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159 Publications visible to you, out of a total of 159
A pharmacokinetic model of filgrastim and pegfilgrastim application in normal mice and those with cyclophosphamide-induced granulocytopaenia
Genetical Statistics and Systems Biology

Abstract (Expand)

OBJECTIVES\backslashr\backslashnRecombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used as treatment for granulocytopaenia during cytotoxic chemotherapy; however, optimal … scheduling of this pharmaceutical is unknown. Biomathematical models can help to pre-select optimal application schedules but precise pharmacokinetic properties of the pharmaceuticals are required at first. In this study, we have aimed to construct a pharmacokinetic model of G-CSF derivatives filgrastim and pegfilgrastim in mice.\backslashr\backslashnMETHODS\backslashr\backslashnHealthy CD-1 mice and those with cyclophosphamide-induced granulocytopaenia were studied after administration of filgrastim and pegfilgrastim in different dosing and timing schedules. Close meshed time series of granulocytes and G-CSF plasma concentrations were determined. An ordinary differential equations model of pharmacokinetics was constructed on the basis of known mechanisms of drug distribution and degradation.\backslashr\backslashnRESULTS\backslashr\backslashnPredictions of the model fit well with all experimental data for both filgrastim and pegfilgrastim. We obtained a unique parameter setting for all experimental scenarios. Differences in pharmacokinetics between filgrastim and pegfilgrastim can be explained by different estimates of model parameters rather than by different model mechanisms. Parameter estimates with respect to distribution and clearance of the drug derivatives are in agreement with qualitative experimental results.\backslashr\backslashnCONCLUSION\backslashr\backslashnDynamics of filgrastim and pegfilgrastim plasma levels can be explained by the same pharmacokinetic model but different model parameters. Beause of a strong clearance mechanism mediated by granulocytes, granulocytotic and granulocytopaenic conditions must be studied simultaneously to construct a reliable model. The pharmacokinetic model will be extended to a murine model of granulopoiesis under chemotherapy and G-CSF application.

Authors: Markus Scholz, Manuela Ackermann, Christoph Engel, Frank Emmrich, Markus Loeffler, Manja Kamprad

Date Published: 1st Dec 2009

Publication Type: Journal article

Pharmacokinetic and pharmacodynamic modelling of the novel human granulocyte colony-stimulating factor derivative Maxy-G34 and pegfilgrastim in rats
Genetical Statistics and Systems Biology

Abstract (Expand)

OBJECTIVES\backslashr\backslashnThis study aims to compare pharmacokinetics and pharmacodynamics of pegfilgrastim, a pharmaceutical recombinant human granulocyte colony-stimulating factor (rhG-CSF), … with that of a newly developed reagent, Maxy-G34. This comparison was performed using rat experiments and biomathematical modelling of granulopoiesis.\backslashr\backslashnMETHODS\backslashr\backslashnHealthy rats and those with cyclophosphamide-induced neutropenia were treated with either pegfilgrastim or Maxy-G34 under various schedules. Time courses of absolute neutrophil count (ANC) and G-CSF serum level were measured and we constructed a combined pharmacokinetic/pharmacodynamic model of both drugs. Neutropenic episodes were assessed by experimental data and model simulations.\backslashr\backslashnRESULTS\backslashr\backslashnBoth Pegfilgrastim and Maxy-G34 showed strong dose-dependent efficacy in reducing neutropenic episodes. However, time courses of ANC and G-CSF serum levels were markedly different. The biomathematical model showed good agreement with these data. We estimated that differences between the two drugs could be explained by lower bioavailability and reduced elimination of Maxy-G34. Based on the data and model interpolations, we estimated that Maxy-G34 is superior in reducing neutropenic episodes. Also, we predicted that G-CSF administration 48 h after cyclophosphamide would be superior to its administration after 2 or 24 h, for both derivatives.\backslashr\backslashnCONCLUSION\backslashr\backslashnMaxy-G34 is a highly potent drug for stimulation of neutrophil production in rats. By our modelling approach, we quantified differences between Maxy-G34 and pegfilgrastim, related to pharmacokinetic parameters. Model simulations can be used to estimate optimal dosing and timing options in the present preclinical rat model.

Authors: Markus Scholz, Christoph Engel, D. Apt, S. L. Sankar, E. Goldstein, Markus Loeffler

Date Published: 1st Dec 2009

Publication Type: Journal article

Common variants in LSP1, 2q35 and 8q24 and breast cancer risk for BRCA1 and BRCA2 mutation carriers
GC-HBOC - German Consortium for Hereditary Breast and Ovarian Cancer

Abstract (Expand)

Genome-wide association studies of breast cancer have identified multiple single nucleotide polymorphisms (SNPs) that are associated with increased breast cancer risks in the general population. In a … previous study, we demonstrated that the minor alleles at three of these SNPs, in FGFR2, TNRC9 and MAP3K1, also confer increased risks of breast cancer for BRCA1 or BRCA2 mutation carriers. Three additional SNPs rs3817198 at LSP1, rs13387042 at 2q35 and rs13281615 at 8q24 have since been reported to be associated with breast cancer in the general population, and in this study we evaluated their association with breast cancer risk in 9442 BRCA1 and 5665 BRCA2 mutation carriers from 33 study centres. The minor allele of rs3817198 was associated with increased breast cancer risk only for BRCA2 mutation carriers [hazard ratio (HR) = 1.16, 95% CI: 1.07-1.25, P-trend = 2.8 x 10(-4)]. The best fit for the association of SNP rs13387042 at 2q35 with breast cancer risk was a dominant model for both BRCA1 and BRCA2 mutation carriers (BRCA1: HR = 1.14, 95% CI: 1.04-1.25, P = 0.0047; BRCA2: HR = 1.18 95% CI: 1.04-1.33, P = 0.0079). SNP rs13281615 at 8q24 was not associated with breast cancer for either BRCA1 or BRCA2 mutation carriers, but the estimated association for BRCA2 mutation carriers (per-allele HR = 1.06, 95% CI: 0.98-1.14) was consistent with odds ratio estimates derived from population-based case-control studies. The LSP1 and 2q35 SNPs appear to interact multiplicatively on breast cancer risk for BRCA2 mutation carriers. There was no evidence that the associations vary by mutation type depending on whether the mutated protein is predicted to be stable or not.

Authors: Antonis C. Antoniou, Olga M. Sinilnikova, Lesley McGuffog, Sue Healey, Heli Nevanlinna, Tuomas Heikkinen, Jacques Simard, Amanda B. Spurdle, Jonathan Beesley, Xiaoqing Chen, Susan L. Neuhausen, Yuan C. Ding, Fergus J. Couch, Xianshu Wang, Zachary Fredericksen, Paolo Peterlongo, Bernard Peissel, Bernardo Bonanni, Alessandra Viel, Loris Bernard, Paolo Radice, Csilla I. Szabo, Lenka Foretova, Michal Zikan, Kathleen Claes, Mark H. Greene, Phuong L. Mai, Gad Rennert, Flavio Lejbkowicz, Irene L. Andrulis, Hilmi Ozcelik, Gord Glendon, Anne-Marie Gerdes, Mads Thomassen, Lone Sunde, Maria A. Caligo, Yael Laitman, Tair Kontorovich, Shimrit Cohen, Bella Kaufman, Efrat Dagan, Ruth Gershoni Baruch, Eitan Friedman, Katja Harbst, Gisela Barbany-Bustinza, Johanna Rantala, Hans Ehrencrona, Per Karlsson, Susan M. Domchek, Katherine L. Nathanson, Ana Osorio, Ignacio Blanco, Adriana Lasa, Javier Benítez, Ute Hamann, Frans B. L. Hogervorst, Matti A. Rookus, J. Margriet Collee, Peter Devilee, Marjolijn J. Ligtenberg, Rob B. van der Luijt, Cora M. Aalfs, Quinten Waisfisz, Juul Wijnen, Cornelis E. P. van Roozendaal, Susan Peock, Margaret Cook, Debra Frost, Clare Oliver, Radka Platte, D. Gareth Evans, Fiona Lalloo, Rosalind Eeles, Louise Izatt, Rosemarie Davidson, Carol Chu, Diana Eccles, Trevor Cole, Shirley Hodgson, Andrew K. Godwin, Dominique Stoppa-Lyonnet, Bruno Buecher, Mélanie Léoné, Brigitte Bressac-de Paillerets, Audrey Remenieras, Olivier Caron, Gilbert M. Lenoir, Nicolas Sevenet, Michel Longy, Sandra Fert Ferrer, Fabienne Prieur, David Goldgar, Alexander Miron, Esther M. John, Saundra S. Buys, Mary B. Daly, John L. Hopper, Mary Beth Terry, Yosuf Yassin, Christian Singer, Daphne Gschwantler-Kaulich, Christine Staudigl, Thomas v. O. Hansen, Rosa Bjork Barkardottir, Tomas Kirchhoff, Prodipto Pal, Kristi Kosarin, Kenneth Offit, Marion Piedmonte, Gustavo C. Rodriguez, Katie Wakeley, John F. Boggess, Jack Basil, Peter E. Schwartz, Stephanie V. Blank, Amanda E. Toland, Marco Montagna, Cinzia Casella, Evgeny N. Imyanitov, Anna Allavena, Rita K. Schmutzler, Beatrix Versmold, Christoph Engel, Alfons Meindl, Nina Ditsch, Norbert Arnold, Dieter Niederacher, Helmut Deissler, Britta Fiebig, Christian Suttner, Ines Schönbuchner, Dorothea Gadzicki, Trinidad Caldes, Miguel de La Hoya, Karen A. Pooley, Douglas F. Easton, Georgia Chenevix-Trench

Date Published: 15th Nov 2009

Publication Type: Journal article

Human Diseases: hereditary breast ovarian cancer syndrome

Polymorphisms in BRCA2 resulting in aberrant codon-usage and their analysis on familial breast cancer risk
GC-HBOC - German Consortium for Hereditary Breast and Ovarian Cancer

Abstract (Expand)

Mutations in BRCA1 and BRCA2 are associated with increased breast cancer risk. While numerous non-synonymous SNPs in BRCA1/2 have been investigated for breast cancer risk, the impact of synonymous SNPs … has not been studied so far. Recently, it has been reported that synonymous SNPs leading to an aberration from the preferred codon-usage can have functional effects and consequently be associated with disease. This motivated us to search for SNPs with the tendency to differential codon-usage in BRCA1/BRCA2. Based on defined criteria, two codon-usage-changing variants, Ser455Ser (1365A \textgreater G) and Ser2414Ser (7242A \textgreater G), were detected in BRCA2, whereas no such variant could be identified in BRCA1. We investigated the impact of these variants on breast cancer risk in a large case-control study. However, both SNPs, BRCA2 Ser2414Ser (7242A \textgreater G) and Ser455Ser (1365A \textgreater G), showed no association with breast cancer risk. This indicates that these codon-usage-changing SNPs have no major impact on familial breast cancer risk.

Authors: Rongxi Yang, Bowang Chen, Kari Hemminki, Barbara Wappenschmidt, Christoph Engel, Christian Sutter, Nina Ditsch, Bernhard H. F. Weber, Dieter Niederacher, Norbert Arnold, Alfons Meindl, Claus R. Bartram, Rita K. Schmutzler, Barbara Burwinkel

Date Published: 1st Nov 2009

Publication Type: Journal article

Human Diseases: hereditary breast ovarian cancer syndrome

The TP53 Arg72Pro and MDM2 309GT polymorphisms are not associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers
GC-HBOC - German Consortium for Hereditary Breast and Ovarian Cancer

Abstract (Expand)

BACKGROUND The TP53 pathway, in which TP53 and its negative regulator MDM2 are the central elements, has an important role in carcinogenesis, particularly in BRCA1- and BRCA2-mediated carcinogenesis. …. A single nucleotide polymorphism (SNP) in the promoter region of MDM2 (309T\textgreaterG, rs2279744) and a coding SNP of TP53 (Arg72Pro, rs1042522) have been shown to be of functional significance. METHODS To investigate whether these SNPs modify breast cancer risk for BRCA1 and BRCA2 mutation carriers, we pooled genotype data on the TP53 Arg72Pro SNP in 7011 mutation carriers and on the MDM2 309T\textgreaterG SNP in 2222 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Data were analysed using a Cox proportional hazards model within a retrospective likelihood framework. RESULTS No association was found between these SNPs and breast cancer risk for BRCA1 (TP53: per-allele hazard ratio (HR)=1.01, 95% confidence interval (CI): 0.93-1.10, P(trend)=0.77; MDM2: HR=0.96, 95%CI: 0.84-1.09, P(trend)=0.54) or for BRCA2 mutation carriers (TP53: HR=0.99, 95%CI: 0.87-1.12, P(trend)=0.83; MDM2: HR=0.98, 95%CI: 0.80-1.21, P(trend)=0.88). We also evaluated the potential combined effects of both SNPs on breast cancer risk, however, none of their combined genotypes showed any evidence of association. CONCLUSION There was no evidence that TP53 Arg72Pro or MDM2 309T\textgreaterG, either singly or in combination, influence breast cancer risk in BRCA1 or BRCA2 mutation carriers.

Authors: O. M. Sinilnikova, A. C. Antoniou, J. Simard, S. Healey, M. Léoné, D. Sinnett, A. B. Spurdle, J. Beesley, X. Chen, M. H. Greene, J. T. Loud, F. Lejbkowicz, G. Rennert, S. Dishon, I. L. Andrulis, S. M. Domchek, K. L. Nathanson, S. Manoukian, P. Radice, I. Konstantopoulou, I. Blanco, A. L. Laborde, M. Durán, A. Osorio, J. Benitez, U. Hamann, F. B. L. Hogervorst, T. A. M. van Os, H. J. P. Gille, S. Peock, M. Cook, C. Luccarini, D. G. Evans, F. Lalloo, R. Eeles, G. Pichert, R. Davidson, T. Cole, J. Cook, J. Paterson, C. Brewer, D. J. Hughes, I. Coupier, S. Giraud, F. Coulet, C. Colas, F. Soubrier, E. Rouleau, I. Bièche, R. Lidereau, L. Demange, C. Nogues, H. T. Lynch, R. K. Schmutzler, B. Versmold, C. Engel, A. Meindl, N. Arnold, C. Sutter, H. Deissler, D. Schaefer, U. G. Froster, K. Aittomäki, H. Nevanlinna, L. McGuffog, D. F. Easton, G. Chenevix-Trench, D. Stoppa-Lyonnet

Date Published: 1st Oct 2009

Publication Type: Journal article

Human Diseases: hereditary breast ovarian cancer syndrome

No association of TGFB1 L10P genotypes and breast cancer risk in BRCA1 and BRCA2 mutation carriers: a multi-center cohort study
GC-HBOC - German Consortium for Hereditary Breast and Ovarian Cancer

Abstract (Expand)

BACKGROUND The transforming growth factor beta-1 gene (TGFB1) is a plausible candidate for breast cancer susceptibility. The L10P variant of TGFB1 is associated with higher circulating levels and …d secretion of TGF-beta, and recent large-scale studies suggest strongly that this variant is associated with breast cancer risk in the general population. METHODS To evaluate whether TGFB1 L10P also modifies the risk of breast cancer in BRCA1 or BRCA2 mutation carriers, we undertook a multi-center study of 3,442 BRCA1 and 2,095 BRCA2 mutation carriers. RESULTS We found no evidence of association between TGFB1 L10P and breast cancer risk in either BRCA1 or BRCA2 mutation carriers. The per-allele HR for the L10P variant was 1.01 (95%CI: 0.92-1.11) in BRCA1 carriers and 0.92 (95%CI: 0.81-1.04) in BRCA2 mutation carriers. CONCLUSIONS These results do not support the hypothesis that TGFB1 L10P genotypes modify the risk of breast cancer in BRCA1 or BRCA2 mutation carriers.

Authors: Timothy R. Rebbeck, Antonis C. Antoniou, Trinidad Caldes Llopis, Heli Nevanlinna, Kristiina Aittomäki, Jacques Simard, Amanda B. Spurdle, Fergus J. Couch, Lutecia H. Mateus Pereira, Mark H. Greene, Irene L. Andrulis, Boris Pasche, Virginia Kaklamani, Ute Hamann, Csilla Szabo, Susan Peock, Margaret Cook, Patricia A. Harrington, Alan Donaldson, Allison M. Male, Carol Anne Gardiner, Helen Gregory, Lucy E. Side, Anne C. Robinson, Louise Emmerson, Ian Ellis, Jean-Philippe Peyrat, Joëlle Fournier, Philippe Vennin, Claude Adenis, Danièle Muller, Jean-Pierre Fricker, Michel Longy, Olga M. Sinilnikova, Dominique Stoppa-Lyonnet, Rita K. Schmutzler, Beatrix Versmold, Christoph Engel, Alfons Meindl, Karin Kast, Dieter Schaefer, Ursula G. Froster, Georgia Chenevix-Trench, Douglas F. Easton

Date Published: 1st May 2009

Publication Type: Journal article

Human Diseases: hereditary breast ovarian cancer syndrome

Association of hormone receptor status with grading, age of onset, and tumor size in BRCA1-associated breast cancer
GC-HBOC - German Consortium for Hereditary Breast and Ovarian Cancer

Abstract (Expand)

BRCA1-associated breast cancer frequently presents with estrogen-receptor (ERalpha) and progesterone-receptor (PR) negativity, grade 3, and early onset. In contrast, in BRCA1-deficient mice, ERalpha … is highly expressed in early tumorigenesis. In a retrospective cohort study on 587 breast cancer patients with deleterious BRCA1 mutations, the correlation of ER, PR status, grading, age of onset, and tumor size was investigated. ERalpha and PR expression decreased from 62% in ductal carcinoma in situ (DCIS) to 20% and 16% in pT3, respectively (p value for ER 0.025 and PR 0.035, Fisher’s exact test). The percentage of grade 1/2 tumors decreased from 44% in DCIS to 17% in pT3 (p value 0.074). Moreover, ER/PR positivity increased with increasing age. Our data suggest that early stage BRCA1-associated breast cancers are more frequently ERalpha and PR positive and low grade than advanced stages.

Authors: M. Graeser, K. Bosse, M. Brosig, C. Engel, R. K. Schmutzler

Date Published: 1st May 2009

Publication Type: Journal article

Human Diseases: hereditary breast ovarian cancer syndrome

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