Identification and synthesis of (Z)-3'-hydroxy clomiphene as a new potential doping-relevant metabolite of clomiphene.

A recent study addressed the possibility of unintentional ingestion of clomiphene through residues in chicken eggs. The method developed here helped distinguish between microdose intake of (E/Z)-clomiphene citrate and consumption of clomiphene-containing eggs by the urinary pattern of four mono-hydroxylated clomiphene metabolites. However, reanalyses of doping-control samples, which showed an adverse analytical finding for clomiphene, revealed a hydroxy clomiphene (HC) isomer that was not found after microdose intake or after consumption of clomiphene-containing eggs and could not be assigned to any of the available reference compounds. The aim of the present follow-up study was to identify this HC isomer and to characterize this metabolite with respect to its potential properties as long-term metabolite in doping controls. METHODS: (E/Z)-3'-HC and (E/Z)-4'-HC were synthesized involving the McMurry reaction. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and optimized after a derivatization step with dansyl chloride to separate eight HC isomers. Using this method, urine samples from a controlled clomiphene administration study were analyzed, in which male study participants received therapeutic doses of clomiphene for 30 days and collected urine samples for up to 8 months. Thus, isomer-specific HC elimination profiles could be monitored. RESULTS: The metabolite previously found in doping-control samples was identified as (Z)-3'-HC. The elimination profiles of the different HCs confirmed previous results, with (Z)-3-HC being the most abundant urinary hydroxy metabolite shortly after administration. A new finding was that the data suggest that (Z)-3'-HC is excreted at higher relative concentrations only several weeks after drug intake. CONCLUSION: These findings might be of particular importance in sport drug testing as they can assist in the decision-making process to distinguish between intentional doping and inadvertent exposure to clomiphene via food contamination.

The formation of estrogen-like tamoxifen metabolites and their influence on enzyme activity and gene expression of ADME genes.

Tamoxifen, a standard therapy for breast cancer, is metabolized to compounds with anti-estrogenic as well as estrogen-like action at the estrogen receptor. Little is known about the formation of estrogen-like metabolites and their biological impact. Thus, we characterized the estrogen-like metabolites tamoxifen bisphenol and metabolite E for their metabolic pathway and their influence on cytochrome P450 activity and ADME gene expression. The formation of tamoxifen bisphenol and metabolite E was studied in human liver microsomes and Supersomes™. Cellular metabolism and impact on CYP enzymes was analyzed in upcyte® hepatocytes. The influence of 5 µM of tamoxifen, anti-estrogenic and estrogen-like metabolites on CYP activity was measured by HPLC MS/MS and on ADME gene expression using RT-PCR analyses. Metabolite E was formed from tamoxifen by CYP2C19, 3A and 1A2 and from desmethyltamoxifen by CYP2D6, 1A2 and 3A. Tamoxifen bisphenol was mainly formed from (E)- and (Z)-metabolite E by CYP2B6 and CYP2C19, respectively. Regarding phase II metabolism, UGT2B7, 1A8 and 1A3 showed highest activity in glucuronidation of tamoxifen bisphenol and metabolite E. Anti-estrogenic metabolites (Z)-4-hydroxytamoxifen, (Z)-endoxifen and (Z)-norendoxifen inhibited the activity of CYP2C enzymes while tamoxifen bisphenol consistently induced CYPs similar to rifampicin and phenobarbital. On the transcript level, highest induction up to 5.6-fold was observed for CYP3A4 by tamoxifen, (Z)-4-hydroxytamoxifen, tamoxifen bisphenol and (E)-metabolite E. Estrogen-like tamoxifen metabolites are formed in CYP-dependent reactions and are further metabolized by glucuronidation. The induction of CYP activity by tamoxifen bisphenol and the inhibition of CYP2C enzymes by anti-estrogenic metabolites may lead to drug-drug-interactions.

Comprehensive Metabolomic and Lipidomic Profiling of Human Kidney Tissue: A Platform Comparison.

Metabolite profiling of tissue samples is a promising approach for the characterization of cancer pathways and tumor classification based on metabolic features. Here, we present an analytical method for nontargeted metabolomics of kidney tissue. Capitalizing on different chemical properties of metabolites allowed us to extract a broad range of molecules covering small polar molecules and less polar lipid classes that were analyzed by LC-QTOF-MS after HILIC and RP chromatographic separation, respectively. More than 1000 features could be reproducibly extracted and analyzed (CV < 30%) in porcine and human kidney tissue, which were used as surrogate matrices for method development. To further assess assay performance, cross-validation of the nontargeted metabolomics platform to a targeted metabolomics approach was carried out. Strikingly, from 102 metabolites that could be detected on both platforms, the majority (>90%) revealed Spearman's correlation coefficients ≥0.3, indicating that quantitative results from the nontargeted assay are largely comparable to data derived from classical targeted assays. Finally, as proof of concept, the method was applied to human kidney tissue where a clear differentiation between kidney cancer and nontumorous material could be demonstrated on the basis of unsupervised statistical analysis.

A Temperature of 40 °C Appears to be a Critical Threshold for Potentiating Cytotoxic Chemotherapy In Vitro and in Peritoneal Carcinomatosis Patients Undergoing HIPEC.

BACKGROUND: Hyperthermic intraperitoneal chemotherapy (HIPEC) following cytoreductive surgery is a radical but effective treatment option for patients with peritoneal carcinomatosis (PC). Unfortunately, a standardized HIPEC protocol is missing impeding systematic comparisons with regard to minimal effective temperatures. OBJECTIVE: The purpose of the present study was to systematically analyse the precise minimal temperature needed for potentiation of chemotherapy effects in vitro and for patient survival. METHODS: We established a cell line-based model to mimic HIPEC conditions used in clinical practice, and evaluated intracellular drug concentrations and long-term survival using different temperatures ranging from 38 to 42 °C combined with cisplatin or doxorubicin. In parallel, we evaluated the temperature reached in the clinical setting by measuring inflow and outflow, as well as in two locations in the peritoneal cavity in 34 patients. Finally, we determined the influence of different HIPEC temperatures on survival. RESULTS: Long-term survival of cells treated with either cisplatin or doxorubicin was further improved only at temperatures above 40 °C. In patients, during HIPEC, constant temperatures were reached after 10 min in the peritoneal cavity. A temperature above 40 °C for at least 40 min was achieved in 68 % of patients over the 60 min duration of HIPEC. Importantly, we observed a significantly enhanced overall survival (OS) and progression-free survival (PFS) in those patients reaching temperatures above 40 °C. CONCLUSIONS: Hyperthermia significantly potentiated the chemotherapy effects only at temperatures above 40 °C in vitro. Importantly, this temperature threshold was also critical for OS and PFS of PC patients.

Highly sensitive simultaneous quantification of estrogenic tamoxifen metabolites and steroid hormones by LC-MS/MS.

Tamoxifen is a mainstay in the treatment of estrogen receptor-positive breast cancer and is metabolized to more than 30 different compounds. Little is known about in vivo concentrations of estrogenic metabolites E-metabolite E, Z-metabolite E, and bisphenol and their relevance for tamoxifen efficacy. Therefore, we developed a highly sensitive HPLC-ESI-MS/MS quantification method for tamoxifen metabolites bisphenol, E-metabolite E, and Z-metabolite E as well as for the sex steroid hormones estradiol, estrone, testosterone, androstenedione, and progesterone. Plasma samples were subjected to protein precipitation followed by solid phase extraction. Upon derivatization with 3-[(N-succinimide-1-yl)oxycarbonyl]-1-methylpyridinium iodide, all analytes were separated on a sub-2-µm column with a gradient of acetonitrile in water with 0.1 % of formic acid. Analytes were detected on a triple-quadrupole mass spectrometer with positive electrospray ionization in the multiple reaction monitoring mode. Our method demonstrated high sensitivity, accuracy, and precision. The lower limits of quantification were 12, 8, and 25 pM for bisphenol, E-metabolite E, and Z-metabolite E, respectively, and 4 pM for estradiol and estrogen, 50 pM for testosterone and androstenedione, and 25 pM for progesterone. The method was applied to plasma samples of postmenopausal patients taken at baseline and under tamoxifen therapy. Graphical Abstract Sample preparation and derivatization for highly sensitive quantification of estrogenic tamoxifen metabolites and steroid hormones by HPLC-MS/MS.

Quantitative bile acid profiling by liquid chromatography quadrupole time-of-flight mass spectrometry: monitoring hepatitis B therapy by a novel Na(+)-taurocholate cotransporting polypeptide inhibitor.

A novel analytical approach for the targeted profiling of bile acids (BAs) in human serum/plasma based on liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) is presented. Reversed-phase chromatography enabled the baseline separation of 15 human BA species which could be readily detected by accurate mass analysis in negative ion mode. Blood proteins were removed by methanol precipitation in the presence of deuterium-labeled internal standards which allowed BA quantification in 50 µl plasma/serum. The assay was validated according to FDA guidance achieving quantification limits from 7.8 to 156 nM. Calibration curves prepared in charcoal-stripped serum/plasma showed excellent regression coefficients (R (2) > 0.997) and covered quantities from 7.8 to 10,000 nM depending on the analyzed species. Intra- and inter-day accuracy and precision were below 15 % for all analytes. Apparent extraction recoveries were above 97 %, and ion suppression rates were between 4 and 53 %. Mean BA level in serum/plasma from healthy volunteers ranged from 11 ± 4 nM (tauroursodeoxycholic acid) to 1321 ± 1442 nM (glycochenodeoxycholic acid). As a proof of concept, the assay was applied to plasma samples derived from a clinical phase I study of myrcludex B, a novel first-in-class virus entry inhibitor for the treatment of chronic hepatitis B and D. The results demonstrate that myrcludex-induced inhibition of the hepatic BA transporter Na(+)-taurocholate cotransporting polypeptide (NTCP) significantly affects plasma BA level. These observations provide novel insights into drug-induced metabolic responses and will be indispensable for the assessment of side effects and dose-finding processes during future clinical trials.

Genetic polymorphism of cytochrome P450 2D6 determines oestrogen receptor activity of the major infertility drug clomiphene via its active metabolites.

Clomiphene citrate is the most used drug for the treatment of female infertility, a common condition in western societies and developing countries. Despite dose escalation, up to 30% of women do not respond. Since clomiphene shares structural similarities with tamoxifen, which is predominantly bioactivated by the polymorphic cytochrome P450 (CYP) 2D6, we systematically explored clomiphene metabolism and action in vitro and in vivo by pharmacogenetic, -kinetic and -dynamic investigations. Human liver microsomes were incubated with clomiphene citrate and nine metabolites were identified by mass spectrometry and tested at the oestrogen receptor for their antagonistic capacity. (E)-4-hydroxyclomiphene and (E)-4-hydroxy-N-desethylclomiphene showed strongest inhibition of the oestrogen receptor activity with 50% inhibitory concentrations of 2.5 and 1.4 nm, respectively. CYP2D6 has been identified as the major enzyme involved in their formation using recombinant CYP450 isozymes as confirmed by inhibition experiments with CYP monoclonal antibodies. We correlated the CYP2D6 genotype of 30 human liver donors with the microsomal formation rate of active metabolites and observed a strong gene-dose effect. A healthy female volunteer study confirmed our in vitro data that the CYP2D6 polymorphism substantially determines the formation of the active clomiphene metabolites. Comparison of the C(max) of (E)-4-hydroxyclomiphene and (E)-4-hydroxy-N-desethylclomiphene showed 8 and 12 times lower concentrations in subjects with non-functional CYP2D6 alleles. Our results highlight (E)-4-hydroxyclomiphene and (E)-4-hydroxy-N-desethylclomiphene as the active clomiphene metabolites, the formation of which strongly depends on the polymorphic CYP2D6 enzyme. Our data provide first evidence of a biological rationale for the variability in the response to clomiphene treatment.

Intraperitoneal chemotherapy of peritoneal carcinomatosis using pressurized aerosol as an alternative to liquid solution: first evidence for efficacy.

BACKGROUND: Peritoneal carcinomatosis (PC) is an unmet medical need. Despite recent improvements, systemic chemotherapy has limited efficacy. We report the first application of intraperitoneal chemotherapy as a pressurized aerosol in human patients. METHODS: Three end-stage patients with advanced PC from gastric, appendiceal, and ovarian origin were treated as a compassionate therapy. All patients had received previous systemic chemotherapy. A pressurized aerosol of CO2 loaded with doxorubicin 1.5 mg/m(2) and cisplatin 7.5 mg/m(2) (pressurized intraperitoneal aerosol chemotherapy, PIPAC) was applied into the abdomen for 30 min at a pressure of 12 mmHg and a temperature of 37 °C. RESULTS: No side-effects >2 CTCAE were observed, and the procedures were well tolerated. Early hospital discharge was possible (days 2-5). Nuclear presence of doxorubicin was documented throughout the peritoneum, reaching high local concentration (≤4.1 µmol/g) and plasma concentration was low (4.0-6.2 ng/ml). PIPAC created no significant adhesions, could be repeated, and was applied 6×, 4×, and 2×. Two patients showed a complete and one a partial histological remission. Mean survival after the first PIPAC was 288 days. One patient is alive after 567 days. CONCLUSIONS: PIPAC shows superior pharmacological properties with high local concentration and low systemic exposure. PIPAC can induce regression of PC in chemoresistant tumors, using 10% of a usual systemic dose.

A new [2H]-labelled α-trichloroimidate glucuronic ester for the synthesis of deuterated drug conjugates.

A new reaction pathway for the synthesis of a [(2)H]-labelled trichloroacetimidate precursor for the preparation of glucuronides is described. Therewith, stable isotope-labelled drug glucuronides become accessible on a preparative scale, which can further be used as internal standards for quantitative analysis.

Nonlinear Mixed-Effects Model of Z-Endoxifen Concentrations in Tamoxifen-Treated Patients from the CEPAM Cohort.

Tamoxifen is widely used in patients with hormone receptor-positive breast cancer. The polymorphic enzyme CYP2D6 is primarily responsible for metabolic activation of tamoxifen, resulting in substantial interindividual variability of plasma concentrations of its most important metabolite, Z-endoxifen. The Z-endoxifen concentration thresholds below which tamoxifen treatment is less efficacious have been proposed but not validated, and prospective trials of individualized tamoxifen treatment to achieve Z-endoxifen concentration thresholds are considered infeasible. Therefore, we aim to validate the association between Z-endoxifen concentration and tamoxifen treatment outcomes, and identify a Z-endoxifen concentration threshold of tamoxifen efficacy, using pharmacometric modeling and simulation. As a first step, the CYP2D6 Endoxifen Percentage Activity Model (CEPAM) cohort was created by pooling data from 28 clinical studies (> 7,000 patients) with measured endoxifen plasma concentrations. After cleaning, data from 6,083 patients were used to develop a nonlinear mixed-effect (NLME) model for tamoxifen and Z-endoxifen pharmacokinetics that includes a conversion factor to allow inclusion of studies that measured total endoxifen but not Z-endoxifen. The final parent-metabolite NLME model confirmed the primary role of CYP2D6, and contributions from body weight, CYP2C9 phenotype, and co-medication with CYP2D6 inhibitors, on Z-endoxifen pharmacokinetics. Future work will use the model to simulate Z-endoxifen concentrations in patients receiving single agent tamoxifen treatment within large prospective clinical trials with long-term survival to identify the Z-endoxifen concentration threshold below which tamoxifen is less efficacious. Identification of this concentration threshold would allow personalized tamoxifen treatment to improve outcomes in patients with hormone receptor-positive breast cancer.