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 γ-secretase inhibitor that reduces amyloid-β (Aβ) production with an in vitro IC50 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 EC50 of 2.1 μM. A single acute dose showed dose-dependent reduction in brain, cerebrospinal fluid (CSF), and plasma Aβ 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 Aβ. To further characterize Aβ 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 Aβ, and the magnitude and duration of Aβ lowering exceeded those of the reductions in B-cell endpoints. Other γ-secretase inhibitors have shown high potency at elevating Aβ 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 Aβ11-40 and Aβ1-43 at doses that potently inhibited Aβ1-40 and Aβ1-42. PF-3084014, like previously described γ-secretase inhibitors, preferentially reduced Aβ1-40 relative to Aβ1-42. Potency at Aβ relative to Notch-related endpoints in vitro and in vivo suggests that a therapeutic index can be achieved with this compound.
Footnotes
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.167379.
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
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ABBREVIATIONS:
- 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
- Aβ
- amyloid-β
- APP
- amyloid precursor protein
- FTOC
- fetal thymic organ culture
- IP
- immunoprecipitation
- MS
- mass spectrometry
- MALDI
- matrix-assisted laser desorption/ionization
- CSF
- cerebrospinal fluid
- LY-450139
- (S)-2-hydroxy-3-methyl-N-[(S)-1-((S)-3-methyl-2-oxo-2,3,4,5,-tetrahydro-1H-benzo[d]azepin-1-carbamoyl)-ethyl]-butyramide
- LY-411575
- N2-[(2S)-2-(3,5-difluorophenyl)-2-hydroxyethanoyl]-N1-[(7S)-5-methyl-6-oxo-6,7-dihydro-5H-dibenzo[b,d]azepin-7-yl]-l-alaninamide
- ELISA
- enzyme-linked immunosorbent assay
- DELFIA
- dissociation-enhanced lanthanide fluorescent immunoassay
- FBS
- fetal bovine serum
- FITC
- fluorescein isothiocyanate
- FACS
- fluorescence-activated cell sorting
- APC
- allophycocyanin
- PBS
- phosphate-buffered saline
- DAPT
- N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester.
- Received February 17, 2010.
- Accepted April 1, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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