Thomas Mürdter - Academia.edu (original) (raw)

Papers by Thomas Mürdter

Pleura and Peritoneum

Objectives Peritoneal metastasis (PM) is commonly observed in patients with colorectal cancer (CR... more Objectives Peritoneal metastasis (PM) is commonly observed in patients with colorectal cancer (CRC). The outcome of these patients is poor, with an average survival of only six months without therapy, which requires a better understanding of PM biology and new treatment strategies. Methods We established and characterized a human ex vivo peritoneal model to investigate the mechanisms of peritoneal seeding and possible treatment options. For this, CRC cell lines and patient-derived tumor organoids were cultured together with human peritoneum to investigate the invasion of malignant cells and the effects of local chemotherapy. Results Fresh human peritoneum was cultured for up to three weeks in a stainless steel ring system, allowing for survival of all peritoneal structures. Peritoneal cell survival was documented by light microscopy and immunohistochemical staining. Further, immunohistological characterization of the tissue revealed CD3-positive T-lymphocytes and vimentin-positive f...

Molecular and Cellular Biology / Genetics

Clinical Research (Excluding Clinical Trials)

Journal of Clinical Oncology

Anticancer research, Mar 1, 2018

In this retrospective study, we compared breast cancer patients treated with and without mistleto... more In this retrospective study, we compared breast cancer patients treated with and without mistletoe lectin I (ML-I) in addition to standard breast cancer treatment in order to determine a possible effect of this complementary treatment. This study included 18,528 patients with invasive breast cancer. Data on additional ML-I treatments were reported for 164 patients. We developed a "similar case" method with a distance measure retrieved from the beta variable in Cox regression to compare these patients, after stage adjustment, with their non-ML-1 treated counterparts in order to answer three hypotheses concerning overall survival, recurrence free survival and life quality. Raw data analysis of an additional ML-I treatment yielded a worse outcome (p=0.02) for patients with ML treatment, possibly due to a bias inherent in the ML-I-treated patients. Using the "similar case" method (a case-based reasoning approach) we could not confirm this harm for patients using ML-I...

Frontiers in Pharmacology

Purpose: Prediction of impaired tamoxifen (TAM) to endoxifen metabolism may be relevant to improv... more Purpose: Prediction of impaired tamoxifen (TAM) to endoxifen metabolism may be relevant to improve breast cancer treatment, e.g., via TAM dose increase. The polymorphic cytochrome P450 2D6 (CYP2D6) strongly determines an individual's capacity for endoxifen formation, however, CYP2D6 phenotype assignments inferred from genotype widely differ between studies. Thus, we modeled plasma endoxifen predictability depending on variable CYP2D6 genotype groupings. Methods: CYP2D6 diplotype and metabolite plasma concentrations were assessed in 908 pre-and post-menopausal estrogen receptor (ER)-positive, TAM treated early breast cancer patients of Caucasian (N = 678), Middle-Eastern Arab (N = 77), and Asian (N = 153) origin. Robust coefficients of determination (R 2) were estimated for endoxifen (E) or metabolic ratio endoxifen/desmethyl-TAM (E/DMT) as dependent and different CYP2D6 phenotype assignments as independent variables. Allele activity scores (ASs) were modified with respect to a reduced * 10 allele activity. Predictability of endoxifen plasma concentrations above the clinical threshold of 5.9 ng/mL was investigated by receiver operating characteristic (ROC) analysis. Results: CYP2D6 diplotypes (N = 898) were strongly associated with E and E/DMT independent of age (P < 10 −15). Across all ethnicities, 68-82% inter-patient variability of E/DMT was explained by CYP2D6 diplotype, while plasma endoxifen was predictable by 39-58%. The previously used codeine specific phenotype classification showed worse prediction for both endpoints particularly in Asians (median R 2 < 20%; P < 10 −9).

Oncotarget, 2014

Here we study the effects of inducible oncogenic K-Ras (G12V) expression on the polarized morphog... more Here we study the effects of inducible oncogenic K-Ras (G12V) expression on the polarized morphogenesis of colonic epithelial cells. We provide evidence that the autocrine production of heregulins, ligands for the ErbB3 receptor tyrosine kinase, is responsible for the hyperproliferation and aberrant 3D morphogenesis upon oncogenic K-Ras expression. This is in line with results obtained in primary intestinal organoid cultures, in which exogenous heregulin is shown to interfere with normal tissue architecture. Importantly, ErbB3 inhibition and heregulin gene silencing rescued K-Ras G12V-induced features of cell transformation. Together with the increased ErbB3 positivity detected in human high-grade primary colorectal cancers, our findings provide support for an autocrine signaling loop engaged by oncogenic K-Ras involving ErbB3 that contributes to the dedifferentiation of the intestinal epithelium during tumor initiation and progression.

Research article Diclofenac does not interact with codeine metabolism in vivo: A study in healthy... more Research article Diclofenac does not interact with codeine metabolism in vivo: A study in healthy volunteers

European Journal of Cancer Supplements, 2006

SpringerPlus, 2014

To overcome cytochrome P450 2D6 (CYP2D6) mediated tamoxifen resistance in postmenopausal early br... more To overcome cytochrome P450 2D6 (CYP2D6) mediated tamoxifen resistance in postmenopausal early breast cancer, CYP2D6 phenotype-adjusted tamoxifen dosing in patients with impaired CYP2D6 metabolism and/or the application of endoxifen, the most potent tamoxifen metabolite, are alternative treatment options. To elucidate both strategies comprehensively we used a physiologically-based pharmacokinetic (PBPK) modeling approach. Firstly simulation of increasing tamoxifen dosages was performed by a virtual clinical trial including populations of CYP2D6 poor (PM), intermediate (IM) and extensive metabolizers (EM) (N = 8,000). Secondly we performed PBPK-simulations under consideration of tamoxifen use plus concomitant increasing dosages of endoxifen (N = 7,000). Our virtual study demonstrates that dose escalation of tamoxifen in IMs resulted in endoxifen steady-state plasma concentrations similar to CYP2D6 EMs whereas PMs did not reach EM endoxifen levels. Steady-state plasma concentrations o...

Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis

Clinical pharmacology and therapeutics, 2003

Intestinal transport by P-glycoprotein is a recently recognized determinant of drug disposition. ... more Intestinal transport by P-glycoprotein is a recently recognized determinant of drug disposition. However, direct measurements of transporter-mediated drug elimination into isolated segments of human small intestine are lacking. Using a recently developed intestinal perfusion catheter, we perfused in healthy volunteers two 20-cm jejunal segments with and without the P-glycoprotein inhibitor quinidine before and during administration of the P-glycoprotein inducer rifampin (INN, rifampicin). Within 3 hours after intravenous administration of digoxin (1 mg), perfusate samples were collected. We found that 0.45% +/- 0.24% and 0.83% +/- 0.60% of the digoxin dose were eliminated into a jejunal segment and into bile, respectively. Perfusion of the isolated segment with quinidine reduced intestinal digoxin elimination (0.23% +/- 0.08%, P =.031). During rifampin, intestinal digoxin elimination was 0.80 +/- 0.59 (P =.383). Enterocyte P-glycoprotein content correlated with the area under the pl...

BMC clinical pharmacology, Jan 27, 2002

Previously, we have demonstrated a marked inhibition of codeine glucuronidation by diclofenac in ... more Previously, we have demonstrated a marked inhibition of codeine glucuronidation by diclofenac in human liver tissue homogenate. We therefore aimed to investigate whether diclofenac inhibits glucuronidation of codeine also in vivo in healthy volunteers. In a randomised, placebo-controlled, double-blind, cross-over study, 12 healthy volunteers received a singe of 100 mg codeine phosphate plus 50 mg diclofenac sodium or codeine phosphate plus placebo. Over a 36 hour period serum concentrations of codeine and its metabolites as well as urinary excretion were analysed using LC-mass spectrometry. Side effects were recorded and analgesic efficacy was determined using the cold pressor test (0-6 h). A single dose of diclofenac did not alter the formation of codeine-6-glucuronide in healthy volunteers. Metabolic clearance of codeine to morphine was not affected by diclofenac. In terms of side effects, both treatments were well tolerated. Diclofenac did not significantly influence the analgesi...

The Histochemical journal, 2001

Microsomal epoxide hydrolase is a biotransformation enzyme which is involved in the hydrolysis of... more Microsomal epoxide hydrolase is a biotransformation enzyme which is involved in the hydrolysis of various epoxides and epoxide intermediates. In the present study, its distribution was investigated in both normal human tissues and human tumours of different histogenetic origin using immunohistochemical techniques. In normal tissue, epithelial cells were more often and more intensely immunostained than mesenchymal cells. The main epithelial cell types expressing microsomal epoxide hydrolase were hepatocytes, acinus cells of the pancreas, and cells of salivary and adrenal glands. Immunostained cells of mesenchymal origin included monocytes, fibrocytes, fibroblasts, vessel endothelium, muscle cells, and cells of the reproductive system. Three patterns of expression were observed in tumour tissues: (1) moderate or strong in hepatocellular carcinomas, tumours of the adrenal gland, and theca-fibromas of the ovary; (2) inhomogeneous staining pattern of variable intensity in breast cancer, ...

Clinical chemistry, 2001

High-dose busulfan is widely used in conditioning regimens before hematopoietic stem cell transpl... more High-dose busulfan is widely used in conditioning regimens before hematopoietic stem cell transplantation in both adults and children. Large interindividual variability in pharmacokinetics after oral administration has been reported; therefore, therapeutic drug monitoring of busulfan may decrease the incidence of drug-related toxicity (for example, hepatic venoocclusive disease) and may also improve therapeutic efficacy. Busulfan concentrations were quantified using 200 microL of plasma and liquid-liquid extraction with diethyl ether after the addition of [2H8]busulfan as the internal standard. Separation and detection of busulfan and [2H8]busulfan were achieved with a LUNA C8 column (5 microm; 150 x 2 mm i.d.) at 30 degrees C, a HP 1100 liquid chromatography system, and a HP 1100 single-quadrupole mass spectrometer. Busulfan and [2H8]busulfan were detected as ammonium adducts in selected-ion monitoring mode at m/z 264.2 and 272.2, respectively. The calibration curve was linear at 5...

Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 2001

It has been suggested that estrogen receptor-independent high-affinity binding sites for antiestr... more It has been suggested that estrogen receptor-independent high-affinity binding sites for antiestrogens could limit their local bioavailability and response. Microsomal epoxide hydrolase (mEH) was recently shown to be a component of the antiestrogen binding site complex. We investigated whether mEH expression in primary breast tumors is related to disease outcome and to the efficacy of tamoxifen treatment. Expression of mEH was semiquantitatively assessed by immunohistochemistry in sections prepared from archival paraffin blocks of primary breast cancers from 179 patients with a mean follow-up time of 81 months. Expression of mEH was correlated with poor disease outcome in all patients (P: < .01; n = 179) and in patients receiving tamoxifen (P: < .01; n = 78), but not in patients not treated with tamoxifen. Moreover, mEH was an independent prognostic factor by Cox regression analysis. The results of this first exploratory study suggest that mEH expression in primary breast canc...