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Prevedel NE, Mee MW, Wood GA, Coomber BL. Effect of proteasome inhibitors on canine lymphoma cell response to CHOP chemotherapy in vitro. Vet Comp Oncol 2024; 22:96-105. [PMID: 38237918 DOI: 10.1111/vco.12957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/14/2023] [Accepted: 12/12/2023] [Indexed: 02/13/2024]
Abstract
The standard treatment for canine lymphoma is the CHOP chemotherapy regimen. Proteasome inhibitors have been employed with CHOP for the treatment of human haematological malignancies but remain to be fully explored in canine lymphoma. We identified an association between poor response to CHOP chemotherapy and high mRNA expression levels of proteasomal subunits in a cohort of 15 canine lymphoma patients, and sought to determine the effect of proteasome inhibitors on the viability of a canine B-cell lymphoma cell line (CLBL-1). The aim of this study was to investigate whether proteasome inhibitors sensitize these cells to the CHOP agents doxorubicin, vincristine and cyclophosphamide (as 4-hydroxycyclophosphamide/4-HC). CLBL-1 cells were sensitive to proteasome inhibition by bortezomib and ixazomib. The IC50 of bortezomib was 15.1 nM and of ixazomib was 59.14 nM. Proteasome inhibitors plus doxorubicin had a synergistic effect on CLBL-1 viability; proteosome inhibitors plus vincristine showed different effects depending on the combination ratio, and there was an antagonistic effect with 4-HC. These results may have clinical utility, as proteasome inhibition could potentially be used with a synergizing CHOP compound to improve responsiveness to chemotherapy for canine lymphoma patients.
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Affiliation(s)
- Nicholas E Prevedel
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Miles W Mee
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Geoffrey A Wood
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Brenda L Coomber
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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2
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Iwaki Y, Lindley SES, Bergman N, Smith BF, Pondugula SR. An evaluation of the combination effect of zoledronate and chemotherapeutic agents in canine osteosarcoma cells. Front Vet Sci 2024; 11:1327377. [PMID: 38420207 PMCID: PMC10900512 DOI: 10.3389/fvets.2024.1327377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/17/2024] [Indexed: 03/02/2024] Open
Abstract
Introduction Osteosarcoma (OSA) is an aggressive form of bone cancer in both dogs and humans. The treatment options for metastatic (stage III) OSA are currently limited and the prognosis is poor. Zoledronate, a second generation amino-bisphosphonate, is commonly used for palliation of cancer induced bone pain. Zoledronate has also demonstrated anti-cancer properties and possibly enhances the cytotoxicity of doxorubicin in a canine histiocytosis cell line and human prostatic cancer cell line. The goal of this study was to evaluate the combination effect of zoledronate and various chemotherapeutic drugs in canine OSA cells. Methods Canine OSA cell line (D17), cells from two canine primary OSAs, and MDCK, a canine kidney cell line, were used to evaluate the therapeutic potential of these drugs. Carboplatin, doxorubicin, vinorelbine, toceranib, and isophosphoramide mustard (active metabolite of ifosfamide) were used as chemotherapeutic agents. First, cells were treated with either zoledronate or chemotherapy drug alone for 72 hours. Cell viability was assessed using CellTiter Glo and IC5, IC10, IC20, and IC50 were calculated. Second, cells were treated with a combination of zoledronate and each chemotherapeutic agent at their IC5, IC10, IC20, and IC50 concentrations. After 72 hours, cell viability was assessed by CellTiter Glo. Results and discussion Zoledronate, carboplatin, doxorubicin, vinorelbine, and isophosphoramide mustard showed concentration dependent decrease in cell viability. Toceranib showed decreased cell viability only at higher concentrations. When zoledronate was used in combination with chemotherapy drugs, while it showed potential synergistic effects with toceranib, potential antagonistic effects with vinorelbine and isophosphoramide mustard were observed. However, the results differed by cell line and thus, further evaluation is warranted to understand the exact mechanism of action.
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Affiliation(s)
- Yoshimi Iwaki
- Department of Clinical Science, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Stephanie E S Lindley
- Department of Clinical Science, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Noelle Bergman
- Department of Clinical Science, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Bruce F Smith
- Scott Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Satyanarayana R Pondugula
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn, AL, United States
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3
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Lee JB, Zhou S, Chiang M, Zang X, Kim TH, Kagan L. Interspecies prediction of pharmacokinetics and tissue distribution of doxorubicin by physiologically-based pharmacokinetic modeling. Biopharm Drug Dispos 2020; 41:192-205. [PMID: 32342986 DOI: 10.1002/bdd.2229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 04/18/2020] [Accepted: 04/22/2020] [Indexed: 12/12/2022]
Abstract
The aim of the study was to develop a physiologically-based pharmacokinetic (PBPK) model to describe and predict whole-body disposition of doxorubicin following intravenous administration. The PBPK model was established using previously published data in mice and included 10 tissue compartments: lungs, heart, brain, muscle, kidneys, pancreas, intestine, liver, spleen, adipose tissue, and plasma. Individual tissues were described by either perfusion-limited or permeability-limited models. All parameters were simultaneously estimated and the final model was able to describe murine data with good precision. The model was used for predicting doxorubicin disposition in rats, rabbits, dogs, and humans using interspecies scaling approaches and was qualified using plasma and tissue observed data. Reasonable prediction of the plasma pharmacokinetics and tissue distribution was achieved across all species. In conclusion, the PBPK model developed based on a rich dataset obtained from mice, was able to reasonably predict the disposition of doxorubicin in other preclinical species and humans. Applicability of the model for special populations, such as patients with hepatic impairment, was also demonstrated. The proposed model will be a valuable tool for optimization of exposure profiles of doxorubicin in human patients.
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Affiliation(s)
- Jong Bong Lee
- Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA
| | - Simon Zhou
- Translational Development and Clinical Pharmacology, Celgene Corporation, NJ, 07920, USA
| | - Manting Chiang
- Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA.,Center of Excellence for Pharmaceutical Translational Research and Education, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA
| | - Xiaowei Zang
- Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA
| | - Tae Hwan Kim
- College of Pharmacy, Daegu Catholic University, Gyeongsan, Republic of Korea, 38430
| | - Leonid Kagan
- Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA.,Center of Excellence for Pharmaceutical Translational Research and Education, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, NJ, 08854, USA
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4
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Thamm DH, Gustafson DL. Drug dose and drug choice: Optimizing medical therapy for veterinary cancer. Vet Comp Oncol 2019; 18:143-151. [PMID: 31487110 DOI: 10.1111/vco.12537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/29/2019] [Accepted: 09/02/2019] [Indexed: 12/18/2022]
Abstract
Although novel agents hold great promise for the treatment of animal neoplasia, there may be room for significant improvement in the use of currently available agents. These improvements include altered dosing schemes, novel combinations, and patient-specific dosing or selection of agents. Previous studies have identified surrogates for "individualized dose intensity,", for example, patient size, development of adverse effects, and pharmacokinetic parameters, as potential indicators of treatment efficacy in canine lymphoma, and strategies for patient-specific dose escalation are discussed. Strategies for treatment selection in individual patients include conventional histopathology, protein-based target assessment (eg, flow cytometry, immunohistochemistry, and mass spectrometry), and gene-based target assessment (gene expression profiling and targeted or global sequencing strategies). Currently available data in animal cancer evaluating these strategies are reviewed, as well as ongoing studies and suggestions for future directions.
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Affiliation(s)
- Douglas H Thamm
- Flint Animal Cancer Center, Colorado State University, Fort Collins, Colorado.,Cell and Molecular Biology Graduate Program, Colorado State University, Fort Collins, Colorado.,Developmental Therapeutics Program, University of Colorado Comprehensive Cancer Center, Fort Collins, Colorado
| | - Daniel L Gustafson
- Flint Animal Cancer Center, Colorado State University, Fort Collins, Colorado.,Cell and Molecular Biology Graduate Program, Colorado State University, Fort Collins, Colorado.,Developmental Therapeutics Program, University of Colorado Comprehensive Cancer Center, Fort Collins, Colorado
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5
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Iturriaga MP, Paredes R, Arias JI, Torres CG. Meloxicam decreases the migration and invasion of CF41.Mg canine mammary carcinoma cells. Oncol Lett 2017; 14:2198-2206. [PMID: 28781660 PMCID: PMC5530185 DOI: 10.3892/ol.2017.6400] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 03/03/2017] [Indexed: 11/18/2022] Open
Abstract
Cyclooxygenase (COX)-2 expression is positively correlated with malignant features in canine mammary carcinomas. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX activity and may therefore possess anticancer effects. Meloxicam is an NSAID that is widely used in human and veterinary medicine. High concentrations of meloxicam have been reported to be antitumorigenic in vitro; however, the effect of meloxicam at concentrations that are equivalent to those that can be obtained in vivo remains unknown. In the current study, the in vitro effects of low-dose meloxicam (0.25 µg/ml) on CF41.Mg canine mammary carcinoma cells were evaluated. The effects on cell proliferation, apoptosis, cell migration and invasion, in addition to the expression of different molecules associated with tumor invasiveness were analyzed. No effect on cell viability and apoptosis were observed. However, cell migration and invasion were significantly reduced following treatment with meloxicam. MMP-2 expression and activity were similarly reduced, explaining the impaired cell invasion. In addition, β-catenin expression was downregulated, while its phosphorylation increased. These results indicate that 0.25 µg/ml meloxicam reduces cell migration and invasion, in part through modulating MMP-2 and β-catenin expression. Additional studies are required to elucidate the mechanism associated with the anti-invasive effect of meloxicam on CF41.Mg cells. The results of the present study suggest that meloxicam has a potential adjunctive therapeutic application, which could be useful in controlling the invasion and metastasis of canine mammary carcinomas.
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Affiliation(s)
- María P Iturriaga
- Laboratory of Ecosystem Health, Faculty of Ecology and Natural Resources, Universidad Andres Bello, Santiago 8370251, Chile
| | - Rodolfo Paredes
- School of Veterinary Medicine, Faculty of Ecology and Natural Resources, Universidad Andres Bello, Santiago 8370251, Chile
| | - Jose I Arias
- Laboratory of Biomedicine and Regenerative Medicine, Department of Clinical Sciences, Faculty of Veterinary and Animal Sciences, University of Chile, Santiago 8820808, Chile
| | - Cristian G Torres
- Laboratory of Biomedicine and Regenerative Medicine, Department of Clinical Sciences, Faculty of Veterinary and Animal Sciences, University of Chile, Santiago 8820808, Chile
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Raditic DM, Bartges JW. Evidence-based Integrative Medicine in Clinical Veterinary Oncology. Vet Clin North Am Small Anim Pract 2014; 44:831-53. [DOI: 10.1016/j.cvsm.2014.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Barnard RA, Wittenburg LA, Amaravadi RK, Gustafson DL, Thorburn A, Thamm DH. Phase I clinical trial and pharmacodynamic evaluation of combination hydroxychloroquine and doxorubicin treatment in pet dogs treated for spontaneously occurring lymphoma. Autophagy 2014; 10:1415-25. [PMID: 24991836 DOI: 10.4161/auto.29165] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a lysosomal degradation process that may act as a mechanism of survival in a variety of cancers. While pharmacologic inhibition of autophagy with hydroxychloroquine (HCQ) is currently being explored in human clinical trials, it has never been evaluated in canine cancers. Non-Hodgkin lymphoma (NHL) is one of the most prevalent tumor types in dogs and has similar pathogenesis and response to treatment as human NHL. Clinical trials in canine patients are conducted in the same way as in human patients, thus, to determine a maximum dose of HCQ that can be combined with a standard chemotherapy, a Phase I, single arm, dose escalation trial was conducted in dogs with spontaneous NHL presenting as patients to an academic, tertiary-care veterinary teaching hospital. HCQ was administered daily by mouth throughout the trial, beginning 72 h prior to doxorubicin (DOX), which was given intravenously on a 21-d cycle. Peripheral blood mononuclear cells and biopsies were collected before and 3 d after HCQ treatment and assessed for autophagy inhibition and HCQ concentration. A total of 30 patients were enrolled in the trial. HCQ alone was well tolerated with only mild lethargy and gastrointestinal-related adverse events. The overall response rate (ORR) for dogs with lymphoma was 93.3%, with median progression-free interval (PFI) of 5 mo. Pharmacokinetic analysis revealed a 100-fold increase in HCQ in tumors compared with plasma. There was a trend that supported therapy-induced increase in LC3-II (the cleaved and lipidated form of microtubule-associated protein 1 light chain 3/LC3, which serves as a maker for autophagosomes) and SQSTM1/p62 (sequestosome 1) after treatment. The superior ORR and comparable PFI to single-agent DOX provide strong support for further evaluation via randomized, placebo-controlled trials in canine and human NHL.
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Affiliation(s)
- Rebecca A Barnard
- Department of Clinical Sciences; Colorado State University; Fort Collins, CO USA
| | - Luke A Wittenburg
- Department of Clinical Sciences; Colorado State University; Fort Collins, CO USA
| | - Ravi K Amaravadi
- Department of Medicine Hematology Oncology Division; Pearlman School of Medicine; University of Pennsylvania; Philadelphia, PA USA
| | - Daniel L Gustafson
- Department of Clinical Sciences; Colorado State University; Fort Collins, CO USA
| | - Andrew Thorburn
- Department of Pharmacology; University of Colorado School of Medicine; Aurora, CO USA
| | - Douglas H Thamm
- Department of Clinical Sciences; Colorado State University; Fort Collins, CO USA
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8
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Théon A, Pusterla N, Magdesian K, Wittenburg L, Marmulak T, Wilson W. A Pilot Phase II Study of the Efficacy and Biosafety of Doxorubicin Chemotherapy in Tumor-Bearing Equidae. J Vet Intern Med 2013; 27:1581-8. [DOI: 10.1111/jvim.12144] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 04/15/2013] [Accepted: 06/05/2013] [Indexed: 11/28/2022] Open
Affiliation(s)
- A.P. Théon
- Department of Surgery and Radiology; School of Veterinary Medicine; University of California; Davis CA
| | - N. Pusterla
- Department of Medicine and Epidemiology ; School of Veterinary Medicine; University of California; Davis CA
| | - K.G. Magdesian
- Department of Medicine and Epidemiology ; School of Veterinary Medicine; University of California; Davis CA
| | - L. Wittenburg
- Department of Clinical Sciences; Veterinary Medical Center; Pharmacology Core Facility; Colorado State University; Fort Collins CO
| | - T. Marmulak
- Department of Medicine and Epidemiology ; School of Veterinary Medicine; University of California; Davis CA
| | - W.D. Wilson
- Department of Medicine and Epidemiology ; School of Veterinary Medicine; University of California; Davis CA
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9
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Lenox CE, Bauer JE. Potential adverse effects of omega-3 Fatty acids in dogs and cats. J Vet Intern Med 2013; 27:217-26. [PMID: 23323770 DOI: 10.1111/jvim.12033] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/09/2012] [Accepted: 11/21/2012] [Indexed: 11/29/2022] Open
Abstract
Fish oil omega-3 fatty acids, mainly eicosapentaenoic acid and docosahexaenoic acid, are used in the management of several diseases in companion animal medicine, many of which are inflammatory in nature. This review describes metabolic differences among omega-3 fatty acids and outlines potential adverse effects that may occur with their supplementation in dogs and cats with a special focus on omega-3 fatty acids from fish oil. Important potential adverse effects of omega-3 fatty acid supplementation include altered platelet function, gastrointestinal adverse effects, detrimental effects on wound healing, lipid peroxidation, potential for nutrient excess and toxin exposure, weight gain, altered immune function, effects on glycemic control and insulin sensitivity, and nutrient-drug interactions.
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Affiliation(s)
- C E Lenox
- Gulf Coast Veterinary Specialists, Houston, TX 77027, USA.
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Wittenburg LA, Thamm DH, Gustafson DL. Development of a limited-sampling model for prediction of doxorubicin exposure in dogs. Vet Comp Oncol 2012; 12:114-9. [PMID: 22747489 DOI: 10.1111/j.1476-5829.2012.00340.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 05/01/2012] [Accepted: 06/07/2012] [Indexed: 11/28/2022]
Abstract
Understanding the relationship between drug dose and exposure (pharmacokinetics, PK) and the relationship between exposure and effect (pharmacodynamics) is an important component of pharmacology when attempting to predict clinical effects of anticancer drugs. PK studies can provide a better understanding of these relationships; however, they often involve intensive sampling over an extended period of time, resulting in increased cost and decreased compliance. Doxorubicin (DOX), one of the most widely used antineoplastic agents in veterinary cancer therapy, is characterized by large interpatient variability in overall drug exposure and the development and degree of myelosuppression following equivalent dosages. We have developed and validated a limited-sampling strategy for DOX, in which three blood samples are obtained over 1 h post-treatment, that accurately predicts patient exposure. This strategy could allow for refining of dosing variables and utilization of therapeutic drug monitoring to ensure optimized dosing.
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Affiliation(s)
- L A Wittenburg
- Department of Clinical Sciences, Colorado State University Animal Cancer Center, Fort Collins, CO, USA
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Wittenburg LA, Gustafson DL, Thamm DH. Phase I pharmacokinetic and pharmacodynamic evaluation of combined valproic acid/doxorubicin treatment in dogs with spontaneous cancer. Clin Cancer Res 2010; 16:4832-42. [PMID: 20705615 DOI: 10.1158/1078-0432.ccr-10-1238] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE Histone deacetylase inhibitors (HDACi) are targeted anticancer agents with a well-documented ability to act synergistically with cytotoxic agents. We recently showed that the HDACi valproic acid sensitizes osteosarcoma cells to doxorubicin in vitro and in vivo. As there are no published reports on the clinical utility of HDACi in dogs with spontaneous cancers, we sought to determine a safe and biologically effective dose of valproic acid administered prior to a standard dose of doxorubicin. METHODS Twenty-one dogs were enrolled into eight cohorts in an accelerated dose-escalation trial consisting of pretreatment with oral valproic acid followed by doxorubicin on a three-week cycle. Blood and tumor tissue were collected for determination of serum valproic acid concentration and evaluation of pharmacodynamic effects by immunofluorescence cytochemistry and immunohistochemistry. Serum and complete blood counts were obtained for determination of changes in doxorubicin pharmacokinetics or hematologic effects. RESULTS All doses of valproic acid were well tolerated. Serum valproic acid concentrations increased linearly with dose. Doxorubicin pharmacokinetics were comparable with those in dogs receiving doxorubicin alone. A positive correlation was detected between valproic acid dose and histone hyperacetylation in peripheral blood mononuclear cells. No potentiation of doxorubicin-induced myelosuppression was observed. Histone hyperacetylation was documented in tumor and peripheral blood mononuclear cells. Responses included 2 of 21 complete, 3 of 21 partial, 5 of 21 stable disease, and 11 of 21 progressive disease. CONCLUSIONS Valproic acid can be administered to dogs at doses up to 240 mg/kg/day prior to a standard dose of doxorubicin. In addition, we have developed the pharmacokinetic/pharmacodynamic tools necessary for future studies of novel HDACi in the clinical setting of canine cancer.
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Affiliation(s)
- Luke A Wittenburg
- Animal Cancer Center, Department of Clinical Sciences, Colorado State University Animal Cancer Center, Fort Collins, USA.
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Gustafson DL, Thamm DH. Pharmacokinetic modeling of doxorubicin pharmacokinetics in dogs deficient in ABCB1 drug transporters. J Vet Intern Med 2010; 24:579-86. [PMID: 20337920 DOI: 10.1111/j.1939-1676.2010.0496.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The identification of dogs defective in ATP-binding cassette transporter B1 (ABCB1, MDR1) activity has prompted questions regarding pharmacokinetics (PK), efficacy and toxicity of ABCB1 substrates in these dogs. HYPOTHESIS/OBJECTIVES Dogs defective in ABCB1 activity (ABCB1(null)) have doxorubicin (DOX) PK different from that of normal dogs (ABCB1(wt)). Utilization of a physiologically based pharmacokinetic (PBPK) model allows computer simulation to study this polymorphism's impact on DOX PK. ANIMALS None. METHODS A virtual ABCB1(wt) dog population was generated and DOX distribution, elimination, and metabolism simulated by PBPK modeling. An in silico population of virtual dogs was generated by Monte Carlo simulation, with variability in physiologic and biochemical parameters consistent with the dog population. This population was used in the PBPK model. The ABCB1 components of the model were inactivated to generate an ABCB1(null) population and simulations repeated at multiple doses. Resulting DOX levels were used to generate PK parameters. RESULTS DOX exposures in the ABCB1(null) population were increased in all simulated tissues including serum (24%) and gut (174%). Estimated dosages in the ABCB1(null) population to approximate exposure in the ABCB1(wt) population at a dose of 30 mg/m(2) were 24.8 +/- 3.5 mg/m(2) for serum and 10.7 +/- 5.9 mg/m(2) for gut. CONCLUSIONS AND CLINICAL IMPORTANCE These results suggest that serum DOX concentrations are not indicative of tissue exposure, especially those with appreciable ABCB1 activity, and that gastrointestinal (GI) toxicosis would be dose limiting in ABCB1(null) populations. Dosage reductions necessary to prevent GI toxicosis likely result in subtherapeutic concentrations, thereby reducing DOXs efficacy in ABCB1(null) dogs.
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Affiliation(s)
- D L Gustafson
- Department of Clinical Sciences, and the Animal Cancer Center, Colorado State University, Fort Collins, CO 80523-1620, USA.
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Knobloch A, Mohring S, Eberle N, Nolte I, Hamscher G, Simon D. Drug Residues in Serum of Dogs Receiving Anticancer Chemotherapy. J Vet Intern Med 2010; 24:379-83. [DOI: 10.1111/j.1939-1676.2009.0469.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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