Phase I pharmacological study of continuous chronomodulated capecitabine treatment.

PURPOSE: Capecitabine is an oral pre-pro-drug of the anti-cancer drug 5-fluorouracil (5-FU). The biological activity of the 5-FU degrading enzyme, dihydropyrimidine dehydrogenase (DPD), and the target enzyme thymidylate synthase (TS), are subject to circadian rhythmicity in healthy volunteers. The aim of this study was to determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, pharmacokinetics (PK) and pharmacodynamics (PD) of capecitabine therapy adapted to this circadian rhythm (chronomodulated therapy). METHODS: Patients aged ≥18 years with advanced solid tumours potentially benefitting from capecitabine therapy were enrolled. A classical dose escalation 3 + 3 design was applied. Capecitabine was administered daily without interruptions. The daily dose was divided in morning and evening doses that were administered at 9:00 h and 24:00 h, respectively. The ratio of the morning to the evening dose was 3:5 (morning: evening). PK and PD were examined on treatment days 7 and 8. RESULTS: A total of 25 patients were enrolled. The MTD of continuous chronomodulated capecitabine therapy was established at 750/1250 mg/m2/day, and was generally well tolerated. Circadian rhythmicity in the plasma PK of capecitabine, dFCR, dFUR and 5-FU was not demonstrated. TS activity was induced and DPD activity demonstrated circadian rhythmicity during capecitabine treatment. CONCLUSION: The MTD of continuous chronomodulated capecitabine treatment allows for a 20% higher dose intensity compared to the approved regimen (1250 mg/m2 bi-daily on day 1-14 of every 21-day cycle). Chronomodulated treatment with capecitabine is promising and could lead to improved tolerability and efficacy of capecitabine.

P-glycoprotein (MDR1/ABCB1) controls brain accumulation and intestinal disposition of the novel TGF-ß signaling pathway inhibitor galunisertib.

Galunisertib (LY2157299), a promising small-molecule inhibitor of the transforming growth factor-beta (TGF-ß) receptor, is currently in mono- and combination therapy trials for various cancers including glioblastoma, hepatocellular carcinoma and breast cancer. Using genetically modified mouse models, we investigated the roles of the multidrug efflux transporters ABCB1 and ABCG2, the OATP1A/1B uptake transporters and the drug-metabolizing CYP3A complex in galunisertib pharmacokinetics. In vitro, galunisertib was vigorously transported by human ABCB1, and moderately by mouse Abcg2. Orally administered galunisertib (20 mg/kg) was very rapidly absorbed. Galunisertib brain-to-plasma ratios were increased by ~24-fold in Abcb1a/1b-/- and Abcb1a/1b;Abcg2-/- mice compared to wild-type mice, but not in single Abcg2-/- mice, whereas galunisertib oral availability was not markedly affected. However, recovery of galunisertib in the small intestinal lumen was strongly reduced in Abcb1a/1b-/- and Abcb1a/1b;Abcg2-/- mice. Oral coadministration of the ABCB1/ABCG2 inhibitor elacridar boosted galunisertib brain accumulation in wild-type mice to equal the levels seen in Abcb1a/1b;Abcg2-/- mice. Oatp1a/1b deficiency did not alter oral galunisertib pharmacokinetics or liver distribution. Cyp3a-/- mice showed a 1.9-fold higher plasma AUC0-1 hr than wild-type mice, but this difference disappeared over 8 hr. Also, transgenic human CYP3A4 overexpression did not significantly alter oral galunisertib pharmacokinetics. Abcb1 thus markedly restricts galunisertib brain penetration and affects its intestinal disposition, possibly through biliary excretion. Elacridar coadministration could fully inhibit both processes, without causing acute toxicity. Moreover, mouse Cyp3a, but not human CYP3A4, may eliminate galunisertib at high plasma concentrations. These insights may help to guide the further clinical development and application of galunisertib.

Pronounced between-subject and circadian variability in thymidylate synthase and dihydropyrimidine dehydrogenase enzyme activity in human volunteers.

AIMS: The enzymatic activity of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are important for the tolerability and efficacy of the fluoropyrimidine drugs. In the present study, we explored between-subject variability (BSV) and circadian rhythmicity in DPD and TS activity in human volunteers. METHODS: The BSVs in DPD activity (n = 20) in peripheral blood mononuclear cells (PBMCs) and in plasma, measured by means of the dihydrouracil (DHU) and uracil (U) plasma levels and DHU : U ratio (n = 40), and TS activity in PBMCs (n = 19), were examined. Samples were collected every 4 h throughout 1 day for assessment of circadian rhythmicity in DPD and TS activity in PBMCs (n = 12) and DHU : U plasma ratios (n = 23). In addition, the effects of genetic polymorphisms and gene expression on DPD and TS activity were explored. RESULTS: Population mean (± standard deviation) DPD activity in PBMCs and DHU : U plasma ratio were 9.2 (±2.1) nmol mg(-1) h(-1) and 10.6 (±2.4), respectively. Individual TS activity in PBMCs ranged from 0.024 nmol mg(-1) h(-1) to 0.596 nmol mg(-1) h(-1) . Circadian rhythmicity was demonstrated for all phenotype markers. Between 00:30 h and 02:00 h, DPD activity in PBMCs peaked, while the DHU : U plasma ratio and TS activity in PBMCs showed trough activity. Peak-to-trough ratios for DPD and TS activity in PBMCs were 1.69 and 1.62, respectively. For the DHU : U plasma ratio, the peak-to-trough ratio was 1.43. CONCLUSIONS: BSV and circadian variability in DPD and TS activity were demonstrated. Circadian rhythmicity in DPD might be tissue dependent. The results suggested an influence of circadian rhythms on phenotype-guided fluoropyrimidine dosing and supported implications for chronotherapy with high-dose fluoropyrimidine administration during the night.

The effect of complementary and alternative medicines on CYP3A4-mediated metabolism of three different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin, midazolam and docetaxel.

OBJECTIVE: Concomitant use of complementary and alternative medicine (CAM) and anticancer drugs can affect the pharmacokinetics of anticancer drugs by inhibiting the metabolizing enzyme cytochrome P450 3A4 (CYP3A4) (EC 1.14.13.157). Several in vitro studies determined whether CAM can inhibit CYP3A4, but these studies revealed contradictory results. A plausible explanation for these conflicting results is the use only of a single model CYP3A4 substrate in each study. Therefore, the objective was to determine the potential of selected CAM (ß-carotene, Echinacea, garlic, Ginkgo biloba, ginseng, grape seed extract, green tea extract, milk thistle, saw palmetto, valerian, vitamin B6, B12 and C) to inhibit CYP3A4-mediated metabolism of different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin (BFC), midazolam and docetaxel. The effect of CAM on CYP3A4-mediated metabolism of an anticancer drug has never been determined before in vitro, which makes this study unique. The oncolytic CYP3A4 substrate docetaxel was used to establish the predictive value of the model substrates for pharmacokinetic interactions between CAM and anticancer drugs in vitro, and to more closely predict these interactions in vivo. METHODS: The inhibition of CYP3A4-mediated metabolism of 7-benzyloxy-4-trifluoromethyl-coumarin (BFC) by CAM was assessed in Supersomes, using the fluorometric CYP3A4 inhibition assay. In human liver microsomes (HLM) the inhibition of CYP3A4-mediated metabolism of midazolam and docetaxel was determined, using liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). KEY FINDINGS: The results confirmed grape seed and green tea as potent inhibitors and milk thistle as moderate inhibitor of CYP3A4-mediated metabolism of BFC, midazolam and docetaxel. CONCLUSION: Clinical studies are required to determine the clinical relevance of the determined CYP3A4 inhibition by grape seed, green tea and milk thistle.

The effect of St John's wort on the pharmacokinetics of docetaxel.

BACKGROUND AND OBJECTIVE: St John's wort (SJW), a herbal antidepressant, is commonly used by cancer patients, and its component hyperforin is a known inducer of the cytochrome P450 (CYP) isoenzyme 3A4. Here, the potential pharmacokinetic interaction between SJW and the sensitive CYP3A4 substrate docetaxel was investigated. METHODS: In ten evaluable cancer patients, the pharmacokinetics of docetaxel (135 mg administered intravenously over 60 min) were compared before and after 14 days of supplementation with SJW (300 mg extract [Hyperiplant(®)] three times daily). RESULTS: SJW supplementation resulted in a statistically significant decrease in the mean area under the docetaxel plasma concentration-time curve extrapolated to infinity (AUC∞) from 3,035 ± 756 to 2,682 ± 717 ng · h/mL (P = 0.045). Furthermore, docetaxel clearance significantly increased from 47.2 to 53.7 L/h (P = 0.045) after SJW intake. The maximum plasma concentration and elimination half-life of docetaxel were (non-significantly) decreased after SJW supplementation. In addition, the incidence of docetaxel-related toxicities was lower after SJW supplementation. CONCLUSION: These results suggest that concomitant use of docetaxel and the applied SJW product should be avoided to prevent potential undertreatment of cancer patients.

Bioequivalence of Liposome-Entrapped Paclitaxel Easy-To-Use (LEP-ETU) formulation and paclitaxel in polyethoxylated castor oil: a randomized, two-period crossover study in patients with advanced cancer.

BACKGROUND: Preclinical studies comparing paclitaxel formulated with polyethoxylated castor oil with the sonicated formulation of liposome-entrapped paclitaxel (LEP) have demonstrated that LEP was associated with reduced toxicity while maintaining similar efficacy. Preliminary studies on the pharmacokinetics in patients support earlier preclinical data, which suggested that the LEP Easy-to-Use (LEP-ETU) formulation and paclitaxel formulated with castor oil may have comparable pharmacokinetic properties. OBJECTIVES: Our objectives were: (1) to determine bioequivalence of paclitaxel pharmaceutically formulated as LEP-ETU (test) and paclitaxel formulated with castor oil (reference); and (2) to assess the tolerability of LEP-ETU following intravenous administration. METHODS: Patients with advanced cancer were studied in a randomized, 2-period crossover bioequivalence study. Patients received paclitaxel 175 mg/m(2) administered as an intravenous infusion over 180 minutes, either as a single-treatment cycle of the test formulation followed by a single-treatment cycle of the reference formulation, or vice versa. RESULTS: Thirty-two of 58 patients were evaluable and were included in the analysis for bioequivalence. Mean total paclitaxel Cmax values for the test and reference formulations were 4955.0 and 5108.8 ng/mL, respectively. Corresponding AUC0-∞ values were 15,853.8 and 18,550.8 ng·h/mL, respectively. Treatment ratios of the geometric means were 97% (90% CI, 91%-103%) for Cmax and 84% (90% CI, 80%-90%) for AUC0-∞. These results met the required 80% to 125% bioequivalence criteria. The most frequently reported adverse events after LEP-ETU administration were fatigue, alopecia, and myalgia. CONCLUSION: At the studied dose regimen, LEP-ETU showed bioequivalence with paclitaxel formulated with polyethoxylated castor oil.

The effect of Echinacea purpurea on the pharmacokinetics of docetaxel.

AIMS: The herbal medicine Echinacea purpurea (E. purpurea) has been shown to induce cytochrome P450 3A4 (CYP3A4) both in vitro and in humans. This study explored whether E. purpurea affects the pharmacokinetics of the CYP3A4 substrate docetaxel in cancer patients. METHODS: Ten evaluable cancer patients received docetaxel (135 mg, 60 min IV infusion) before intake of a commercially available E. purpurea extract (20 oral drops three times daily) and 3 weeks later after a 14 day supplementation period with E. purpurea. In both cycles, pharmacokinetic parameters of docetaxel were determined. RESULTS: Before and after supplementation with E. purpurea, the mean area under the plasma concentration-time curve of docetaxel was 3278 ± 1086 and 3480 ± 1285 ng ml(-1) h, respectively. This result was statistically not significant. Nonsignificant alterations were also observed for the elimination half-life (from 30.8 ± 19.7 to 25.6 ± 5.9 h, P = 0.56) and maximum plasma concentration of docetaxel (from 2224 ± 609 to 2097 ± 925 ng ml(-1) , P = 0.30). CONCLUSIONS: The multiple treatment of E. purpurea did not significantly alter the pharmacokinetics of docetaxel in this study. The applied E. purpurea product at the recommended dose may be combined safely with docetaxel in cancer patients.

The bioanalysis of the major Echinacea purpurea constituents dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides in human plasma using LC-MS/MS.

Alkylamides are a group of active components of the widely used herb Echinacea purpurea (E. purpurea), which have immunostimulatory and anti-inflammatory effects. For the most abundant alkylamides, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides (DTAI), an LC-MS/MS assay has been developed and validated for quantification in human plasma. This assay will be used to support a clinical interaction study with E. purpurea. A 300 µL plasma aliquot underwent liquid-liquid extraction with diethylether-n-hexane (50:50, v/v). After evaporization and reconstitution in 100 µL of acetonitrile-water (50:50, v/v) 20 µL of sample were injected into the HPLC system. Chromatographic separation was achieved with a Polaris 3 C18-A column (50 mm × 2 mm ID, particle size 3 µm), a flow rate of 0.3 mL/min and isocratic elution with acetonitrile-water (50:50, v/v) containing 0.1% formic acid during the first 5 min. Hereafter, gradient elution was applied for 0.5 min, followed by restoration of the initial isocratic conditions. The total run time was 7.5 min. The assay was validated over a concentration range from 0.01 to 50 ng/mL for DTAI, with a lower limit of quantification of 0.01 ng/mL. Validation results show that DTAI can be accurately and precisely quantified in human plasma. DTAI also demonstrated to be chemically stable under relevant conditions. Finally, the applicability of this assay has been successfully demonstrated by measuring the plasma concentration of DTAI in patients after ingestion of a commercial extract of E. purpurea.

Cytoreductive surgery and intraoperative hyperthermic intraperitoneal chemotherapy with paclitaxel: a clinical and pharmacokinetic study.

BACKGROUND: Intraperitoneal chemotherapy has been recommended as a treatment option for ovarian cancer with peritoneal dissemination. Although its treatment duration is significantly shorter, intraoperative hyperthermic intraperitoneal perfusion chemotherapy (HIPEC) has several advantages over simple intraperitoneal instillation chemotherapy. While platinum compounds have usually been used, only a few have administered paclitaxel during HIPEC. Its large molecular weight suggests a much more favorable pharmacokinetic profile than that of platinum compounds. The pharmacokinetics of paclitaxel during and after HIPEC have not been studied before. METHODS: Thirteen women, mainly with ovarian cancer, underwent cytoreductive surgery and HIPEC with 175 mg/m(2) paclitaxel for 2 h. Morbidity was noted. Peritoneal fluid samples and blood samples were harvested during and until 5 days after HIPEC for pharmacokinetic study in ten patients. RESULTS: No treatment-related mortality was noted. Overall morbidity was 38% (two wound infections, one deep venous thrombosis, two grade 1 thrombopenia, one grade 2 neutropenia, and one grade 3 pancytopenia). Mean maximal intraperitoneal paclitaxel concentration was 101 mg/L, which was an average of 1178 times higher than the peak plasma levels. The peritoneal fluid versus plasma AUC ratio was 1462 for the 2-h HIPEC duration and 366 for the total 5-day study period. Cytotoxic drug concentrations were detected in peritoneal fluid for a mean period of 2.7 days, despite drainage of the drug solution after 2 h of treatment. CONCLUSIONS: HIPEC with paclitaxel following cytoreductive surgery is feasible, relatively safe, and associated with a highly favorable pharmacokinetic profile, despite its short treatment duration. Larger studies with a more homogenous patient cohort and adequate follow-up should be performed to demonstrate its efficacy.

Enhanced resolution triple-quadrupole mass spectrometry for ultra-sensitive and quantitative analysis of the investigational anticancer agent EO9 (apaziquone) and its metabolite EO5a in human and dog plasma to support (pre)-clinical studies of EOquin given intravesically.

A highly sensitive and selective liquid chromatography/tandem mass spectrometric (LC/MS/MS) method was developed to quantify the experimental anticancer agent EO9 and its metabolite EO5a in biological matrices. A 200-microL aliquot of human/dog plasma was spiked with a mixture of deuterated internal standards EO9-d3 and EO5a-d4 and extracted with 1.25 mL of ethyl acetate. Dried extracts were reconstituted in 0.1 M ammonium acetate/methanol (7:3, v/v) and 20-microL volumes were injected onto the LC system. Separation was achieved on a 150 x 2.1 mm C18 column using an alkaline eluent (1 mM ammonium hydroxide/methanol (gradient system)). The detection was performed by a Finnigan TSQ Quantum Ultra equipped with an electrospray ionization source operated in positive mode and enhanced mass resolution capability. It demonstrated improved sensitivity with a factor 10-20 for EO9 and EO5a over a 3-decades dynamic range, with acceptable accuracy and precision, when compared with the previously described assay for EO9 and EO5a, developed by our group, using an API 2000. The assay quantifies a range from 0.5 to 500 ng/mL for EO9 and EO5a using 200-microL human plasma and dog samples. The described mass resolution method was successfully applied for the evaluation of the pharmacokinetic profile of EO9 and its metabolite EO5a in human and dog plasma.

Treatment of ovarian cancer using intraperitoneal chemotherapy with taxanes: from laboratory bench to bedside.

The combination of a taxane, paclitaxel or docetaxel, and a platinum compound has become the systemic chemotherapy of choice for primary ovarian cancer and has demonstrated high efficacy. However, ultimately most patients will die from this disease. Hence, there is a need for even more effective systemic chemotherapy or different treatment strategies. Intraperitoneal chemotherapy with taxanes is such an alternative treatment option. Ovarian cancer is theoretically an attractive malignancy for this regional treatment, because the disease remains largely confined to the peritoneal cavity. The choice of taxanes for this kind of chemotherapy is rational, because of its high activity against ovarian cancer cells and expected favourable pharmacokinetics because of limited absorption from the peritoneal cavity due to their large molecular weight and first-pass effect in the liver. In animal model and human pharmacokinetic studies, very high intraperitoneal drug concentrations and exposure and high peritoneal tumour concentrations were achieved, while systemic drug levels were low. The combination of intraperitoneal chemotherapy with hyperthermia enhances the penetration and cytotoxic activity of many drugs. Although data concerning thermal enhancement of taxane cytotoxicity are inconsistent, experimental studies show that at high locoregional concentrations there seems to be such an effect. Recently, feasibility and efficacy of this treatment have evidently been demonstrated in various clinical studies. A large randomized trial revealed improvement of outcome by intraperitoneal instillation chemotherapy with paclitaxel and cisplatin as first-line treatment. Moreover, promising results have been observed after intraoperative hyperthermic intraperitoneal chemotherapy with docetaxel for recurrent disease.

Pharmacokinetic study of docetaxel in intraoperative hyperthermic i.p. chemotherapy for ovarian cancer.

The purpose of this study was to evaluate the pharmacokinetics and toxicity of docetaxel in continuous hyperthermic perfusion peritoneal chemotherapy (CHPPC) after cytoreductive surgery for peritoneal involvement of gynecological malignancies, mainly ovarian cancer. Eighteen patients, with a mean age of 64 years (range 51-80), underwent cytoreductive surgery and subsequent CHPPC with 75 mg/m2 docetaxel at 41-43 degrees C. One patient was treated twice. In eight cases, peritoneal fluid and blood samples were obtained for pharmacokinetic analysis. Death occurred in two heavily pretreated elderly patients with a high volume i.p. tumor recurrence, probably reflecting poor patient selection (mortality rate 10.5%). Other complications, mainly minor, were recorded after 63% of the procedures. Hematological docetaxel-induced toxicity was limited, while the incidence of wound complications was relatively high and probably caused by the direct exposure of the wound to docetaxel during CHPPC. The maximal i.p. versus plasma concentration ratio ranged from 17 to 95 (average 45), while the i.p. versus systemic exposure ratio varied between 105 and 555 (average 207). We conclude that the use of docetaxel in CHPPC following cytoreductive surgery seems feasible and results in a high i.p. versus systemic exposure ratio. The AUC for the peritoneal cavity is on average 13-27 times higher after i.p. administration of 75 mg/m2 during CHPPC than the AUC achieved in the systemic compartment after i.v. administration of the recommended dose of 100 mg/m2, while docetaxel-induced systemic toxicity is highly limited.