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Liang SH, Chen JM, Normandin MD, Chang JS, Chang GC, Taylor CK, Trapa P, Plummer MS, Para KS, Conn EL, Lopresti‐Morrow L, Lanyon LF, Cook JM, Richter KEG, Nolan CE, Schachter JB, Janat F, Che Y, Shanmugasundaram V, Lefker BA, Enerson BE, Livni E, Wang L, Guehl NJ, Patnaik D, Wagner FF, Perlis R, Holson EB, Haggarty SJ, El Fakhri G, Kurumbail RG, Vasdev N. Discovery of a Highly Selective Glycogen Synthase Kinase‐3 Inhibitor (PF‐04802367) That Modulates Tau Phosphorylation in the Brain: Translation for PET Neuroimaging. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Steven H. Liang
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Jinshan Michael Chen
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Marc D. Normandin
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Jeanne S. Chang
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - George C. Chang
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Christine K. Taylor
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Patrick Trapa
- Pfizer Worldwide Research and Development 610 Main Street Cambridge MA 02139 USA
| | - Mark S. Plummer
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Kimberly S. Para
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Edward L. Conn
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Lori Lopresti‐Morrow
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Lorraine F. Lanyon
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - James M. Cook
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Karl E. G. Richter
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Charlie E. Nolan
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Joel B. Schachter
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Fouad Janat
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Ye Che
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | | | - Bruce A. Lefker
- Pfizer Worldwide Research and Development 610 Main Street Cambridge MA 02139 USA
| | - Bradley E. Enerson
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Elijahu Livni
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Lu Wang
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Nicolas J. Guehl
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Debasis Patnaik
- Departments of Neurology & Psychiatry Massachusetts General Hospital Harvard Medical School 185 Cambridge Street Boston MA 02114 USA
| | - Florence F. Wagner
- Stanley Center for Psychiatric Research Broad Institute 415 Main Street Cambridge MA o2142 USA
| | - Roy Perlis
- Stanley Center for Psychiatric Research Broad Institute 415 Main Street Cambridge MA o2142 USA
- Departments of Neurology & Psychiatry Massachusetts General Hospital Harvard Medical School 185 Cambridge Street Boston MA 02114 USA
| | - Edward B. Holson
- Stanley Center for Psychiatric Research Broad Institute 415 Main Street Cambridge MA o2142 USA
| | - Stephen J. Haggarty
- Departments of Neurology & Psychiatry Massachusetts General Hospital Harvard Medical School 185 Cambridge Street Boston MA 02114 USA
| | - Georges El Fakhri
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
| | - Ravi G. Kurumbail
- Pfizer Worldwide Research and Development, Groton Laboratories Eastern Point Road Groton CT 06340 USA
| | - Neil Vasdev
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging Massachusetts General Hospital & Department of Radiology Harvard Medical School Boston MA 02114 USA
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Liang SH, Chen JM, Normandin MD, Chang JS, Chang GC, Taylor CK, Trapa P, Plummer MS, Para KS, Conn EL, Lopresti-Morrow L, Lanyon LF, Cook JM, Richter KEG, Nolan CE, Schachter JB, Janat F, Che Y, Shanmugasundaram V, Lefker BA, Enerson BE, Livni E, Wang L, Guehl NJ, Patnaik D, Wagner FF, Perlis R, Holson EB, Haggarty SJ, El Fakhri G, Kurumbail RG, Vasdev N. Discovery of a Highly Selective Glycogen Synthase Kinase-3 Inhibitor (PF-04802367) That Modulates Tau Phosphorylation in the Brain: Translation for PET Neuroimaging. Angew Chem Int Ed Engl 2016; 55:9601-5. [PMID: 27355874 PMCID: PMC4983481 DOI: 10.1002/anie.201603797] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [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: 04/19/2016] [Indexed: 11/09/2022]
Abstract
Glycogen synthase kinase-3 (GSK-3) regulates multiple cellular processes in diabetes, oncology, and neurology. N-(3-(1H-1,2,4-triazol-1-yl)propyl)-5-(3-chloro-4-methoxyphenyl)oxazole-4-carboxamide (PF-04802367 or PF-367) has been identified as a highly potent inhibitor, which is among the most selective antagonists of GSK-3 to date. Its efficacy was demonstrated in modulation of tau phosphorylation in vitro and in vivo. Whereas the kinetics of PF-367 binding in brain tissues are too fast for an effective therapeutic agent, the pharmacokinetic profile of PF-367 is ideal for discovery of radiopharmaceuticals for GSK-3 in the central nervous system. A (11) C-isotopologue of PF-367 was synthesized and preliminary PET imaging studies in non-human primates confirmed that we have overcome the two major obstacles for imaging GSK-3, namely, reasonable brain permeability and displaceable binding.
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Affiliation(s)
- Steven H Liang
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Jinshan Michael Chen
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Marc D Normandin
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Jeanne S Chang
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - George C Chang
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Christine K Taylor
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Patrick Trapa
- Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA, 02139, USA
| | - Mark S Plummer
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Kimberly S Para
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Edward L Conn
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Lori Lopresti-Morrow
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Lorraine F Lanyon
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - James M Cook
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Karl E G Richter
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Charlie E Nolan
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Joel B Schachter
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Fouad Janat
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Ye Che
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Veerabahu Shanmugasundaram
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Bruce A Lefker
- Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA, 02139, USA
| | - Bradley E Enerson
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA
| | - Elijahu Livni
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Lu Wang
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Nicolas J Guehl
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Debasis Patnaik
- Departments of Neurology & Psychiatry, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA, 02114, USA
| | - Florence F Wagner
- Stanley Center for Psychiatric Research, Broad Institute, 415 Main Street, Cambridge, MA, o2142, USA
| | - Roy Perlis
- Stanley Center for Psychiatric Research, Broad Institute, 415 Main Street, Cambridge, MA, o2142, USA
- Departments of Neurology & Psychiatry, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA, 02114, USA
| | - Edward B Holson
- Stanley Center for Psychiatric Research, Broad Institute, 415 Main Street, Cambridge, MA, o2142, USA
| | - Stephen J Haggarty
- Departments of Neurology & Psychiatry, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA, 02114, USA
| | - Georges El Fakhri
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Ravi G Kurumbail
- Pfizer Worldwide Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT, 06340, USA.
| | - Neil Vasdev
- Gordon Center for Medical Imaging & Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA.
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Brodney MA, Auperin DD, Becker SL, Bronk BS, Brown TM, Coffman KJ, Finley JE, Hicks CD, Karmilowicz MJ, Lanz TA, Liston D, Liu X, Martin BA, Nelson RB, Nolan CE, Oborski CE, Parker CP, Richter KEG, Pozdnyakov N, Sahagan BG, Schachter JB, Sokolowski SA, Tate B, Wood DE, Wood KM, Van Deusen JW, Zhang L. Design, synthesis, and in vivo characterization of a novel series of tetralin amino imidazoles as γ-secretase inhibitors: discovery of PF-3084014. Bioorg Med Chem Lett 2010; 21:2637-40. [PMID: 21269827 DOI: 10.1016/j.bmcl.2010.12.118] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 12/12/2022]
Abstract
A novel series of tetralin containing amino imidazoles, derived from modification of the corresponding phenyl acetic acid derivatives is described. Replacement of the amide led to identification of a potent series of tetralin-amino imidazoles with robust central efficacy. The reduction of brain Aβ in guinea pigs in the absence of changes in B-cells suggested a potential therapeutic index with respect to APP processing compared with biomarkers of notch related toxicity. Optimization of the FTOC to plasma concentrations at the brain Aβ EC(50) lead to the identification of compound 14f (PF-3084014) which was selected for clinical development.
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Affiliation(s)
- Michael A Brodney
- Neuroscience Medicinal Chemistry, Pfizer PharmaTherapeutics Research and Development, Eastern Point Road, Groton, CT 06340, USA.
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4
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Lanz TA, Wood KM, Richter KEG, Nolan CE, Becker SL, Pozdnyakov N, Martin BA, Du P, Oborski CE, Wood DE, Brown TM, Finley JE, Sokolowski SA, Hicks CD, Coffman KJ, Geoghegan KF, Brodney MA, Liston D, Tate B. Pharmacodynamics and pharmacokinetics of the gamma-secretase inhibitor PF-3084014. J Pharmacol Exp Ther 2010; 334:269-77. [PMID: 20363853 DOI: 10.1124/jpet.110.167379] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PF-3084014 [(S)-2-((S)-5,7-difluoro-1,2,3,4-tetrahydronaphthalen-3-ylamino)-N-(1-(2-methyl-1-(neopentylamino)propan-2-yl)-1H-imidazol-4-yl)pentanamide] is a novel gamma-secretase inhibitor that reduces amyloid-beta (Abeta) production with an in vitro IC(50) of 1.2 nM (whole-cell assay) to 6.2 nM (cell-free assay). This compound inhibits Notch-related T- and B-cell maturation in an in vitro thymocyte assay with an EC(50) of 2.1 microM. A single acute dose showed dose-dependent reduction in brain, cerebrospinal fluid (CSF), and plasma Abeta in Tg2576 mice as measured by enzyme-linked immunosorbent assay and immunoprecipitation (IP)/mass spectrometry (MS). Guinea pigs were dosed with PF-3084014 for 5 days via osmotic minipump at 0.03 to 3 mg/kg/day and exhibited dose-dependent reduction in brain, CSF, and plasma Abeta. To further characterize Abeta dynamics in brain, CSF, and plasma in relation to drug exposure and Notch-related toxicities, guinea pigs were dosed with 0.03 to 10 mg/kg PF-3084014, and tissues were collected at regular intervals from 0.75 to 30 h after dose. Brain, CSF, and plasma all exhibited dose-dependent reductions in Abeta, and the magnitude and duration of Abeta lowering exceeded those of the reductions in B-cell endpoints. Other gamma-secretase inhibitors have shown high potency at elevating Abeta in the conditioned media of whole cells and the plasma of multiple animal models and humans. Such potentiation was not observed with PF-3084014. IP/MS analysis, however, revealed dose-dependent increases in Abeta11-40 and Abeta1-43 at doses that potently inhibited Abeta1-40 and Abeta1-42. PF-3084014, like previously described gamma-secretase inhibitors, preferentially reduced Abeta1-40 relative to Abeta1-42. Potency at Abeta relative to Notch-related endpoints in vitro and in vivo suggests that a therapeutic index can be achieved with this compound.
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Affiliation(s)
- Thomas A Lanz
- Neuroscience Research Unit, Pfizer, Inc., Groton, CT 06340, USA.
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6
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Lanz TA, Salatto CT, Semproni AR, Marconi M, Brown TM, Richter KEG, Schmidt K, Nelson FR, Schachter JB. Peripheral elevation of IGF-1 fails to alter Abeta clearance in multiple in vivo models. Biochem Pharmacol 2007; 75:1093-103. [PMID: 18076866 DOI: 10.1016/j.bcp.2007.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 10/31/2007] [Accepted: 11/05/2007] [Indexed: 10/22/2022]
Abstract
Increasing beta-amyloid (Abeta) clearance may alter the course of Alzheimer's disease progression and attenuate amyloid plaque pathology. Insulin-like growth factor I (IGF-1) augmentation has been suggested to increase Abeta clearance by facilitating transport of Abeta out of the brain. The availability of safe agents that increase IGF-1 levels therefore makes IGF-1 elevation an attractive target for disease modifying therapy in AD. The present series of studies sought to replicate published paradigms in which peripheral IGF-1 administration lowered brain Abeta acutely, with reduction in plaque pathology after chronic treatment. Thus Abeta levels were measured in several animal models following treatments that elevated IGF-1. Administration of IGF-1 to young or old rats for up to 3 days had no effect on Abeta levels in brain, CSF, or plasma. In adult beagles, 4 days of dosing with the growth hormone secretagogue, CP-424391, doubled baseline plasma IGF-1 levels, yet failed to alter CSF or plasma Abeta. 5-day treatment of young Tg2576 mice with IGF-1 produced robust elevations of IGF-1 levels in plasma, but no effects on Abeta were detected in brain, CSF, or plasma. Finally, 11-month-old Tg2576 mice were implanted with subcutaneous minipumps delivering IGF-1 for 1 month. No significant changes in Abeta (by ELISA or Western blot), plaque pathology, or phospho-tau epitopes were detected. These results do not demonstrate acute or chronic actions of peripherally administered IGF-1 on Abeta levels or the phosphorylation state of tau and therefore do not suggest any disease-modifying benefits of IGF-1 restorative therapy for AD through these mechanisms.
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Affiliation(s)
- Thomas A Lanz
- CNS Discovery, Pfizer, Inc., Eastern Point Road, Groton, CT 06340, United States.
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Planel E, Richter KEG, Nolan CE, Finley JE, Liu L, Wen Y, Krishnamurthy P, Herman M, Wang L, Schachter JB, Nelson RB, Lau LF, Duff KE. Anesthesia leads to tau hyperphosphorylation through inhibition of phosphatase activity by hypothermia. J Neurosci 2007; 27:3090-7. [PMID: 17376970 PMCID: PMC6672474 DOI: 10.1523/jneurosci.4854-06.2007] [Citation(s) in RCA: 278] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Postoperative cognitive dysfunction, confusion, and delirium are common after general anesthesia in the elderly, with symptoms persisting for months or years in some patients. Even middle-aged patients are likely to have postoperative cognitive dysfunction for months after surgery, and Alzheimer's disease (AD) patients appear to be particularly at risk of deterioration after anesthesia. Several investigators have thus examined whether general anesthesia is associated with AD, with some studies suggesting that exposure to anesthetics may increase the risk of AD. However, little is known on the biochemical consequences of anesthesia on pathogenic pathways in vivo. Here, we investigated the effect of anesthesia on tau phosphorylation and amyloid precursor protein (APP) metabolism in mouse brain. We found that, regardless of the anesthetic used, anesthesia induced rapid and massive hyperphosphorylation of tau, rapid and prolonged hypothermia, inhibition of Ser/Thr PP2A (protein phosphatase 2A), but no changes in APP metabolism or Abeta (beta-amyloid peptide) accumulation. Reestablishing normothermia during anesthesia completely rescued tau phosphorylation to normal levels. Our results indicate that changes in tau phosphorylation were not a result of anesthesia per se, but a consequence of anesthesia-induced hypothermia, which led to inhibition of phosphatase activity and subsequent hyperphosphorylation of tau. These findings call for careful monitoring of core temperature during anesthesia in laboratory animals to avoid artifactual elevation of protein phosphorylation. Furthermore, a thorough examination of the effect of anesthesia-induced hypothermia on the risk and progression of AD is warranted.
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Affiliation(s)
- Emmanuel Planel
- Columbia University Medical Center, Department of Pathology, Taub Institute for Alzheimer's Disease Research, New York, New York 10032, USA.
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Lanz TA, Karmilowicz MJ, Wood KM, Pozdnyakov N, Du P, Piotrowski MA, Brown TM, Nolan CE, Richter KEG, Finley JE, Fei Q, Ebbinghaus CF, Chen YL, Spracklin DK, Tate B, Geoghegan KF, Lau LF, Auperin DD, Schachter JB. Concentration-dependent modulation of amyloid-beta in vivo and in vitro using the gamma-secretase inhibitor, LY-450139. J Pharmacol Exp Ther 2006; 319:924-33. [PMID: 16920992 DOI: 10.1124/jpet.106.110700] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
LY-450139 is a gamma-secretase inhibitor shown to have efficacy in multiple cellular and animal models. Paradoxically, robust elevations of plasma amyloid-beta (Abeta) have been reported in dogs and humans after administration of subefficacious doses. The present study sought to further evaluate Abeta responses to LY-450139 in the guinea pig, a nontransgenic model that has an Abeta sequence identical to that of human. Male guinea pigs were treated with LY-450139 (0.2-60 mg/kg), and brain, cerebrospinal fluid, and plasma Abeta levels were characterized at 1, 3, 6, 9, and 14 h postdose. Low doses significantly elevated plasma Abeta levels at early time points, with return to baseline within hours. Higher doses inhibited Abeta levels in all compartments at early time points, but elevated plasma Abeta levels at later time points. To determine whether this phenomenon occurs under steady-state drug exposure, guinea pigs were implanted with subcutaneous minipumps delivering LY-450139 (0.3-30 mg/kg/day) for 5 days. Plasma Abeta was significantly inhibited at 10-30 mg/kg/day, but significantly elevated at 1 mg/kg/day. To further understand the mechanism of Abeta elevation by LY-450139, H4 cells overexpressing the Swedish mutant of amyloid-precursor protein and a mouse embryonic stem cell-derived neuronal cell line were studied. In both cellular models, elevated levels of secreted Abeta were observed at subefficacious concentrations, whereas dose-responsive inhibition was observed at higher concentrations. These results suggest that LY-450139 modulates the gamma-secretase complex, eliciting Abeta lowering at high concentrations but Abeta elevation at low concentrations.
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Affiliation(s)
- Thomas A Lanz
- Pfizer, Inc., Eastern Point Rd., MS# 8220-4183, Groton, CT 06340, USA.
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