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Tosca EM, Terranova N, Stuyckens K, Dosne AG, Perera T, Vialard J, King P, Verhulst T, Perez-Ruixo JJ, Magni P, Poggesi I. A translational model-based approach to inform the choice of the dose in phase 1 oncology trials: the case study of erdafitinib. Cancer Chemother Pharmacol 2022; 89:117-128. [PMID: 34786600 DOI: 10.1007/s00280-021-04370-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 10/22/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE Erdafitinib (JNJ-42756493, BALVERSA) is a tyrosine kinase inhibitor indicated for the treatment of advanced urothelial carcinoma. In this work, a translational model-based approach to inform the choice of the doses in phase 1 trials is illustrated. METHODS A pharmacokinetic (PK) model was developed to describe the time course of erdafitinib plasma concentrations in mice and rats. Data from multiple xenograft studies in mice and rats were analyzed using the Simeoni tumor growth inhibition (TGI) model. The model parameters were used to derive a range of erdafitinib exposures that might inform the choice of the doses in oncology phase 1 trials. Conversion of exposures to doses was based on preliminary PK assessments from the first-in human (FIH) study. RESULTS A one-compartment PK disposition model, with linear absorption and dose-dependent clearance, adequately described the PK data in both mice and rats via an allometric scaling approach. The TGI model was able to describe tumor growth dynamics, providing quantitative measurements of erdafitinib antitumor potency in mice and rats. Based on these estimates, ranges of efficacious unbound concentration were identified for erdafitinib in mice (0.642-5.364 μg/L) and rats (0.782-2.565 μg/L). Based on the FIH data, it was possible to transpose exposures into doses and doses of above 4 mg/day provided erdafitinib exposures associated with significant TGI in animals. The findings were in agreement with the results of the FIH trial, in which the first hints of clinical activities were observed at 6 mg. CONCLUSION The successful modeling exercise of erdafitinib preclinical data showed how translational PK-PD modeling might be a tool to help to inform the choice of the doses in FIH studies.
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Affiliation(s)
- E M Tosca
- Dipartimento di Ingegneria Industriale e dell'informazione, Università degli Studi di Pavia, 27100, Pavia, Italy.
| | - N Terranova
- Dipartimento di Ingegneria Industriale e dell'informazione, Università degli Studi di Pavia, 27100, Pavia, Italy
- Merck Institute for Pharmacometrics, Merck Serono S.A. (an affiliate of Merck KGaA, Darmstadt, Germany), Lausanne, Switzerland
| | - K Stuyckens
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - A G Dosne
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - T Perera
- Oncology Discovery, Janssen Research and Development, Beerse, Belgium
| | - J Vialard
- Oncology Discovery, Janssen Research and Development, Beerse, Belgium
| | - P King
- Oncology Discovery, Janssen Research and Development, Beerse, Belgium
| | - T Verhulst
- Oncology Discovery, Janssen Research and Development, Beerse, Belgium
| | - J J Perez-Ruixo
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - P Magni
- Dipartimento di Ingegneria Industriale e dell'informazione, Università degli Studi di Pavia, 27100, Pavia, Italy
| | - I Poggesi
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
- Certara Italia S.p.A, Milano, Italy
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2
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Neyens M, Crauwels HM, Perez-Ruixo JJ, Rossenu S. Population pharmacokinetics of the rilpivirine long-acting formulation after intramuscular dosing in healthy subjects and people living with HIV. J Antimicrob Chemother 2021; 76:3255-3262. [PMID: 34510179 DOI: 10.1093/jac/dkab338] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 08/04/2021] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVES To characterize the population pharmacokinetics of the rilpivirine long-acting (LA) formulation after intramuscular administration. METHODS Rich and sparse rilpivirine plasma concentration data were obtained from seven clinical studies. In total, 18 261 rilpivirine samples were collected from 986 subjects (131 healthy subjects from Phase I studies and 855 people living with HIV from Phase IIb/III studies). Doses ranged from 300 to 1200 mg, as single-dose or multiple-dose regimens (every 4 or 8 weeks). In Phase III studies, an initiation injection of 900 mg followed by continuation injections of 600 mg every 4 weeks was used. Non-linear mixed-effects modelling was performed using NONMEM® software. RESULTS A one-compartment model with linear elimination and two parallel absorption pathways (fast and slow) with sequential zero-first-order processes adequately captured rilpivirine flip-flop pharmacokinetics after intramuscular administration of the LA formulation. The estimated apparent elimination half-life of rilpivirine LA was 200 days. None of the evaluated covariates (age, body weight, BMI, sex, race, health status and needle length) had a clinically relevant impact on rilpivirine pharmacokinetics. CONCLUSIONS The population pharmacokinetic model suitably describes the time course and associated variability of rilpivirine plasma concentrations after rilpivirine LA intramuscular administration. The monthly regimen consists of an oral lead-in period (rilpivirine 25 mg tablets once daily for 4 weeks), followed by an initiation injection of 900 mg rilpivirine LA, then 600 mg rilpivirine LA continuation injections monthly. The absence of a clinically relevant effect of covariates on rilpivirine pharmacokinetics suggests that rilpivirine LA dose adjustments for specific subgroups are not warranted.
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Affiliation(s)
- M Neyens
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - H M Crauwels
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - J J Perez-Ruixo
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
| | - S Rossenu
- Clinical Pharmacology and Pharmacometrics, Janssen Research and Development, Beerse, Belgium
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3
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Perez-Ruixo C, Ackaert O, Ouellet D, Chien C, Uemura H, Olmos D, Mainwaring P, Lee JY, Yu MK, Perez-Ruixo JJ, Smith MR, Small EJ. Efficacy and Safety Exposure-Response Relationships of Apalutamide in Patients with Nonmetastatic Castration-Resistant Prostate Cancer. Clin Cancer Res 2020; 26:4460-4467. [PMID: 32561663 DOI: 10.1158/1078-0432.ccr-20-1041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/14/2020] [Accepted: 06/16/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate the relationship between exposure of apalutamide and its active metabolite, N-desmethyl-apalutamide, and selected clinical efficacy and safety parameters in men with high-risk nonmetastatic castration-resistant prostate cancer. PATIENTS AND METHODS An exploratory exposure-response analysis was undertaken using data from the 1,207 patients (806 apalutamide and 401 placebo) enrolled in the SPARTAN study, including those who had undergone dose reductions and dose interruptions. Univariate and multivariate Cox regression models evaluated the relationships between apalutamide and N-desmethyl-apalutamide exposure, expressed as area under the concentration-time curve at steady state, and metastasis-free survival (MFS). Univariate and multivariate logistic regression models assessed the relationship between apalutamide and N-desmethyl-apalutamide exposure and common treatment-emergent adverse events including fatigue, fall, skin rash, weight loss, and arthralgia. RESULTS A total of 21% of patients in the apalutamide arm experienced dose reductions diminishing the average daily dose to 209 mg instead of 240 mg. Within the relatively narrow exposure range, no statistically significant relationship was found between MFS and apalutamide and N-desmethyl-apalutamide exposure. Within apalutamide-treated subjects, skin rash and weight loss had a statistically significant association with higher apalutamide exposure. CONCLUSIONS The use of apalutamide at the recommended dose of 240 mg once daily provided a similar delay in metastases across the SPARTAN patient population, regardless of exposure. The exploratory exposure-safety analysis supports dose reductions in patients experiencing adverse events.
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Affiliation(s)
| | | | | | - Caly Chien
- Janssen Research & Development, Spring House, Pennsylvania
| | - Hiroji Uemura
- Yokohama City University Medical Center, Yokohama, Japan
| | - David Olmos
- Spanish National Cancer Research Centre (CNIO), Madrid, and Hospitales Universitarios Virgen de la Victoria y Regional, Institute of Biomedical Research in Málaga (IBIMA), Spain
| | - Paul Mainwaring
- Centre for Personalised Nanomedicine, University of Queensland, Brisbane, Australia
| | - Ji Youl Lee
- Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, South Korea
| | - Margaret K Yu
- Janssen Research & Development, Los Angeles, California
| | | | - Matthew R Smith
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Eric J Small
- Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California
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4
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Harrold J, Gisleskog PO, Delor I, Jacqmin P, Perez-Ruixo JJ, Narayanan A, Doshi S, Chow A, Yang BB, Melhem M. Quantification of Radiation Injury on Neutropenia and the Link between Absolute Neutrophil Count Time Course and Overall Survival in Nonhuman Primates Treated with G-CSF. Pharm Res 2020; 37:102. [PMID: 32440783 PMCID: PMC7242243 DOI: 10.1007/s11095-020-02839-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 05/02/2020] [Indexed: 01/09/2023]
Abstract
Purpose To model absolute neutrophil count (ANC) suppression in response to acute radiation (AR) exposure and evaluate ANC time course as a predictor of overall survival (OS) in response to AR exposure with or without treatment with granulocyte colony-stimulating factor in nonhuman primates. Methods Source data were obtained from two pivotal studies conducted in rhesus macaques exposed to 750 cGy of whole body irradiation on day 0 that received either placebo, daily filgrastim, or pegfilgrastim (days 1 and 8 after irradiation). Animals were observed for 60 days with ANC measured every 1 to 2 days. The population model of ANC response to AR and the link between observed ANC time course and OS consisted of three submodels characterizing injury due to radiation, granulopoiesis, and a time-to-event model of OS. Results The ANC response model accurately described the effects of AR exposure on the duration of neutropenia. ANC was a valid surrogate for survival because it explained 76% (95% CI, 41%–97%) and 73.2% (95% CI, 38.7%–99.9%) of the treatment effect for filgrastim and pegfilgrastim, respectively. Conclusion The current model linking radiation injury to neutropenia and ANC time course to OS can be used as a basis for translating these effects to humans. Electronic supplementary material The online version of this article (10.1007/s11095-020-02839-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John Harrold
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA.,Seattle Genetics, Bothell Washington, Massachusetts, USA
| | | | | | | | - Juan Jose Perez-Ruixo
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA.,Janssen Research & Development, Valencia, Spain
| | - Adimoolam Narayanan
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - Sameer Doshi
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - Andrew Chow
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA.,Rigel Pharmaceuticals Inc., South San Francisco, California, USA
| | - Bing-Bing Yang
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - Murad Melhem
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA. .,Vertex Pharmaceuticals, Boston, Massachusetts, USA.
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Harrold J, Gisleskog PO, Perez-Ruixo JJ, Delor I, Chow A, Jacqmin P, Melhem M. Prediction of Survival Benefit of Filgrastim in Adult and Pediatric Patients With Acute Radiation Syndrome. Clin Transl Sci 2020; 13:807-817. [PMID: 32112517 PMCID: PMC7359936 DOI: 10.1111/cts.12777] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/22/2020] [Indexed: 12/30/2022] Open
Abstract
Acute exposure to high doses of radiation leads to severe myelosuppression, but few treatments are currently available to treat hematopoietic syndrome of acute radiation syndrome. Granulocyte colony stimulating factors (e.g., filgrastim) stimulate proliferation of neutrophil precursors and enhance mature neutrophil function. Owing to ethical constraints on conducting clinical research in lethally irradiated humans, we developed a model‐based strategy to integrate preclinical experience in irradiated nonhuman primates (NHPs) and other clinical myelosuppressive conditions to inform filgrastim dosing to treat hematopoietic syndrome of acute radiation syndrome. Models predicting neutrophil counts and overall survival based on drug exposures were calibrated and scaled from NHPs to adult and pediatric human subjects. Several scenarios were examined investigating variations in filgrastim doses, dose frequency, treatment initiation, and duration, as well as the effect of age and radiation dose rate. Model‐based simulations and established safety profiles supported that a subcutaneous filgrastim dose of 10 µg/kg once daily provides a significant survival benefit (50%) over placebo in both adults and children, provided that the treatment is initiated within 1–14 days after radiation exposure and lasts 2–3 weeks. For treatment durations of longer than 3 weeks, filgrastim treatment is not expected to provide significantly greater benefit. This survival benefit is expected to hold for the wide range of radiation doses and dose rates (0.01–1,000 Gy/hours) examined.
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Affiliation(s)
- John Harrold
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | | | - Juan Jose Perez-Ruixo
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | | | - Andrew Chow
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | | | - Murad Melhem
- Department of Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
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Dosne AG, Valade E, Stuyckens K, Li LY, Ouellet D, Perez-Ruixo JJ. Population Pharmacokinetics of Total and Free Erdafitinib in Adult Healthy Volunteers and Cancer Patients: Analysis of Phase 1 and Phase 2 Studies. J Clin Pharmacol 2019; 60:515-527. [PMID: 31742712 DOI: 10.1002/jcph.1547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/14/2019] [Indexed: 11/09/2022]
Abstract
A population pharmacokinetic (PK) model was developed using data pooled from 6 clinical studies (3 in healthy volunteers and 3 in cancer patients) to characterize total and free plasma concentrations of erdafitinib following single- and multiple-dose administration, to understand clinically relevant covariates, and to quantify the inter- and intraindividual variability in erdafitinib PK. An open, linear, 3-compartment disposition model with first-order absorption and a lag time was used to describe the PK profile of total and free erdafitinib plasma concentrations. The PK of erdafitinib were linear and time independent. After oral administration, erdafitinib was rapidly absorbed, with a time to maximum concentration between 2 and 4 hours. In patients, erdafitinib total apparent oral clearance was 0.200 L/h (median free fraction = 0.24%), and the effective terminal half-life of total drug was 76.4 hours. Interindividual variability in PK parameters was moderate for oral clearance and central volume of distribution, and large for absorption rate and peripheral volume of distribution. Sex and renal function were significant covariates on free oral clearance, while weight, sex, and α1 -acid-glycoprotein were significant on oral central volume of distribution. Age, race, and mild hepatic impairment were not significant covariates of erdafitinib exposure. Given that the magnitude of the covariate effects were within 25% of reference values and that the recommended dosing regimen of erdafitinib comprises individual dose up-titrations and reductions based on presence or absence of toxicities, the clinical relevance of the investigated covariates is expected to be limited, and no dose adjustments are warranted.
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Affiliation(s)
- Anne-Gaelle Dosne
- Global Clinical Pharmacology, Janssen Research & Development, Beerse, Belgium
| | - Elodie Valade
- Global Clinical Pharmacology, Janssen Research & Development, Beerse, Belgium
| | - Kim Stuyckens
- Global Clinical Pharmacology, Janssen Research & Development, Beerse, Belgium
| | - Lilian Y Li
- Global Clinical Pharmacology, Janssen Research & Development, Springhouse, Pennsylvania, USA
| | - Daniele Ouellet
- Global Clinical Pharmacology, Janssen Research & Development, Springhouse, Pennsylvania, USA
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7
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Poggesi I, Valenzuela B, Ouellet D, Gonzalez M, Hillewaert V, Baruchel S, Fox E, Perez-Ruixo JJ. Population pharmacokinetics of trabectedin in adolescent patients with cancer. Cancer Chemother Pharmacol 2019; 84:707-717. [PMID: 31286189 DOI: 10.1007/s00280-019-03899-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 06/18/2019] [Indexed: 11/30/2022]
Abstract
PURPOSE To characterize the trabectedin population pharmacokinetics in children and adolescent patients with cancer and compare it with the trabectedin pharmacokinetics in adults. METHODS Plasma concentrations from ten adolescent and three children with cancer (age range 4.0-17.0 years) treated with trabectedin at doses ranging from 1.1 to 1.7 mg/m2, administered as a 24-h continuous intravenous infusion every 3 weeks, were available for the analysis. An external model evaluation was performed to verify whether a previously developed adult population pharmacokinetic model was predictive of the pediatric plasma concentrations of trabectedin. The maximum a posteriori estimation of the individual pharmacokinetic parameters for pediatric patients was conducted, after successful completion of the external evaluation step. The relationships between pharmacokinetic parameters and body size were evaluated. RESULTS External evaluation methods showed no major differences between the adult population and children and adolescent patients of this study. The mean ± standard deviation (SD) of the individual estimated clearance and central volume of distribution in these children/adolescent patients was 36.4 ± 16.1 L/h and 13.2 ± 6.54 L, respectively. These values were similar to the typical values reported for adult patients-37.6 L/h and 13.9 L (for females) and 16.1 L (for males). The median area under the plasma concentration versus time curve (AUC) in children/adolescent patients was 55.1 µg h/L, while in the adult population the median AUC was 61.3 µg h/L, both administered a 1.5 mg/m2 dose regimen with mean (range) BSA for adults = 1.86 (0.90-2.80) vs children/adolescent patients = 1.49 (0.66-2.54). CONCLUSIONS The adult population pharmacokinetic model adequately described the trabectedin plasma concentrations and its variability in the pediatric population of patients involved in this assessment that mostly comprised adolescents. The trabectedin systemic exposure achieved in this population was comparable (within 12%) to the exposure obtained in adult population when the same dose, expressed in mg/m2, was administered.
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Affiliation(s)
- Italo Poggesi
- Janssen-Cilag, Via M. Buonarroti, 23, Cologno Monzese, MI, 20093, Italy.
| | - Belén Valenzuela
- SGS Exprimo, NV, Mechelen, Belgium.,Janssen Research and Development, Beerse, Belgium
| | | | | | | | - Sylvain Baruchel
- The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Elizabeth Fox
- The Children's Hospital of Philadelphia, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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8
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Chen P, Olsson Gisleskog P, Perez-Ruixo JJ, Xiao J, Wilkins J, Narayanan A, Gibbs JP, Melhem M. Population Pharmacokinetics and Pharmacodynamics of the Calcimimetic Etelcalcetide in Chronic Kidney Disease and Secondary Hyperparathyroidism Receiving Hemodialysis. CPT Pharmacometrics Syst Pharmacol 2016; 5:484-94. [PMID: 27639083 PMCID: PMC5036423 DOI: 10.1002/psp4.12106] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 07/19/2016] [Accepted: 07/20/2016] [Indexed: 02/03/2023]
Abstract
Etelcalcetide is a novel calcimimetic in development for the treatment of secondary hyperparathyroidism (SHPT). A population pharmacokinetic/pharmacodynamic (PK/PD) model was developed relating etelcalcetide exposures to markers of efficacy (parathyroid hormone [PTH]) and safety (calcium) using data from three clinical studies. The semimechanistic model was developed that included allosteric activation pharmacology and understanding of calcium homeostasis. The temporal profiles for all biomarkers were well described by the model. The cooperativity constant was 4.94, confirming allosteric activation mechanism. Subjects with more severe disease (higher PTH baseline) were predicted to experience less pronounced reduction in PTH (percentage change from baseline), but more reduction in calcium (Ca; percentage change from baseline). There was no evidence that dose adjustment by any covariate was needed. Model‐based simulations provided quantitative support to several elements of dosing, such as starting dose, monitoring, and titration timing for registration trials.
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Affiliation(s)
- P Chen
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | | | - J J Perez-Ruixo
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA.,Current address: Janssen Research & Development, Beerse, Belgium
| | - J Xiao
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA.,Clovis Oncology Inc., San Francisco, California, USA
| | | | - A Narayanan
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - J P Gibbs
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - M Melhem
- Department of Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., Thousand Oaks, California, USA.
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9
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Krzyzanski W, Harrold JM, Wu LS, Perez-Ruixo JJ. A cell-level model of pharmacodynamics-mediated drug disposition. J Pharmacokinet Pharmacodyn 2016; 43:513-27. [PMID: 27612462 DOI: 10.1007/s10928-016-9491-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/02/2016] [Indexed: 01/22/2023]
Abstract
We aimed to develop a cell-level pharmacodynamics-mediated drug disposition (PDMDD) model to analyze in vivo systems where the PD response to a drug has an appreciable effect on the pharmacokinetics (PK). An existing cellular level model of PD stimulation was combined with the standard target-mediated drug disposition (TMDD) model and the resulting model structure was parametrically identifiable from typical in vivo PK and PD data. The PD model of the cell population was controlled by the production rate k in and elimination rate k out which could be stimulated or inhibited by the number of bound receptors on a single cell. Simulations were performed to assess the impact of single and repeated dosing on the total drug clearance. The clinical utility of the cell-level PDMDD model was demonstrated by fitting published data on the stimulatory effects of filgrastim on absolute neutrophil counts in healthy subjects. We postulated repeated dosing as a means of detecting and quantifying PDMDD as a single dose might not be sufficient to elicit the cellular response capable of altering the receptor pool to visibly affect drug disposition. In the absence of any PD effect, the model reduces down to the standard TMDD model. The applications of this model can be readily extended to include chemotherapy-induced cytopenias affecting clearance of endogenous hematopoietic growth factors, different monoclonal antibodies and immunogenicity effects on PK.
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Affiliation(s)
| | - John M Harrold
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., One Amgen Center Dr, Thousand Oaks, CA, 91320, USA.
| | - Liviawati S Wu
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., One Amgen Center Dr, Thousand Oaks, CA, 91320, USA
| | - Juan Jose Perez-Ruixo
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., One Amgen Center Dr, Thousand Oaks, CA, 91320, USA.,Janssen Research & Development, Beerse, Antwerp, Belgium
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10
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Krzyzanski W, Xiao JJ, Sasu B, Hinkle B, Perez-Ruixo JJ. Pharmacodynamic Model of Hepcidin Regulation of Iron Homeostasis in Cynomolgus Monkeys. AAPS J 2016; 18:713-27. [PMID: 26917226 PMCID: PMC5256605 DOI: 10.1208/s12248-016-9886-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/09/2016] [Indexed: 01/31/2023] Open
Abstract
Hepcidin (H25) is a hormone peptide synthesized by the liver that binds to ferroportin and blocks iron export. In this study, H25 was inhibited by administration of single and multiple doses of an anti-H25 monoclonal antibody Ab 12B9m in cynomolgus monkeys. The objective of this analysis was to develop a pharmacodynamic model describing the role of H25 in regulating iron homeostasis and the impact of hepcidin inhibition by Ab 12B9m. Total serum H25 and Ab 12B9m were determined in each animal. Corresponding measurements of serum iron and hemoglobin (Hb) were obtained. The PD model consisted of iron pools in serum (FeS), reticuloendothelial macrophages (FeM), hemoglobin (FeHb), and liver (FeL). The iron was assumed to be transported between the FeS, FeHb, and FeM unidirectionally at rates k S, k Hb, and k M. H25 serum concentrations were described by the previously developed PK model with the parameters fixed at their estimates. The serum iron and Hb data were fitted simultaneously. The corresponding estimates of the rate constants were k S/Fe0 = 0.113 h(-1), k M = 0.00191 h(-1), and k Hb = 0.00817 h(-1). The model-based IC50 value for the H25 inhibitory effect on ferroportin activity was 0.398 nM. The PD model predicted a negligible effect of Ab 12B9m on Hb levels for the tested doses. The presented PD model adequately described the serum iron time courses following single and multiple doses of Ab 12B9m. Ab 12B9m-induced inhibition of H25 resulted in a temporal increase in serum and liver iron and a decrease in the iron stored in reticuloendothelial macrophages.
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Affiliation(s)
- Wojciech Krzyzanski
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA.
| | - Jim J Xiao
- Pharmacokinetics and Drug Metabolism, Amgen Inc, Thousand Oaks, California, USA
- Clinical Pharmacology, Clovis Oncology, San Francisco, California, USA
| | - Barbra Sasu
- Oncology, Amgen Inc, Thousand Oaks, California, USA
- Research Oncology, Pfizer, San Francisco, California, USA
| | - Beth Hinkle
- Comparative Biology and Safety Sciences, Amgen Inc, Thousand Oaks, California, USA
| | - Juan Jose Perez-Ruixo
- Pharmacokinetics and Drug Metabolism, Amgen Inc, Thousand Oaks, California, USA
- Janssen Research and Development, Beerse, Belgium
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Krzyzanski W, Sutjandra L, Perez-Ruixo JJ, Sloey B, Chow AT, Wang YM. Pharmacokinetic and pharmacodynamic modeling of romiplostim in animals. Pharm Res 2012; 30:655-69. [PMID: 23250851 DOI: 10.1007/s11095-012-0894-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 09/24/2012] [Indexed: 11/29/2022]
Abstract
PURPOSE Romiplostim is a novel thrombopoiesis-stimulating peptibody that targets the thrombopoietin c-Mpl receptor, resulting in increased platelet production. The pharmacodynamic-mediated disposition (PDMDD) and its stimulatory effect on platelet production in Sprague-Dawley rats, rhesus monkeys, and cynomolgus monkeys following IV bolus and SC administration at various dose levels were determined. METHODS The pharmacokinetic (PK) profile was described by a PDMDD model that accounts for romiplostim binding to the c-Mpl receptor. The PD model contained a series of aging compartments for precursor cells in bone marrow and platelets. The stimulatory function was described by an on-and-off function operating on the fractional receptor occupancy (RO). The threshold effect, RO(thr), and K(D) parameters were determinants of drug potency, whereas S(max) reflected drug efficacy. RESULTS The model implicated that receptor-mediated clearance was negligible. RO(thr) estimated occupancies were 0.288, 0.385, 0.771 for rats, rhesus, and cynomolgus monkeys, respectively. The analogous estimated values of K(D) were 4.05, 2320, and 429 ng/mL, implying that romiplostim was much more potent in rats, which was confirmed by a dose-response (ratio of peak platelet count to baseline) relationship. CONCLUSIONS The model adequately described romiplostim serum concentrations and platelet counts in rats, rhesus monkeys, and cynomolgus monkeys, and quantified linear clearance, PDMDD, and potency of romiplostim.
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Affiliation(s)
- Wojciech Krzyzanski
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, New York, USA
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12
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Abstract
A pharmacodynamic model was developed for platelet counts in 52 patients with immune thrombocytopenia (ITP) receiving subcutaneous romiplostim in 3 phase I/II studies (dose range, 0.2-10 µg/kg). The model consisted of a drug-sensitive progenitor cell compartment linked to a peripheral blood compartment through 4 transition compartments. The baseline platelet count, mean transit time, and kinetics of drug effect constant were 11.1 × 10(9)/L, 170 hours, and 0.6 day(-1), respectively. The ITP patients had a shorter platelet life span and lower progenitor cell production rates than healthy volunteers. Romiplostim response was described for 2 subpopulations. The romiplostim stimulatory effect in ITP patients was 351%/100 µg/wk and 12%/100 µg/wk in 68% and 32% of patients, respectively. Visual and numerical predictive checks suggested accurate prediction of platelet time course and durable response rate in ITP patients. Model-based simulations confirmed the effectiveness of dose reduction to prevent platelet counts >400 × 10(9)/L.
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Xiao JJ, Krzyzanski W, Wang YM, Li H, Rose MJ, Ma M, Wu Y, Hinkle B, Perez-Ruixo JJ. Pharmacokinetics of anti-hepcidin monoclonal antibody Ab 12B9m and hepcidin in cynomolgus monkeys. AAPS J 2010; 12:646-57. [PMID: 20737261 DOI: 10.1208/s12248-010-9222-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 07/09/2010] [Indexed: 12/21/2022]
Abstract
Hepcidin is a key regulator responsible for systemic iron homeostasis. A semi-mechanistic PK model for hepcidin and a fully human anti-hepcidin monoclonal antibody (Ab 12B9m) was developed to describe their total (free + bound) serum concentration-time data after single and multiple weekly intravenous or subcutaneous doses of Ab 12B9m. The model was based on target mediated drug disposition and the IgG-FcRn interaction concepts published previously. Both total Ab 12B9m and total hepcidin exhibited nonlinear kinetics due to saturable Fc-FcRn interaction. Ab 12B9m showed a limited volume of distribution and negligible linear elimination from serum. The nonlinear elimination of Ab 12B9m was attributed to the endosomal degradation of Ab 12B9m that was not bound to the FcRn receptor. The terminal half-life, assumed to be the same for free and total serum Ab 12B9m, was estimated to be 16.5 days. The subcutaneous absorption of Ab 12B9m was described with a first-order absorption rate constant k(a) of 0.0278 h⁻¹, with 86% bioavailability. The model suggested a rapid hepcidin clearance of approximately 800 mL h⁻¹ kg⁻¹. Only the highest-tested Ab 12B9m dose of 300 mg kg⁻¹ week⁻¹ was able to maintain free hepcidin level below the baseline during the dosing intervals. Free Ab 12B9m and free hepcidin concentrations were simulated, and their PK profiles were nonlinear as affected by their binding to each other. Additionally, the total amount of FcRn receptor involved in Ab 12B9m recycling at a given time was calculated empirically, and the temporal changes in the free FcRn levels upon Ab 12B9m administration were inferred.
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Affiliation(s)
- Jim J Xiao
- AMGEN, Thousand Oaks, California 91320, USA.
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Ortega I, Perez-Ruixo JJ, Stuyckens K, Piotrovsky V, Vermeulen A. Modeling the effectiveness of paliperidone ER and olanzapine in schizophrenia: meta-analysis of 3 randomized, controlled clinical trials. J Clin Pharmacol 2010; 50:293-310. [PMID: 20056804 DOI: 10.1177/0091270009346057] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The time course of Positive and Negative Syndrome Scale (PANSS) scores in adult schizophrenia patients was modeled, and the effectiveness of paliperidone extended-release tablets (paliperidone ER) and olanzapine was quantified. Data from 3 randomized, double-blind phase III studies were used. Patients received paliperidone ER (3, 6, 9, 12, or 15 mg), olanzapine 10 mg, or matched placebo once daily for 6 consecutive weeks. An indirect response model implemented using a nonlinear mixed effects approach described the time course of the PANSS. Deterioration rate was modeled as a function of baseline PANSS score, placebo, and drug effects, and the dropout effect. An exponential decrease of the placebo response was also implemented. Paliperidone ER and olanzapine treatment were characterized by a long-lasting drug effect (13%), with a larger but short-lasting placebo effect (40%) and a notable dropout rate. The covariate exploration failed to identify any clinically relevant factors. The nonparametric bootstrap analysis confirmed the acceptable precision of parameter estimates. The visual predictive check supported the model's adequacy to reproduce observed PANSS time courses. The population model describes the time course of PANSS scores in schizophrenia patients and is appropriate for use in clinical trial simulation activities.
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Affiliation(s)
- Ignacio Ortega
- Advanced Modeling and Simulation, Clinical Pharmacology Division, Johnson & Johnson Pharmaceutical Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
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Ramon-Lopez A, Nalda-Molina R, Valenzuela B, Perez-Ruixo JJ. Semi-mechanistic model for neutropenia after high dose of chemotherapy in breast cancer patients. Pharm Res 2009; 26:1952-62. [PMID: 19488837 DOI: 10.1007/s11095-009-9910-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 05/10/2009] [Indexed: 02/06/2023]
Abstract
PURPOSE To describe the absolute neutrophil counts (ANC) profile in breast cancer patients receiving high-dose of chemotherapy and peripheral blood stem-cells (PBSC) transplantation. METHODS Data from 41 subjects receiving cyclophosphamide, thiotepa and carboplatin were used to develop the ANC model consisting of a drug-sensitive progenitor cell compartment, linked to the peripheral blood compartment, through three transition compartments. PBSC were incorporated into the first transit compartment following a zero-order process, k(in), and the rebound effect was explained by a feedback mechanism. A 'kinetics of drug action' model was used to quantify the HDC effect on the progenitor cells according to a linear function, with a slope (alpha). RESULTS The typical of the ANC at baseline (Circ(0)), mean transit time (MTT), feedback parameter (gamma), k(in) and alpha were estimated to be 5,610 x 10(6)/L, 3.25 days, 0.145, 0.954 cell/kg/day and 2.50 h/U, respectively. rHuG-CSF shortens the MTT by 92% and increases the mitotic activity by 120%. Bootstrap analysis, visual predictive check and numerical predictive checks evidenced accurate prediction of the ANC nadir, time to ANC nadir and time to grade 4 neutropenia recovery. CONCLUSION The time course of neutropenia following high-dose of chemotherapy and PBSC transplantation was accurately predicted. Higher amount of CD34+ cells in the PBSC transplantation and earlier administration rHuG-CSF were associated with faster haematological recovery.
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Affiliation(s)
- Amelia Ramon-Lopez
- Pharmacy and Pharmaceutics Division, Department of Engineering, Miguel Hernandez University, San Juan de Alicante, Alicante, Spain
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Samtani MN, Perez-Ruixo JJ, Brown KH, Cerneus D, Molloy CJ. Pharmacokinetic and pharmacodynamic modeling of pegylated thrombopoietin mimetic peptide (PEG-TPOm) after single intravenous dose administration in healthy subjects. J Clin Pharmacol 2009; 49:336-50. [PMID: 19246731 DOI: 10.1177/0091270008329559] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pegylated thrombopoietin mimetic peptide (PEG-TPOm) is a novel, potent thrombopoietin receptor agonist with low immunotoxicity potential that protects against chemotherapy-induced thrombocytopenia in preclinical animal models. The aim of this study was to develop a population pharmacokinetic and pharmacodynamic model of PEG-TPOm following single intravenous doses in healthy subjects. Data were obtained from a double-blind, randomized, placebo-controlled study. A model based on target-mediated drug disposition and precursor pool life spans was applied. Model evaluation was performed through predictive checks and bootstrap analysis. The half-life of PEG-TPOm ranged between 18 and 36 hours, and the estimated distributional volume was 5 L. The increase in platelet counts was observed after a 4-day delay, consistent with the megakaryocyte cell life span. The platelet life span was estimated to be 5 days. After maximum platelets counts were achieved on day 9, platelets returned back to baseline on day 29. Model-based simulations were undertaken to explore pharmacodynamic effects after multiple dosing. Weekly dosing produced a sustained pharmacodynamic response, whereas an interdosing interval >or=2 weeks resulted in fluctuating pharmacodynamic profiles. Thus, the mechanistic pharmacokinetic/pharmacodynamic model was suitable for describing the complex PEG-TPOm pharmacokinetics/pharmacodynamics, including target-mediated disposition, dose-dependent platelet stimulation, and mean life spans of thrombopoietic cell populations.
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Affiliation(s)
- Mahesh N Samtani
- Clinical Pharmacology, Advanced PK-PD Modeling and Simulation, Johnson & Johnson Pharmaceutical R&D, 920 Route 202, PRD 2723, Raritan, NJ 08869, USA.
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Nalda-Molina R, Valenzuela B, Ramon-Lopez A, Miguel-Lillo B, Soto-Matos A, Perez-Ruixo JJ. Population pharmacokinetics meta-analysis of plitidepsin (Aplidin) in cancer subjects. Cancer Chemother Pharmacol 2008; 64:97-108. [PMID: 18941750 DOI: 10.1007/s00280-008-0841-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 09/12/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To characterize the population pharmacokinetics of plitidepsin (Aplidin) in cancer patients. METHODS A total of 283 patients (552 cycles) receiving intravenous plitidepsin as monotherapy at doses ranging from 0.13 to 8.0 mg/m(2) and given as 1- or 24-h infusions every week; 3- or 24-h infusion biweekly; or 1-h infusion daily for 5 consecutive days every 21 days were included in the analysis. An open three-compartment pharmacokinetic model and a nonlinear binding to red blood cells model were used to describe the plitidepsin pharmacokinetics in plasma and blood, respectively, using NONMEM V software. The effect of selected covariates on plitidepsin pharmacokinetics was investigated. Model evaluation was performed using goodness-of-fit plots, posterior predictive check and bootstrap. RESULTS Plasma clearance and its between subject variability (%) was 13.6 l/h (71). Volume of distribution at steady-state was calculated to be 4791 l (59). The parameters B (max) and C (50) of the non-linear blood distribution were 471 microg/l (56) and 41.6 microg/l, respectively. Within the range of covariates studied, age, sex, body size variables, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, creatinine clearance, albumin, total protein, performance status, co-administration of inhibitors or inducers of CYP3A4 and presence of liver metastases were not statistically related to plitidepsin pharmacokinetic parameters. Bootstrap and posterior predictive check evidenced the model was deemed appropriate to describe the time course of plitidepsin blood and plasma concentrations in cancer patients. CONCLUSIONS The integration of phase I/II pharmacokinetic data demonstrated plitidepsin linear elimination from plasma, dose-proportionality up to 8.0 mg/m(2), and time-independent pharmacokinetics. The distribution to red blood cells can be considered linear at doses lower than 5 mg/m(2) administered as 3-h or longer infusion. No clinically relevant covariates were identified as predictors of plitidepsin pharmacokinetics.
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Affiliation(s)
- Ricardo Nalda-Molina
- Department of Engineering, Pharmacy and Pharmaceutics Division, Faculty of Pharmacy, Miguel Hernández University, San Juan de Alicante, Alicante, Spain.
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Krzyzanski W, Perez-Ruixo JJ, Vermeulen A. Basic pharmacodynamic models for agents that alter the lifespan distribution of natural cells. J Pharmacokinet Pharmacodyn 2008; 35:349-77. [PMID: 18551354 PMCID: PMC2673548 DOI: 10.1007/s10928-008-9092-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 04/28/2008] [Indexed: 10/22/2022]
Abstract
A new class of basic indirect pharmacodynamic models for agents that alter the loss of natural cells based on a lifespan concept are presented. The lifespan indirect response (LIDR) models assume that cells (R) are produced at a constant rate (k(in)), survive during a certain duration T(R), and finally are lost. The rate of cell loss is equal to the production rate but is delayed by T(R). A therapeutic agent can increase or decrease the baseline cell lifespan to a new cell lifespan, T(D), by temporally changing the proportion of cells belonging to the two modes of the lifespan distribution. Therefore, the change of lifespan at time t is described according to the Hill function, H(C(t)), with capacity (E(max)) and sensitivity (EC(50)), and the pharmacokinetic function C(t). A one-compartment cell model was examined through simulations to describe the role of pharmacokinetics, pharmacodynamics and cell properties for the cases where the drug increases (T(D) > T(R)) or decreases (T(D) < T(R)) the cell lifespan. The area under the effect curve (AUCE) and explicit solutions of LIDR models for large doses were derived. The applicability of the model was further illustrated using the effects of recombinant human erythropoietin (rHuEPO) on reticulocytes. The cases of both stimulation of the proliferation of bone marrow progenitor cells and the increase of reticulocyte lifespans were used to describe mean data from healthy subjects who received single subcutaneous doses of rHuEPO ranging from 20 to 160 kIU. rHuEPO is about 4.5-fold less potent in increasing reticulocyte survival than in stimulating the precursor production. A maximum increase of 4.1 days in the mean reticulocyte lifespan was estimated and the effect duration on the lifespan distribution was dose dependent. LIDR models share similar properties with basic indirect response models describing drug stimulation or inhibition of the response loss rate with the exception of the presence of a lag time and a dose independent peak time. The current concept can be applied to describe the pharmacodynamic effects of agents affecting survival of hematopoietic cell populations yielding realistic physiological parameters.
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Affiliation(s)
- Wojciech Krzyzanski
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 14260, USA.
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Hing J, Perez-Ruixo JJ, Stuyckens K, Soto-Matos A, Lopez-Lazaro L, Zannikos P. Mechanism-based Pharmacokinetic/Pharmacodynamic Meta-analysis of Trabectedin (ET-743, Yondelis) Induced Neutropenia. Clin Pharmacol Ther 2007; 83:130-43. [PMID: 17597713 DOI: 10.1038/sj.clpt.6100259] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Myelosuppression was found to be one of the main toxicities of trabectedin (ET-743, Yondelis) during phase I/II studies. Our objective was to develop a pharmacokinetic-pharmacodynamic (PK/PD) model that describes the time course of the absolute neutrophil counts (ANCs) in cancer patients receiving trabectedin. Data from 699 patients who received intravenous trabectedin as monotherapy (dose range: 0.006-1.8 mg/m2) as a 1-, 3-, or 24-h infusion every 21 days; 1- or 3-h infusion on days 1, 8, and 15 every 28 days; or a 1-h infusion daily for 5 consecutive days every 21 days were used to develop (N=405; ANCs=7,291) and validate (N=294; ANCs=5,029) the model. The PK/PD model comprised a trabectedin-sensitive progenitor cell compartment, linked to the peripheral blood compartment, through three transition compartments representing the maturation chain in the bone marrow. To capture the rebound effect due to endogenous growth factors, the model included a feedback mechanism. The model estimated three system-related parameters: ANC at baseline (Circ0), mean transit time in bone marrow (MTT), and a feedback parameter (gamma). A first-order process quantified by the rate constant k(e0) described the trabectedin concentrations at the effect compartment (C(e)), which were assumed to reduce the proliferation rate and/or to increase the killing rate of the progenitor cells according to the function alphaC(e)beta. The model was qualified and simulations were undertaken to evaluate the neutropenia schedule dependency and the effects of selected covariates. NONMEM software was used to perform the modeling and simulation analyses. For a typical man of 70 kg, the mean values (between-subject variability; %) of the Circ0, MTT, gamma, k(e0), alpha, and beta were estimated to be 4.46 x 10(9)/l (37.9%), 4.0 days (37.5%), 0.218 (41.8%), 2.09 h(-1) (77.9%), 2.00 l/microg (85.1%), and 1.26, respectively. Although in women, k(e0) was reduced by 29% and a 25% increase in body weight resulted in a 12.6% reduction in the beta parameter, the clinical relevance of these effects is limited. The model evaluation procedure indicated accurate prediction of the observed incidence of neutropenia grades 3 and 4 across the dosing regimens evaluated. Simulations indicated that trabectedin dose and interdose interval, but not infusion duration, are the main determinants of the neutropenia severity. The model-predicted time course of the ANC and its variability confirmed that neutropenia is reversible, of short duration, and non-cumulative. The extent and time course of neutropenia following six different dosing regimens of trabectedin were well predicted by the semiphysiological PK/PD model.
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Affiliation(s)
- J Hing
- Clinical Pharmacology Division, Titusville, New Jersey, USA
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Abstract
OBJECTIVE The aim of this analysis was to develop a population pharmacokinetic model to describe the pharmacokinetics of recombinant human erythropoietin (rHuEPO) in healthy subjects, after intravenous and subcutaneous administration over a wide dose range, and to examine the influence of demographic characteristics and other covariates on the pharmacokinetic parameters of rHuEPO. METHODS Erythropoietin serum concentration data were available from 16 studies comprising 49 healthy subjects who received rHuEPO intravenous doses from 10 to 300 IU/kg, 427 healthy subjects who received rHuEPO subcutaneous doses from 1 to 2400 IU/kg, and 57 healthy subjects who received placebo and where endogenous erythropoietin concentrations were measured. Different pharmacokinetic models were fitted to the dataset using nonlinear mixed-effects modeling software (NONMEM, Version V, Level 1). Several patient covariates were tested in order to quantify the effect on rHuEPO pharmacokinetic parameters. Model evaluation was examined using a posterior predictive check. RESULTS Erythropoietin showed a diurnal baseline variation of +/-20%, described with a dual cosine model. Disposition was described with a two-compartment model with a small volume of distribution (6L) and parallel linear and nonlinear clearance. Total clearance varied between 0.3 and 0.9 L/h over the concentration range studied. A dual absorption model was used to characterise the rHuEPO absorption from the subcutaneous formulation and consisted of a faster pathway described as a sequential zero- and first-order absorption process and a parallel slower pathway characterised as a zero-order process. The bioavailability of subcutaneous rHuEPO increased from 30% at low doses to 71% at the highest dose of 160 kIU and was described using a hyperbolic model. The most important covariate effects were a decrease in the first-order absorption rate constant (k(a)) with increasing age, an increase in subcutaneous bioavailability with increasing baseline haemoglobin, and a decrease in bioavailability with increasing bodyweight. A posterior predictive check showed no systematic deviation of the simulated data from the observed values. CONCLUSION The population pharmacokinetic model developed is suitable to describe the pharmacokinetic behaviour of rHuEPO after intravenous and subcutaneous administration in healthy subjects, over a wide dose range.
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Perez-Ruixo JJ, Piotrovskij V, Zhang S, Hayes S, De Porre P, Zannikos P. Population pharmacokinetics of tipifarnib in healthy subjects and adult cancer patients. Br J Clin Pharmacol 2007; 62:81-96. [PMID: 16842381 PMCID: PMC1885079 DOI: 10.1111/j.1365-2125.2006.02615.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
AIMS To characterize the population pharmacokinetics of tipifarnib. METHODS A total of 1083 subjects treated orally with a solution, capsule or tablet formulations of tipifarnib, given as a single dose or as multiple twice-daily doses (range 25-1300 mg) were combined with data from 1, 2 and 24 h intravenous infusions. A total of 3445 concentrations in the index data set were fitted by an open three-compartment linear disposition model with sequential zero-order input into the depot compartment, followed by a first-order absorption process, and lag time, using NONMEM V. The effect of patient covariates on tipifarnib pharmacokinetics was explored. The model was evaluated using goodness of fit plots and relative error measurements for 3894 concentrations in the test data set. Computer simulations were undertaken to evaluate the effect of covariates on tipifarnib pharmacokinetics. RESULTS Tipifarnib oral bioavailability (26.7%) did not differ between the formulations. The absorption rate from the solution was faster than from the solid forms. Whereas the absorption rate and systemic clearance were more rapid in healthy subjects, the extent of absorption and the steady-state volume of distribution were comparable in cancer patients and healthy subjects. Systemic clearance in cancer patients (21.9 l h-1) exhibited a statistically significant relationship with total bilirubin. The typical volume of the central compartment in cancer patients (54.6 l 70 kg-1) was directly proportional to body weight. The clinical relevance of these covariates in cancer patients is questionable as there was a substantial overlap in simulated concentration-time profiles across a wide range of covariate values. CONCLUSIONS A population PK approach has been used to integrate data gathered during clinical development and to characterize the pharmacokinetics of tipifarnib. Individualization of dose based on body weight or total bilirubin concentration in adult cancer patients is not warranted.
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Affiliation(s)
- Juan Jose Perez-Ruixo
- Global Clinical Pharmacokinetics and Clinical Pharmacology Division, Beerse, Belgium.
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Ortega I, Rodriguez M, Suarez E, Perez-Ruixo JJ, Calvo R. Modeling methadone pharmacokinetics in rats in presence of P-glycoprotein inhibitor valspodar. Pharm Res 2007; 24:1299-308. [PMID: 17380267 DOI: 10.1007/s11095-007-9251-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 01/25/2007] [Indexed: 11/26/2022]
Abstract
PURPOSE To quantify the in vivo role of P-glycoprotein (P-gp) in the pharmacokinetics of methadone after intravenous and oral administration, using valspodar as a P-gp inhibitor. MATERIALS AND METHODS Methadone plasma concentrations after intravenous (0.35 mg/kg) and oral (6 mg/kg) administration were analyzed, in absence and presence of valspodar, using nonlinear mixed effects modeling (NONMEM V). Non-parametric bootstrap analysis and posterior predictive check were employed as model evaluation techniques. RESULTS The pharmacokinetics of methadone in the rat was successfully modeled using a two-compartmental model with a linear elimination from the central compartment and a first-order absorption process with lag time. Valspodar increased methadone F by 122% (95%CI: 34-269%) and decreased the V ( c ) and V ( p ) by 35% (95%CI: 16-49%) and 81% (95%CI: 63-93%), respectively. No effect of valspodar on other pharmacokinetic parameters was discernible. The non-parametric bootstrap analysis confirmed the absence of bias on the parameter estimates, and visual predictive check evidence the adequacy of the model to reproduce the observed time course of methadone plasma concentrations. CONCLUSION Valspodar increased methadone's bioavailability as consequence of P-gp inhibition, which resulted in an increased analgesic effect of methadone.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Administration, Oral
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/blood
- Analgesics, Opioid/pharmacokinetics
- Animals
- Biological Availability
- Cyclosporins/administration & dosage
- Cyclosporins/pharmacology
- Drug Interactions
- Humans
- Infusions, Intravenous
- Methadone/administration & dosage
- Methadone/blood
- Methadone/pharmacokinetics
- Models, Biological
- Nonlinear Dynamics
- Rats
- Rats, Sprague-Dawley
- Reproducibility of Results
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Affiliation(s)
- Ignacio Ortega
- Department of Pharmacology, University of the Basque Country, Leioa, Vizcaya, Spain
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Abstract
AIMS To explore the potential relationship between systemic exposure to tipifarnib and the incidence of toxicity in cancer patients. METHODS Data from 673 subjects (540 receiving tipifarnib and 133 receiving placebo) were included in the analysis. Tipifarnib was administered in doses ranging from 100 mg to 850 mg twice daily under fed conditions for 21 days in a 28 day cycle. Univariate and multivariate logistic regression models were used to evaluate the relationships between tipifarnib exposure and haematological (neutropenia and thrombocytopenia) and nonhaematological toxicities. Tipifarnib exposure was quantified as the area under the curve during the first cycle of chemotherapy (AUC), the maximum plasma concentration (C(max)), the time above plasma tipifarnib concentrations of 400 (T400) and 600 ng ml(-1) (T600), the cumulative area under the curve (AUC(T)), and the area under the curve density (AUC(D)), defined as the ratio AUC(T) to the duration of treatment. The nonhaematological toxicities measured were elevation of AST, ALT, bilirubin and serum creatinine, the occurrence of a skin rash, CNS or peripheral neuropathy, nausea and vomiting, diarrhoea and inflammation of the gastrointestinal tract. Odds ratios (OR) associated with drug exposure were used to measure the effect of the drug. RESULTS Tipifarnib AUC exhibited a positive and significant association with neutropenia grade > or =3 (OR 1.69, 95% CI 1.47, 1.95) and thrombocytopenia grade > or =3 (OR 1.41, 95% CI 1.21, 1.63) in patients with solid tumours, but not in refractory or relapsed AML patients. The incidence of exposure-related nonhaematological toxicity is small regardless of tumour type. No association was found between tipifarnib AUC and the elevation of AST, ALT and total bilirubin, and nausea and vomiting. There was a weak relationship between tipifarnib AUC and serum creatinine elevation (OR 1.18, 95% CI 1.11, 1.26), CNS (OR 1.05, 95% CI 1.01, 1.10) and peripheral neurotoxicity (OR 1.10, 95% CI 1.03, 1.18), diarrhoea (OR 1.14, 95% CI 1.08, 1.21), gastrointestinal tract inflammation (OR 1.13, 95% CI 1.07, 1.19), and skin rash (OR 1.10, 95% CI 1.04, 1.17). CONCLUSIONS In those patients who develop severe toxicity, dose reduction may improve the tolerability of tipifarnib. However, an exposure-guided approach to dosage adjustment to limit haematological and nonhaematological toxicity is not warranted.
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Affiliation(s)
- Juan Jose Perez-Ruixo
- Clinical Pharmacology Division, Johnson & Johnson Pharmaceutical Research & Development, Beerse, Belgium.
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Krzyzanski W, Perez-Ruixo JJ. An assessment of recombinant human erythropoietin effect on reticulocyte production rate and lifespan distribution in healthy subjects. Pharm Res 2007; 24:758-72. [PMID: 17318417 DOI: 10.1007/s11095-006-9195-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 11/21/2006] [Indexed: 12/13/2022]
Abstract
PURPOSE An empirical pharmacodynamic model was developed to assess the effect of recombinant human erythropoietin (rHu-EPO) treatment on the reticulocyte production rate and lifespan distribution. MATERIALS AND METHODS Single doses of rHu-EPO at levels 20, 40, 60, 90, 120, and 160 kIU were administered to healthy volunteers (n = 8 per dose level). Erythropoietin plasma concentrations as well as hematologic responses were measured up to 42 days. The hematological data were used to determine explicit relationships between reticulocyte and red blood cell counts (RBC) and the reticulocytes' production rate and lifespan distribution. RESULTS The parameter estimates obtained by simultaneous fitting of the model to the reticulocyte and RBC data revealed that rHu-EPO transiently increased the reticulocyte lifespan from the baseline value of 1.7 days to 3.4 days and the effect lasted for 8.3 days. The dose dependent increase in the reticulocyte production had the maximal value of 77.5 10(9) cells/l/day and was followed by a rebound that was less than 9% of the baseline value. Both reticulocyte and RBC responses were preceded by a dose-independent lag time of 1.7 days. CONCLUSIONS The effect of rHu-EPO on the reticulocyte production rate and lifespan distribution was characterized. The results of the present study can be further utilized in building more mechanistic pharmacodynamic models of rHu-EPO stimulatory effects.
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Affiliation(s)
- Wojciech Krzyzanski
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 14260, USA
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Perez-Ruixo JJ, Zannikos P, Hirankarn S, Stuyckens K, Ludwig EA, Soto-Matos A, Lopez-Lazaro L, Owen JS. Population Pharmacokinetic Meta-Analysis of Trabectedin (ET-743,??Yondelis??) in Cancer Patients. Clin Pharmacokinet 2007; 46:867-84. [PMID: 17854236 DOI: 10.2165/00003088-200746100-00005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVE To characterise the population pharmacokinetics of trabectedin (ET-743, Yondelis(R)) in cancer patients. METHODS A total of 603 patients (945 cycles) receiving intravenous trabectedin as monotherapy at doses ranging from 0.024 to 1.8 mg/m(2) and given as a 1-, 3- or 24-hour infusion every 21 days; a 1- or 3-hour infusion on days 1, 8 and 15 of a 28-day cycle; or a 1-hour infusion daily for 5 consecutive days every 21 days were included in the analysis. An open four-compartment pharmacokinetic model with linear elimination, linear and nonlinear distribution to the deep and shallow peripheral compartments, respectively, and a catenary compartment off the shallow compartment was developed to best describe the index dataset using NONMEM V software. The effect of selected patient covariates on trabectedin pharmacokinetics was investigated. Model evaluation was performed using goodness-of-fit plots and relative error measurements for the test dataset. Simulations were undertaken to evaluate covariate effects on trabectedin pharmacokinetics. RESULTS The mean (SD) trabectedin elimination half-life was approximately 180 (61.4) hours. Plasma accumulation was limited when trabectedin was given every 3 weeks. Systemic clearance (31.5 L/h, coefficient of variation 51%) was 19.2% higher in patients receiving concomitant dexamethasone. The typical values of the volume of distribution at steady state for male and female patients were 6070L and 5240L, respectively. Within the range studied, age, body size variables, AST, ALT, alkaline phosphatase, lactate dehydrogenase, total bilirubin, creatinine clearance, albumin, total protein, Eastern Cooperative Oncology Group performance status and presence of liver metastases were not statistically related to trabectedin pharmacokinetic parameters. The pharmacokinetic parameters of trabectedin were consistent across the infusion durations and dose regimens evaluated. CONCLUSIONS The integration of trabectedin pharmacokinetic data demonstrated linear elimination, dose-proportionality up to 1.8 mg/m(2) and time-independent pharmacokinetics. The pharmacokinetic impact of dexamethasone and sex covariates is probably limited given the moderate to large interindividual pharmacokinetic variability of trabectedin. The antiemetic and hepatoprotective effects are still a valid rationale to recommend dexamethasone as a supportive treatment for trabectedin.
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Affiliation(s)
- Juan Jose Perez-Ruixo
- Clinical Pharmacology, Johnson & Johnson Pharmaceutical Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium.
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Perez-Ruixo JJ, Zannikos P, Ozdemir V, Franc MA, Francke S, Piotrovsky V. Effect of CYP2D6 genetic polymorphism on the population pharmacokinetics of tipifarnib. Cancer Chemother Pharmacol 2006; 58:681-91. [PMID: 16544144 DOI: 10.1007/s00280-006-0215-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 02/16/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Evaluate the effect of CYP2D6 genotype on the pharmacokinetics of tipifarnib. METHODS A total of 268 subjects included in six clinical trials were treated orally with tablet formulation of tipifarnib, as a single dose or as multiple b.i.d. doses (range 50-600 mg), and/or intravenously following 1, 2, and 24 h infusions. A total of 2,575 tipifarnib concentrations were fitted to an open three-compartment linear disposition model with sequential zero-order input into the depot compartment, followed by a first-order absorption process, and lag time, using NONMEM V. The effect of CYP2D6 genotype was explored as a covariate for tipifarnib systemic clearance and absolute bioavailability. Likelihood ratio test was used to compare these parameters in homozygous extensive metabolizers (EM) (N=152), heterozygous EM (N=97), or poor metabolizers (PM) (N=19). Computer simulations were undertaken to explore the CYP2D6 genotype effect on the tipifarnib pharmacokinetics. RESULTS The ratio of tipifarnib systemic clearance for the heterozygous EM and the PM subjects, relative to the homozygous EM group, were 0.95 (95%CI 0.87-1.03) and 0.96 (95%CI 0.82-1.11), respectively (chi2=2.376, df=2, P=0.305). The ratio of tipifarnib absolute bioavailability for the heterozygous EM and the PM, relative to the homozygous EM, were 1.06 (95%CI 0.83-1.30) and 0.95 (95%CI 0.55-1.34), respectively (chi2=1.398, df=2, P=0.497). CONCLUSIONS These results indicate that CYP2D6 genetic polymorphism does not appreciably influence the pharmacokinetics of tipifarnib. Hence, concomitant administration of potent CYP2D6 inhibitors is anticipated to have little or no significant impact on the systemic exposure to tipifarnib.
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Affiliation(s)
- Juan Jose Perez-Ruixo
- Clinical Pharmacology and Experimental Medicine Division, Johnson & Johnson Pharmaceutical Research & Development, a Division of Janssen Pharmaceutica NV. Turnhoutseweg 30, 2340, Beerse, Belgium.
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Rosenberg JE, von der Maase H, Seigne JD, Mardiak J, Vaughn DJ, Moore M, Sahasrabudhe D, Palmer PA, Perez-Ruixo JJ, Small EJ. A phase II trial of R115777, an oral farnesyl transferase inhibitor, in patients with advanced urothelial tract transitional cell carcinoma. Cancer 2005; 103:2035-41. [PMID: 15812833 DOI: 10.1002/cncr.21023] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND R115777 is a potent farnesyl transferase inhibitor and has significant antitumor effects in vitro and in vivo. METHODS The objective of the current study was to determine the objective response proportion in patients with metastatic transitional cell carcinoma (TCC) of the urothelial tract who received treatment with R115777 at a dose of 300 mg orally given twice daily for 21 days followed by 7 days of rest for every 4-week cycle. Thirty-four patients with TCC were enrolled in this Phase II study. Patients were allowed to have received a maximum of one prior systemic chemotherapy regimen, not including chemoradiation or neoadjuvant chemotherapy. All patients were required to have an Eastern Cooperative Oncology Group performance status of 0-2 and adequate bone marrow, hepatic, and kidney function. RESULTS Twice daily administration of oral R115777 was tolerated well. R115777 was absorbed rapidly after oral administration. Grade 3-4 neutropenia (according to the National Cancer Institute Common Toxicity Criteria [version 2.0]) was observed in 5 patients (15%). Grade 3-4 nonhematologic toxicity was rare, consisting of rash and diarrhea in 1 patient each. Two patients (6%) without prior chemotherapy demonstrated partial responses. Thirteen patients (38%) achieved disease stabilization according to World Health Organization criteria that lasted a median of 4 months. No complete responses were observed. CONCLUSIONS The objective response rate of R115777 was not sufficient to warrant future investigation in TCC as a single agent. Preliminary evidence of the activity of R115777 in 2 chemotherapy-naive patients may warrant further investigation in combination with first-line chemotherapy.
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Affiliation(s)
- Jonathan E Rosenberg
- Department of Medicine, University of California, San Francisco, California 94115, USA.
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Rao S, Cunningham D, de Gramont A, Scheithauer W, Smakal M, Humblet Y, Kourteva G, Iveson T, Andre T, Dostalova J, Illes A, Belly R, Perez-Ruixo JJ, Park YC, Palmer PA. Phase III double-blind placebo-controlled study of farnesyl transferase inhibitor R115777 in patients with refractory advanced colorectal cancer. J Clin Oncol 2004; 22:3950-7. [PMID: 15459217 DOI: 10.1200/jco.2004.10.037] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To determine whether R115777 improves survival in patients with refractory advanced colorectal cancer (CRC) in a multicenter, double-blind, prospective randomized study. PATIENTS AND METHODS Three hundred sixty-eight patients were randomly assigned to R115777 (300 mg twice daily) orally for 21 days every 28 days or placebo in a 2:1 ratio. All patients received best supportive care. The primary end point was overall survival; secondary end points were progression free survival, tumor response, toxicity, and quality of life. RESULTS The two treatment groups were well balanced for baseline demographics, including previous chemotherapy for advanced CRC. The median overall survival for R115777 was 174 days (95% CI, 157 to 198 days), and 185 days (95% CI, 158 to 238 days) for those patients receiving placebo (P =.376). One patient achieved a partial response in the R115777 arm. Stable disease (> 3 months) was observed in 24.3% patients in the R115777 group compared to 12.8% in the placebo arm. This did not translate into a statistically significant increase in progression-free survival. Overall, treatment was well tolerated. There was an increased incidence of reversible myelosuppression (neutropenia, thrombocytopenia), rash, and grade 1 to 2 diarrhea in the R115777 arm. There was no statistically significant difference in quality of life between arms. CONCLUSION Single agent R115777, given at this dose and schedule, has an acceptable toxicity profile, but does not improve overall survival compared to best supportive care alone in refractory advanced CRC.
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Affiliation(s)
- S Rao
- Royal Marsden Hospital, Downs Rd, Sutton, Surrey SM2 5PT, United Kingdom
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Johnston SRD, Hickish T, Ellis P, Houston S, Kelland L, Dowsett M, Salter J, Michiels B, Perez-Ruixo JJ, Palmer P, Howes A. Phase II study of the efficacy and tolerability of two dosing regimens of the farnesyl transferase inhibitor, R115777, in advanced breast cancer. J Clin Oncol 2003; 21:2492-9. [PMID: 12829668 DOI: 10.1200/jco.2003.10.064] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE R115777 is an orally active farnesyl transferase inhibitor that specifically blocks farnesylation of proteins involved in growth-factor-dependent cell-signal-transduction pathways. We conducted a phase II study in 76 patients with advanced breast cancer. PATIENTS AND METHODS Two cohorts of patients were recruited sequentially. The first cohort (n = 41) received a continuous dosing [CD] regimen of R115777 400 or 300 mg bid. The second cohort (n = 35) received 300 mg bid in a cyclical regimen of 21 days of treatment followed by 7 days of rest (intermittent dosing [ID]). RESULTS In the CD cohort, four patients (10%) had a partial response (PR) and six patients (15%) had stable disease at > or = 24 weeks (SD). In the ID cohort, five patients (14%) had a PR and three patients (9%) had prolonged SD. The first six patients in the CD cohort treated at 400 mg bid all developed grade 3 to 4 neutropenia, so the subsequent 35 patients were treated at 300 mg bid. The incidence of hematologic toxicity was significantly lower in the ID than in the CD (300-mg bid) cohort: grade 3 to 4 neutropenia (14% v 43%; P =.016) and grade 3 to 4 thrombocytopenia (3% v 26%; P =.013). One patient in the ID cohort developed grade 2 to 3 neurotoxicity compared with 15 patients in the CD cohort (3% v 37%; P =.0004). CONCLUSION The farnesyl transferase inhibitor R115777 has demonstrated clinical activity in patients with metastatic breast cancer, and the ID regimen has a significantly improved therapeutic index compared with the CD regimen.
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