, M2 and M4 using docetaxel calibration standards is described. The same approach may be used for quantification of metabolites of other drugs by LC/MS/MS when chemically pure reference substances are unavailable.

Development and validation of LC-MS/MS assays for the quantification of bendamustine and its metabolites in human plasma and urine.

A sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) assay is described for the quantification of the anti-cancer agent bendamustine and its phase I metabolites γ-hydroxy-bendamustine (M3) and N-des-methylbendamustine (M4) and for its product of two-fold hydrolysis, dihydroxy-bendamustine (HP2), in human plasma and urine. Like most alkylating nitrogen mustards, bendamustine is prone to chemical hydrolysis in aqueous solution. To minimize degradation of bendamustine, urine samples were stabilized by a 100-fold dilution with human plasma and then processed identically to plasma samples. Sample aliquots of 200 µL were mixed with an internal standard solution and acidified before separation of the analytes from the biomatrix with solid phase extraction. Dried and reconstituted extracts were injected on a Synergi Hydro RP column for the analysis of bendamustine, M3 and M4 or a Synergi Polar RP column for the analysis of HP2. Gradient elution was applied using 5mM ammonium formate with 0.1% formic acid in water and methanol as mobile phases. Analytes were ionized using an electrospray ionisation source in positive mode and detected with a triple quadrupole mass spectrometer. The quantifiable range for bendamustine, M3 and M4 was 0.5-500 ng/mL in plasma and 0.5-50 µg/mL in urine, and that for HP2 was 1-500 ng/mL in plasma and 0.1-50 µg/mL in urine. The assays were accurate and precise, with inter-assay and intra-assay accuracies within ± 20% of nominal and CV values below 20% at the lower limit of quantification and within ± 15% of nominal and below 15% at the other concentration levels tested. These methods were successfully applied to evaluate the pharmacokinetic profile of bendamustine and its metabolites in cancer patients treated with bendamustine.

Development and validation of LC-MS/MS assays for the quantification of E7080 and metabolites in various human biological matrices.

To support clinical pharmacokinetic studies with the anticancer agent E7080 (lenvatinib), liquid chromatography tandem mass spectrometry (LC-MS/MS) methods were developed for the quantification of E7080 and four of its metabolites in human plasma, urine and faeces and of E7080 in whole blood. Cross-analyte interferences between metabolites and parent compound were expected and therefore accounted for early in the method development. Plasma, urine and faeces samples were extracted with acetonitrile. Chromatographic separation was achieved on a 50 mm × 2.1 mm I.D. XTerra MS C18 column, with a 0.2 mL/min flow and gradient elution starting with 100% formic acid in water, followed by an increasing percentage of acetonitrile. Whole blood samples were extracted with diethyl ether and extracts were injected on a 150 mm × 2.1mm I.D. Symmetry Shield RP8 column. Detection was performed using an API3000 triple quadrupole mass spectrometer, with a turbo ion spray interface, operating in positive ion mode. Using 250 µL of plasma, E7080 and its metabolites could be quantified between 0.25 and 50.0ng/mL. The quantifiable ranges of E7080 in whole blood, urine and faeces were 0.25-500 ng/mL, 1.00-500 ng/mL and 0.1-25µg/g, using sample volumes of 250 µL, 200 µL and 250 mg, respectively. Calibration curves in all matrices were linear with a correlation coefficient (r(2)) of 0.994 or better. At the lower limit of quantification, accuracies were within ±20% of the nominal concentration with CV values less than 20%. At the other concentrations the accuracies were within ±15% of the nominal concentration with CV values below 15%. The developed methods have successfully been applied in a mass balance study of E7080.

Validation of high-performance liquid chromatography-tandem mass spectrometry assays for the quantification of eribulin (E7389) in various biological matrices.

This paper presents specific and sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) assays for the quantification of the novel anticancer agent eribulin in human plasma, whole blood, urine and faeces. These assays, developed to support clinical pharmacological studies with the drug, quantify eribulin concentration ranges of 0.2-100ng/mL for plasma, 0.5-100 ng/mL for whole blood and urine and 0.1-25 µg/g for faeces, using sample volumes of 500 µL or 250 µg (faeces). Samples were prepared with liquid-liquid extraction, separated on a C18 column with gradient elution and analysed with a triple quadrupole MS, in positive ion mode. A structural analogue of eribulin was used as internal standard for the quantification. The assays were linear with correlation coefficients (r(2)) of 0.99 and better, whereby the deviation from nominal concentrations ranged from -8.2 to 8.9% with CV values of maximally 14.2%. Stability assessments demonstrated that eribulin is stable at -20°C in plasma, whole blood, urine and faeces for at least 38, 4, 10.5 and 5 months, respectively. In conclusion, the validation results show that the assays are specific and accurate and can therefore adequately be applied to support clinical studies of eribulin.

Phase I and pharmacological study of sequential intravenous topotecan and oral etoposide.

We performed a phase I and pharmacological study to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of a cytotoxic regimen of the novel topoisomerase I inhibitor topotecan in combination with the topoisomerase II inhibitor etoposide, and to investigate the clinical pharmacology of both compounds. Patients with advanced solid tumours were treated at 4-week intervals, receiving topotecan intravenously over 30 min on days 1-5 followed by etoposide given orally twice daily on days 6-12. Topotecan-etoposide dose levels were escalated from 0.5/20 to 1.0/20, 1.0/40, and 1.25/40 (mg m-2 day-1)/(mg bid). After encountering DLT, additional patients were treated at 3-week intervals with the topotecan dose decreased by one level to 1.0 mg m-2 and etoposide administration prolonged from 7 to 10 days to allow further dose intensification. Of 30 patients entered, 29 were assessable for toxicity in the first course and 24 for response. The DLT was neutropenia. At doses of topotecan-etoposide 1.25/40 (mg m-2)/(mg bid) two out of six patients developed neutropenia grade IV that lasted more than 7 days. Reduction of the treatment interval to 3 weeks and prolonging etoposide dosing to 10 days did not permit further dose intensification, as a time delay to retreatment owing to unrecovered bone marrow rapidly emerged as the DLT. Post-infusion total plasma levels of topotecan declined in a biphasic manner with a terminal half-life of 2.1 +/- 0.3 h. Total body clearance was 13.8 +/- 2.7 l h-1 m-2 with a steady-state volume of distribution of 36.7 +/- 6.2 l m-2. N-desmethyltopotecan, a metabolite of topotecan, was detectable in plasma and urine. Mean maximal concentrations ranged from 0.23 to 0.53 nmol l-1, and were reached at 3.4 +/- 1.0 h after infusion. Maximal etoposide plasma concentrations of 0.75 +/- 0.54 and 1.23 +/- 0.57 micromol l-1 were reached at 2.4 +/- 1.2 and 2.3 +/- 1.0 h after ingestion of 20 and 40 mg respectively. The topotecan area under the plasma concentration vs time curve (AUC) correlated with the percentage decrease in white blood cells (WBC) (r2 = 0.70) and absolute neutrophil count (ANC) (r2 = 0.65). A partial response was observed in a patient with metastatic ovarian carcinoma. A total of 64% of the patients had stable disease for at least 4 months. The recommended dose for use in phase II clinical trials is topotecan 1.0 mg m-2 on days 1-5 and etoposide 40 mg bid on days 6-12 every 4 weeks.

Catheter-related complications in 52 patients treated with continuous infusion of low dose recombinant interleukin-2 via an implanted central venous catheter.

In this study we evaluated the catheter-related complications in 52 patients with advanced melanoma, renal cell cancer or non-Hodgkin's lymphoma treated with continuous infusion of low-dose recombinant interleukin-2 by central venous access (CVA) of the port-a-cath type. We noted a high incidence (55.5%) of catheter infection, defined as positive blood cultures drawn from the CVA in symptomatic or asymptomatic patients. Six infections were noted before rIL-2 treatment was started. Twelve of the 30 documented infections were symptomatic (fever and/or chills), with only four documented bacteraemias. The most frequently cultured microorganism was Staphylococcus epidermidis (73%). Treatment initially consisted of systemic antibiotics via the CVA, but as experience increased, the mostly asymptomatic CVA infections were not treated. In 30% of the documented CVA infections a thrombus at the tip of the catheter was found by radiological contrast examination. Local thrombosis can be effectively treated with constant infusion of low dose streptokinase via the CVA.

Toxicity grading systems. A comparison between the WHO scoring system and the Common Toxicity Criteria when used for nausea and vomiting.

BACKGROUND: The Common Toxicity Criteria adopted by the NCI in the USA for grading toxicity in cancer clinical trials have been compared to the WHO scoring system which is still in use in Europe. PATIENTS & METHODS: Sixty-six patients undergoing emetic chemotherapy at the Netherlands Cancer Institute completed questionnaires, 32 according to the WHO criteria and 34 to the Common Toxicity Criteria, on the severity, frequency and duration of gastro-intestinal toxicity. Their answers were then compared to the scores coded by research nurses and physicians. The nurses coded acute toxicity when the patients were discharged, and the doctors coded overall toxicity when the patients returned for the subsequent course of chemotherapy. To evaluate the coding systems, an estimate was made of the percentage agreement between the patients' answers and the nurses' and doctors' ratings. RESULTS: The percentage agreement of the Common Toxicity Criteria with the patients' own experiences of nausea and vomiting was considerably better than that of the WHO score. The Gamma statistic confirmed this. The Common Toxicity Criteria have now been adopted for grading toxicity in studies of the Early Clinical Trials Group of the EORTC and are recommended for use in other clinical trials.

Intraperitoneal-administered carboplatin in patients with ovarian cancer; influence of a dwell-time on toxicity and response.

PATIENTS AND METHODS: Twenty-one patients with metastatic ovarian cancer with minimal residual disease confined to the peritoneal cavity, were treated with intraperitoneal-administered carboplatin. Carboplatin was added to 2 liters of fluid and given via a Tenckoff-catheter. A dwell-time of 4 hours was allowed. After removal of fluid the amount of recovered carboplatin was determined. RESULTS: It appeared that the median recovery of carboplatin was 25.5% (range 2%-56%). There was a great interpatient variability of carboplatin recovery but it was relatively constant during consecutive courses. CONCLUSIONS: Optimal dosing of intraperitoneal-administered carboplatin with a dwell-time is not possible because of the differences in recovery. This manifested itself in the fact that the absorbed dose, as well as a calculated Area Under the concentration versus time Curve (AUC), were much better related to toxicity than the administered dose.

Phase II study of intermittent continuous infusion of low-dose recombinant interleukin-2 in advanced melanoma and renal cell cancer.

BACKGROUND: Previously we described the immunological and clinical effects of prolonged continuous infusion of low dose rIL-2. In this phase II study we explored the therapeutic efficacy of intermittent continuous infusion of low dose rIL-2. PATIENTS AND METHODS: We selected 15 patients with advanced melanoma and 8 patients with renal cell cancer in good clinical condition, with low tumour burden and no previous systemic treatment. A treatment cycle consisted of infusion of 1.8 x 10(6) IU/m2/24 hrs rIL-2 for 3 weeks on an out-patient basis followed by a 3-week rest. A maximum of four cycles were given. RESULTS: A total of 35 cycles were given. Treatment was well tolerated. Transient hyperthyroidism occurred in 8 patients. No objective responses were noted. We noted a high incidence of central nervous system involvement occurring shortly after treatment. CONCLUSIONS: Intermittent continuous infusion of low dose rIL-2 in advanced melanoma and renal cell cancer is well tolerated but the initial therapeutic results are not promising.

Pharmacokinetics of paclitaxel and metabolites in a randomized comparative study in platinum-pretreated ovarian cancer patients.

PURPOSE: To investigate the pharmacokinetics and pharmacodynamics of paclitaxel in a randomized comparative study with four different treatment arms in patients with platinum-pretreated ovarian carcinoma. PATIENTS AND METHODS: Eighteen patients were entered onto this study in which paclitaxel was administered at a high dose of 175 mg/m2 versus a low dose of 135 mg/m2 on a 3- or 24-hour infusion schedule. A solid-phase extraction technique for sample pretreatment followed by a reverse-phase high-performance liquid chromatographic (HPLC) assay was used for analysis of plasma. RESULTS: Grade 3 neutropenia occurred in all four treatment arms. However, it was more severe on the 24-hour infusion schedule. Paclitaxel concentrations as low as 0.012 mumol/L were measured with the HPLC assay. With this low quantitation threshold, we found the plasma disappearance of paclitaxel to be triphasic, with half-lives t1/2(alpha), t1/2(beta), and t1/2(gamma) mean values for the different treatment arms of 0.19 hours (range, 0.01 to 0.4), 1.9 hours (range, 0.5 to 2.8), and 20.7 hours (range, 4 to 65), respectively. Eleven possible metabolites were found, of which three were identified as taxanes by on-line HPLC-photodiode array (PDA) detection. Investigation of pharmacodynamics shows no clear relationship between the pharmacokinetic parameters area under the plasma concentration time curve (AUC), area under the plasma concentration moment curve (AUMC), maximal plasma concentration (Cmax), clearance, and toxicity. However, a relationship was found between the duration of plasma concentrations above a threshold of 0.1 mumol/L with absolute neutrophil count (ANC) and white blood cell count (WBC). CONCLUSION: Paclitaxel is metabolized, and putative metabolic products can be found in plasma of patients treated with the drug. Our results indicate that myelosuppression can be predicted by the measurement of the duration of plasma concentrations above the threshold of 0.1 mumol/L.

A phase I study of prolonged continuous infusion of low dose recombinant interleukin-2 in melanoma and renal cell cancer. Part I: Clinical aspects.

The optimal schedule for recombinant interleukin-2 (rIL-2) administration is unclear. Because the clinical and immunological effects of prolonged continuous exposure to rIL-2 are unknown, we have conducted a phase I study to assess the toxicity and feasibility of continuous low dose infusion of rIL-2 (EuroCetus) using central venous access with a portable infusion device on an out-patient basis. Twenty-two patients entered the study, 13 with melanoma and nine with renal cell cancer, age range 26-66 years (median 51), performance status less than or equal to 1. They were treated with one of the following doses per m2 per 24 h: 0.18 x 10(6) IU, 0.6 x 10(6) IU, 1.8 x 10(6) IU, 3 x 10(6) IU, 6 x 10(6) IU and 9 x 10(6) IU. Toxicity was evaluable in 20 patients receiving greater than or equal to 3 weeks treatment duration or in whom treatment was discontinued prematurely because of toxicity. Constitutional symptoms consisting of fatigue, malaise and fever up to 40 degrees C without significant organ dysfunction occurred with doses greater than or equal to 1.8 x 10(6) IU m-2. The maximum tolerated dose was 6 x 10(6) IU m-2 24 h-1. In all patients toxicity reached a peak at 3 weeks and resolved thereafter despite continued rIL-2 treatment. Peripheral blood eosinophilia (up to 66% of white blood cell count) followed the same pattern. An infection of the central venous access occurred in 55% of the patients but this was mostly asymptomatic. Thirteen patients were treated greater than or equal to 6 weeks and were evaluable for tumour response. A partial remission occurred in a patient with melanoma with a dose of 1.8 x 10(6) IU rIL-2 m-2 24 h-1.

Chemical and physical stability of etoposide and teniposide in commonly used infusion fluids.

The chemical and physical stabilities of the cytotoxic drugs etoposide and teniposide have been investigated in three different, commonly used, infusion fluids. Chemical stability has been measured by a stability indicating reversed-phase high-performance liquid chromatographic assay with ultraviolet detection. Physical stability was checked by visual inspection and the presence of microparticles was inspected by viewing the admixtures against a white and dark background of a light box equipped with an incandescent lamp and a polarizing filter. Samples were also tested for changes in pH. It is concluded that etoposide and teniposide in 5% dextrose and 0.9% sodium chloride infusion fluids (concentration: 0.4 mg/mL) are chemically stable for at least four days at room temperature. Stability of the drugs is not influenced by the presence of normal room fluorescent light nor by the type of container material used (glass bottles or polyvinyl chloride minibags). Occasional precipitation occurred in etoposide infusion fluids with a concentration higher than 0.4 mg/mL. Teniposide infusion solutions were physically stable at the tested concentrations up to 0.7 mg/mL.

Phase I study of vintriptol, a tryptophan ester of vinblastine.

Vintriptol, a tryptophan ester of vinblastine, is a new vinca alkaloid derivative. Preclinical studies have demonstrated its antitumour activity in a large variety of animal models. In this phase I study, 47 patients with advanced cancer were exposed to escalating doses of vintriptol, starting at 6 mg/m2 and following a modified Fibonacci schedule. The drug was administered as an intravenous push on a weekly schedule. Myelosuppression was the dose-limiting toxicity and the maximum tolerated dose was 45 mg/m2. Other toxicities consisted of mild nausea and vomiting and the occurrence of fever and dryness of the mouth immediately after drug administration. Neurotoxicity, a major side-effect of other vinca alkaloids, was insignificant. 1 partial remission in a patient suffering from colorectal cancer and 1 minor response in a patient with a metastatic tumour of the cutaneous appendagous glands were documented. Pharmacokinetics of vintriptol were evaluated at the highest dose levels. A dose schedule of 40 mg/m2 vintriptol per week is recommended for phase II studies.