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190 Publications visible to you, out of a total of 190
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

Loss of HLA-DR expression and immunoblastic morphology predict adverse outcome in diffuse large B-cell lymphoma - analyses of cases from two prospective randomized clinical trials.
GLA - German Lymphoma Alliance

Abstract (Expand)

BACKGROUND: Research on prognostically relevant immunohistochemical markers in diffuse large B-cell lymphomas has mostly been performed on retrospectively collected clinical data. This is also true for … immunohistochemical classifiers that are thought to reflect the cell-of-origin subclassification of gene expression studies. In order to obtain deeper insight into the heterogeneous prognosis of diffuse large B-cell lymphomas and to validate a previously published immunohistochemical classifier, we analyzed data from a large set of cases from prospective clinical trials with long-term follow-up. DESIGN AND METHODS: We performed morphological and extensive immunohistochemical analyses in 414 cases of diffuse large B-cell lymphoma from two prospective randomized clinical trials (NHL-B1/B2, Germany). Classification into germinal center and non-germinal center subtypes of B-cell lymphoma was based on the expression pattern of CD10, BCL6, and IRF4. Multivariate analyses were performed adjusting for the factors in the International Prognostic Index. RESULTS: Analyzing 20 different epitopes on tissue microarrays, expression of HLA-DR, presence of CD23(+) follicular dendritic cell meshworks, and monotypic light chain expression emerged as International Prognostic Index-independent markers of superior overall survival. Immunoblastic morphology was found to be related to poor event-free survival. The non-germinal center subtype, according to the three-epitope classifier (CD10, BCL6, and IRF4) did not have prognostic relevance when adjusted for International Prognostic Index factors (relative risk=1.2, p=0.328 for overall survival; and relative risk=1.1, p=0.644 for event-free survival). CONCLUSIONS: The previously reported International Prognostic Index-independent prognostic value of stratification into germinal center/non-germinal center B-cell lymphoma using the expression pattern of CD10, BCL6, and IRF4 was not reproducible in our series. However, other markers and the morphological subtype appear to be of prognostic value.

Authors: H. W. Bernd, M. Ziepert, C. Thorns, W. Klapper, H. H. Wacker, M. Hummel, H. Stein, M. L. Hansmann, G. Ott, A. Rosenwald, H. K. Muller-Hermelink, T. F. Barth, P. Moller, S. B. Cogliatti, M. Pfreundschuh, N. Schmitz, L. Trumper, S. Holler, M. Loffler, A. C. Feller

Date Published: 3rd Nov 2009

Publication Type: Not specified

Human Diseases: diffuse large B-cell lymphoma

Favorable impact of the interleukin-4 receptor allelic variant I75 on the survival of diffuse large B-cell lymphoma patients demonstrated in a large prospective clinical trial.
GLA - German Lymphoma Alliance

Abstract (Expand)

BACKGROUND: Recently published data indicate that host germline variations in immune genes can influence the outcome of lymphoma patients. Interleukin (IL)-4 and IL13 are crucial immune factors and may … influence the course of the disease. Both cytokines signal through the interleukin-4 receptor (IL4R). Therefore, we investigated whether polymorphisms of IL4, IL13 and IL4R genes could predict the outcome of diffuse large B-cell lymphoma (DLBCL) patients. METHODS: In 228 DLBCL samples of the German High-Grade Non-Hodgkin's Lymphoma Study Group, the polymorphisms of IL4 (-524CT, rs2243250), IL13 (-1069CT, rs1800925) and IL4R (I75V, rs1805010; S503P, rs1805015; Q576R, rs1801275) were analyzed and the soluble interleukin-4 receptor (sIL4R) serum level was measured before the start of chemotherapy. RESULTS: Patients harboring IL4R V75 (IL4R(I75V-AG) and IL4R(I75V-GG)) had shorter overall survival (OS) (P = 0.044) and event-free survival (EFS) (P = 0.056) periods compared with I75 carriers (IL4R(I75V-AA)). Multivariate analysis adjusted to the International Prognostic Index revealed a relative risk of 1.9 for carriers of the IL4R V75 (P = 0.011) in relation to OS. DLBCL patients homozygous for the IL4R I75 and low sIL4R serum levels have the most favorable OS and EFS. CONCLUSIONS: These data support the role for host germline gene variations of immunologically important factors like the IL4R I75V gene variation to predict the survival in DLBCL patients.

Authors: N. Schoof, F. von Bonin, S. Zeynalova, M. Ziepert, W. Jung, M. Loeffler, M. Pfreundschuh, L. Trumper, D. Kube

Date Published: 12th Jun 2009

Publication Type: Not specified

Human Diseases: diffuse large B-cell lymphoma

CNS events in elderly patients with aggressive lymphoma treated with modern chemotherapy (CHOP-14) with or without rituximab: an analysis of patients treated in the RICOVER-60 trial of the German High-Grade Non-Hodgkin Lymphoma Study Group (DSHNHL).
GLA - German Lymphoma Alliance

Abstract (Expand)

One thousand two hundred twenty-two patients treated in the Rituximab with CHOP over age 60 years (RICOVER-60) trial were examined for central nervous system (CNS) disease developing during first-line … therapy or after a complete or partial remission had been achieved. Patients received 6 or 8 courses of CHOP (cyclophosphamide, adriamycin, vincristine, prednisone) administered every 2 weeks (CHOP-14) with or without rituximab. CNS prophylaxis for patients with involvement of bone marrow, testes, upper neck, or head consisted of intrathecal (i.th.) methotrexate (days 1 and 5 of first 2 courses). Fifty-eight cases of lymphoma in the CNS were observed (36/609 patients in the CHOP-14 and 22/608 patients in the arituximab-CHOP-14 [R-CHOP-14] arm). The estimated 2-year incidence of CNS disease was 6.9% (confidence interval [CI] 4.5; 9.3) after CHOP-14 and 4.1% (CI 2.3; 5.9) after R-CHOP-14. R-CHOP reduced the relative risk for CNS disease to 0.58 (95% CI 0.3; 1.0, P = .046). Cox regression analysis identified "involvement of more than 1 extranodal site" and "B-symptoms" as significant risk factors for CNS disease. Patients treated with R-CHOP-14 did not show any benefit from i.th. methotrexate. We conclude that elderly patients with aggressive CD20-positive lymphoma show a significantly lower incidence of CNS disease if treated with R-CHOP-14 instead of CHOP-14. Intrathecal methotrexate has no role in preventing CNS disease for patients treated with combined immunochemotherapy (R-CHOP-14)--with the possible exception of patients with testicular involvement.

Authors: V. Boehme, N. Schmitz, S. Zeynalova, M. Loeffler, M. Pfreundschuh

Date Published: 23rd Apr 2009

Publication Type: Not specified

Human Diseases: lymphoma

Effectiveness of cytopenia prophylaxis for different filgrastim and pegfilgrastim schedules in a chemotherapy mouse model
Genetical Statistics and Systems Biology

Abstract (Expand)

OBJECTIVES Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used to treat neutropenia during cytotoxic chemotherapy. The optimal scheduling of rhG-CSF is unknown and can …n hardly be tested in clinical studies due to numerous therapy parameters affecting outcome (chemotherapeutic regimen, rhG-CSF schedules, individual covariables). Motivated by biomathematical model simulations, we aim to investigate different rhG-CSF schedules in a preclinical chemotherapy mouse model. METHODS The time course of hematotoxicity was studied in CD-1 mice after cyclophosphamide (CP) administration. Filgrastim was applied concomitantly in a 2 x 3-factorial design of two dosing options (2 x 20 mug and 4 x 10 mug) and three timing options (directly, one, and two days after CP). Alternatively, a single dose of 40 mug pegfilgrastim was applied at the three timing options. The resulting cytopenia was compared among the schedules. RESULTS Dosing and timing had a significant influence on the effectiveness of filgrastim schedules whereas for pegfilgrastim the timing effect was irrelevant. The best filgrastim and pegfilgrastim schedules exhibited equivalent toxicity. Monocytes dynamics performed analogously to granulocytes. All schedules showed roughly the same lymphotoxicity. CONCLUSION We conclude that effectiveness of filgrastim application depends heavily on its scheduling during chemotherapy. There is an optimum of timing. Dose splitting is better than concentrated applications. Effectiveness of pegfilgrastim is less dependent on timing. OBJECTIVES Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used to treat neutropenia during cytotoxic chemotherapy. The optimal scheduling of rhG-CSF is unknown and can hardly be tested in clinical studies due to numerous therapy parameters affecting outcome (chemotherapeutic regimen, rhG-CSF schedules, individual covariables). Motivated by biomathematical model simulations, we aim to investigate different rhG-CSF schedules in a preclinical chemotherapy mouse model. METHODS The time course of hematotoxicity was studied in CD-1 mice after cyclophosphamide (CP) administration. Filgrastim was applied concomitantly in a 2 x 3-factorial design of two dosing options (2 x 20 mug and 4 x 10 mug) and three timing options (directly, one, and two days after CP). Alternatively, a single dose of 40 mug pegfilgrastim was applied at the three timing options. The resulting cytopenia was compared among the schedules. RESULTS Dosing and timing had a significant influence on the effectiveness of filgrastim schedules whereas for pegfilgrastim the timing effect was irrelevant. The best filgrastim and pegfilgrastim schedules exhibited equivalent toxicity. Monocytes dynamics performed analogously to granulocytes. All schedules showed roughly the same lymphotoxicity. CONCLUSION We conclude that effectiveness of filgrastim application depends heavily on its scheduling during chemotherapy. There is an optimum of timing. Dose splitting is better than concentrated applications. Effectiveness of pegfilgrastim is less dependent on timing.

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

Date Published: 2009

Publication Type: Journal article

Structural aberrations affecting the MYC locus indicate a poor prognosis independent of clinical risk factors in diffuse large B-cell lymphomas treated within randomized trials of the German High-Grade Non-Hodgkin's Lymphoma Study Group (DSHNHL).
GLA - German Lymphoma Alliance

Abstract (Expand)

Recent retrospective studies of heterogeneously treated patients have suggested that chromosomal aberrations of the MYC gene locus indicate an unfavorable prognosis in diffuse large B-cell lymphoma … (DLBCL). Here, we investigated the prognostic impact of MYC aberrations analyzed by interphase fluorescence in situ hybridization in 177 patients with de novo DLBCL treated within the two prospective, randomized trials non-Hodgkin's lymphoma NHL-B1 and NHL-B2. MYC aberrations were detected in 14 DLBCL (7.9%). In a univariate analysis compared with MYC-negative DLBCL, MYC-positive cases showed a significantly shorter overall survival (OS) (P=0.047) and relevantly, though not significantly, shorter event-free survival (EFS) (P=0.062). In a Cox model adjusted for the international prognostic index, the presence of a MYC gene rearrangement was the strongest statistically independent predictor of OS (relative risk 3.4, P=0.004) and EFS (relative risk 2.5, P=0.015), and this also held true when the cell-of-origin signature detected by immunohistochemistry was included in the model.

Authors: W. Klapper, H. Stoecklein, S. Zeynalova, G. Ott, F. Kosari, A. Rosenwald, M. Loeffler, L. Trumper, M. Pfreundschuh, R. Siebert

Date Published: 30th Aug 2008

Publication Type: Not specified

Human Diseases: diffuse large B-cell lymphoma

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