- Email: [email protected]
APP-selective gamma secretase inhibitor ELND006 effects on brain parenchymal and vascular amyloid beta in the PDAPP mouse model of Alzheimer's disease
S546
Poster Presentations P3
activation state markers, YM1 and arginase-1. We were unable to make the same observation in mice over-expressing CCL5, suggesting that these chemokines might play different roles in activating endogenous microglia and/ or attracting exogenous cells of monocytic origin. Next, we will investigate the efficacy of the different chemokines over-expressed by AAV-9 in increasing the infiltration of GFP labeleld peripheral bone marrow derived monocytes (selected by CD11b+ expression). Conclusions: Overall, these experiments will attempt to identify conditions enhancing infiltration of circulating monocytes to evaluate their role in modifying the pathogenesis in AD. Furthermore, the phenotypic characterization of these cells will assess the multiple microglial markers associated with the M1 or M2 activation state.
P3-320
PHARMACOKINETIC AND PHARMACODYNAMIC INVESTIGATION OF ELND006, A NOVEL APP-SELECTIVE GAMMA-SECRETASE INHIBITOR, ON AMYLOID-b CONCENTRATIONS IN THE BRAIN, CSF AND PLASMA OF MULTIPLE NONCLINICAL SPECIES FOLLOWING ORAL ADMINISTRATION
Elizabeth Brigham, Kevin Quinn, Grace Kwong, Chris Willits, Erich Goldbach, Ruth Motter, Michael Lee, Kang Hu, William Wallace, Dora Kholodenko, Pearl Tang-Tanaka, Huifang Ni, Susanna Hemphill, Xiao-hua Chen, Tovah Eichenbaum, Lany Ruslim, Lan Nguyen, Pamela Santiago, Anna Liao, Michael Bova, Gary Probst, Michael Dappen, Jacek Jagodzinski, Guriqbal Basi, Daniel Ness, Elan Pharmaceuticals, South San Francisco, CA, USA. Contact e-mail: [email protected] Background: Sequential processing of the beta-amyloid precursor protein (APP) by beta-secretase and gamma-secretase produces Ab, a peptide that is central to the pathogenesis of Alzheimer’s disease. We have identified novel gamma-secretase inhibitors which demonstrate in vitro substrate selectivity towards inhibiting APP cleavage compared to Notch. ELND006 is one of these potent inhibitors and is currently being evaluated in Phase 1 human clinical trials. We present here the in vivo characterization of ELND006 after oral administration in multiple preclinical models. Methods: The potency of ELND006 for inhibiting Ab production resulting from gamma-secretase-mediated cleavage of APP and the selectivity of ELND006 for inhibition of APP cleavage compared to Notch cleavage was determined in enzymatic and cellular assays. Ab and compound levels were analyzed in the brain, CSF and/or plasma of FVB wildtype mice, PDAPP mice, Sprague Dawley rats and Hartley Guinea pigs after single or repeat dose oral administration of ELND006 or vehicle. Compound levels were determined by an LC-MS/MS assay. Ab levels (1-x, x-40 or x-42) were determined by an ELISA assay. Results: ELND006 inhibited APP and Notch cleavage with an IC50 ¼ 0.34 nM and 5.3 nM respectively. ELND006 inhibited Ab production and Notch signaling in cells with an IC50 ¼ 1.1 nM and 81.6 nM respectively. After oral administration of ELND006 in multiple species, ELND006 penetrated the brain (Kp > 1) and significantly reduced brain and CSF Ab at doses between 0.3 to 30 mg/kg. In all species tested, plasma ELND006 concentrations needed to reduce plasma Ab were higher than those needed to reduce brain Ab. Elevated plasma Ab was observed under some ELND006 treatment conditions, consistent with results achieved with other gamma-secretase inhibitors. Plasma ELND006 concentrations of 8-35 ng/mL were associated with lowering of Ab in the brain of approximately 25%. Conclusions: ELND006 is a potent, APP-selective gamma-secretase inhibitor and is approximately 15- to 70-fold more selective towards inhibiting gammasecretase mediated cleavage of APP than Notch cleavage. ELND006 plasma concentrations required to reduce brain Ab were highly consistent across species, offering an opportunity to translate these nonclinical data into a clinical setting. Phase 1 clinical trials with ELND006 are in progress.
P3-321
APP-SELECTIVE GAMMA SECRETASE INHIBITOR ELND006 EFFECTS ON BRAIN PARENCHYMAL AND VASCULAR AMYLOID BETA IN THE PDAPP MOUSE MODEL OF ALZHEIMER’S DISEASE
Sally Schroeter, Elizabeth Brigham, Ruth Motter, Chris Nishioka, Terry Guido, Karen Khan, Dora Kholodenko, Pearl Tanaka, Ferdie Soriano, Kevin Quinn, Erich Goldbach, Dora Games, Daniel Ness, Elan Pharmaceuticals, South San Francisco, CA, USA. Contact e-mail: sally.schroeter@ elan.com Background: Cleavage of amyloid precursor protein (APP) by beta and gamma secretases produces amyloid beta (Abeta), a protein with neurotoxic properties that accumulates in the hallmark plaque pathologies of Alzheimer’s disease (AD). An APP-selective gamma secretase inhibitor, ELND006, was tested to determine efficacy in reducing Abeta-associated pathologies in aged PDAPP mice. Methods: Twelve month-old mice (limited, but established pathology) were treated with 2 mg/kg QD or BID for 13 weeks, and with 12.5 mg/kg/day QD for 13 and 26 weeks. Dosing paradigms were previously shown to reduce brain Abeta 25% to >50% for partial or full days in non-plaque-bearing PDAPP mice. Brain Abeta 1-x and x-42 levels were determined by ELISA. Leptomeningeal vascular and parenchymal amyloid burden(compact and diffuse) and neuritic dystrophy were assessed by Abeta and APP immunohistochemistry. Results: Treatment with 12.5 mg/kg/day for 13 weeks significantly reduced hippocampal amyloid burden and brain Abeta as measured by ELISA. Hippocampal neuritic burden, a measure of dystrophic neuronal response to compacted Abeta plaques and therefore an indirect measure of this plaque subtype, was not significantly reduced. However, a significant change in density of neuritic sites indicated an early effect on dystrophic neurites, consistent with a reduction in the number of small neuritic sites. At the lower dose administered once or twice daily for 13 weeks, a downward trend in hippocampal amyloid burden and neuritic burden was observed, and vascular and cortical amyloid burden, and brain Abeta were not significantly reduced. After 26 weeks of treatment at 12.5 mg/kg/day, the only dose tested at this timepoint, cortical and vascular amyloid burden and hippocampal neuritic burden were significantly reduced. There was a trend toward a decrease in brain Abeta as measured by ELISA. Conclusions: ELND006 effectively decreased the formation of, or prevented Abeta pathologies in the PDAPP mouse as assessed by histopathology and ELISA measures. These results support that a strategy for inhibiting gamma secretase may be efficacious in the treatment of AD and also of cerebral amyloid angiopathy, which is present in most AD patients.
P3-322
EFFECTS OF SINGLE AND MULTIPLE DOSE ORAL ADMINISTRATION OF ELND006, A NOVEL APPSELECTIVE GAMMA-SECRETASE INHIBITOR, ON AMYLOID-b CONCENTRATIONS IN THE BRAIN AND CSF OF CYNOMOLGUS MONKEYS
Elizabeth Brigham1, Kevin Quinn1, Ruth Motter1, Wherly Hoffman1, Erich Goldbach1, Dora Kholodenko1, Grace Kwong1, Chris Willits1, Gary Probst1, Jane Gunther1, Eric Adams2, John-Michael Sauer1, Gene Kinney1, Daniel Ness1, 1Elan Pharmaceuticals, South San Francisco, CA, USA; 2Northern Biomedical, Muskegon, MI, USA. Contact e-mail: beth. [email protected] Background: ELND006 is a potent, APP-selective gamma-secretase inhibitor currently being evaluated in Phase 1 human clinical trials. We present here the evaluation of ELND006 1) repeat-dose effects on beta-amyloid (Ab) levels in the brain, CSF and plasma of cynomolgus monkeys enrolled in nonclinical safety studies and 2) single-dose effects on Ab levels in the CSF and plasma of lumbar cannulated cynomolgus monkeys. Methods: For repeat-dose toxicology studies, cynomolgus monkeys were administered ELND006 once daily by oral gavage for 3 months. Brain, CSF and plasma samples were collected at termination, approximately 24 hours after the
Poster Presentations P3
activation state markers, YM1 and arginase-1. We were unable to make the same observation in mice over-expressing CCL5, suggesting that these chemokines might play different roles in activating endogenous microglia and/ or attracting exogenous cells of monocytic origin. Next, we will investigate the efficacy of the different chemokines over-expressed by AAV-9 in increasing the infiltration of GFP labeleld peripheral bone marrow derived monocytes (selected by CD11b+ expression). Conclusions: Overall, these experiments will attempt to identify conditions enhancing infiltration of circulating monocytes to evaluate their role in modifying the pathogenesis in AD. Furthermore, the phenotypic characterization of these cells will assess the multiple microglial markers associated with the M1 or M2 activation state.
P3-320
PHARMACOKINETIC AND PHARMACODYNAMIC INVESTIGATION OF ELND006, A NOVEL APP-SELECTIVE GAMMA-SECRETASE INHIBITOR, ON AMYLOID-b CONCENTRATIONS IN THE BRAIN, CSF AND PLASMA OF MULTIPLE NONCLINICAL SPECIES FOLLOWING ORAL ADMINISTRATION
Elizabeth Brigham, Kevin Quinn, Grace Kwong, Chris Willits, Erich Goldbach, Ruth Motter, Michael Lee, Kang Hu, William Wallace, Dora Kholodenko, Pearl Tang-Tanaka, Huifang Ni, Susanna Hemphill, Xiao-hua Chen, Tovah Eichenbaum, Lany Ruslim, Lan Nguyen, Pamela Santiago, Anna Liao, Michael Bova, Gary Probst, Michael Dappen, Jacek Jagodzinski, Guriqbal Basi, Daniel Ness, Elan Pharmaceuticals, South San Francisco, CA, USA. Contact e-mail: [email protected] Background: Sequential processing of the beta-amyloid precursor protein (APP) by beta-secretase and gamma-secretase produces Ab, a peptide that is central to the pathogenesis of Alzheimer’s disease. We have identified novel gamma-secretase inhibitors which demonstrate in vitro substrate selectivity towards inhibiting APP cleavage compared to Notch. ELND006 is one of these potent inhibitors and is currently being evaluated in Phase 1 human clinical trials. We present here the in vivo characterization of ELND006 after oral administration in multiple preclinical models. Methods: The potency of ELND006 for inhibiting Ab production resulting from gamma-secretase-mediated cleavage of APP and the selectivity of ELND006 for inhibition of APP cleavage compared to Notch cleavage was determined in enzymatic and cellular assays. Ab and compound levels were analyzed in the brain, CSF and/or plasma of FVB wildtype mice, PDAPP mice, Sprague Dawley rats and Hartley Guinea pigs after single or repeat dose oral administration of ELND006 or vehicle. Compound levels were determined by an LC-MS/MS assay. Ab levels (1-x, x-40 or x-42) were determined by an ELISA assay. Results: ELND006 inhibited APP and Notch cleavage with an IC50 ¼ 0.34 nM and 5.3 nM respectively. ELND006 inhibited Ab production and Notch signaling in cells with an IC50 ¼ 1.1 nM and 81.6 nM respectively. After oral administration of ELND006 in multiple species, ELND006 penetrated the brain (Kp > 1) and significantly reduced brain and CSF Ab at doses between 0.3 to 30 mg/kg. In all species tested, plasma ELND006 concentrations needed to reduce plasma Ab were higher than those needed to reduce brain Ab. Elevated plasma Ab was observed under some ELND006 treatment conditions, consistent with results achieved with other gamma-secretase inhibitors. Plasma ELND006 concentrations of 8-35 ng/mL were associated with lowering of Ab in the brain of approximately 25%. Conclusions: ELND006 is a potent, APP-selective gamma-secretase inhibitor and is approximately 15- to 70-fold more selective towards inhibiting gammasecretase mediated cleavage of APP than Notch cleavage. ELND006 plasma concentrations required to reduce brain Ab were highly consistent across species, offering an opportunity to translate these nonclinical data into a clinical setting. Phase 1 clinical trials with ELND006 are in progress.
P3-321
APP-SELECTIVE GAMMA SECRETASE INHIBITOR ELND006 EFFECTS ON BRAIN PARENCHYMAL AND VASCULAR AMYLOID BETA IN THE PDAPP MOUSE MODEL OF ALZHEIMER’S DISEASE
Sally Schroeter, Elizabeth Brigham, Ruth Motter, Chris Nishioka, Terry Guido, Karen Khan, Dora Kholodenko, Pearl Tanaka, Ferdie Soriano, Kevin Quinn, Erich Goldbach, Dora Games, Daniel Ness, Elan Pharmaceuticals, South San Francisco, CA, USA. Contact e-mail: sally.schroeter@ elan.com Background: Cleavage of amyloid precursor protein (APP) by beta and gamma secretases produces amyloid beta (Abeta), a protein with neurotoxic properties that accumulates in the hallmark plaque pathologies of Alzheimer’s disease (AD). An APP-selective gamma secretase inhibitor, ELND006, was tested to determine efficacy in reducing Abeta-associated pathologies in aged PDAPP mice. Methods: Twelve month-old mice (limited, but established pathology) were treated with 2 mg/kg QD or BID for 13 weeks, and with 12.5 mg/kg/day QD for 13 and 26 weeks. Dosing paradigms were previously shown to reduce brain Abeta 25% to >50% for partial or full days in non-plaque-bearing PDAPP mice. Brain Abeta 1-x and x-42 levels were determined by ELISA. Leptomeningeal vascular and parenchymal amyloid burden(compact and diffuse) and neuritic dystrophy were assessed by Abeta and APP immunohistochemistry. Results: Treatment with 12.5 mg/kg/day for 13 weeks significantly reduced hippocampal amyloid burden and brain Abeta as measured by ELISA. Hippocampal neuritic burden, a measure of dystrophic neuronal response to compacted Abeta plaques and therefore an indirect measure of this plaque subtype, was not significantly reduced. However, a significant change in density of neuritic sites indicated an early effect on dystrophic neurites, consistent with a reduction in the number of small neuritic sites. At the lower dose administered once or twice daily for 13 weeks, a downward trend in hippocampal amyloid burden and neuritic burden was observed, and vascular and cortical amyloid burden, and brain Abeta were not significantly reduced. After 26 weeks of treatment at 12.5 mg/kg/day, the only dose tested at this timepoint, cortical and vascular amyloid burden and hippocampal neuritic burden were significantly reduced. There was a trend toward a decrease in brain Abeta as measured by ELISA. Conclusions: ELND006 effectively decreased the formation of, or prevented Abeta pathologies in the PDAPP mouse as assessed by histopathology and ELISA measures. These results support that a strategy for inhibiting gamma secretase may be efficacious in the treatment of AD and also of cerebral amyloid angiopathy, which is present in most AD patients.
P3-322
EFFECTS OF SINGLE AND MULTIPLE DOSE ORAL ADMINISTRATION OF ELND006, A NOVEL APPSELECTIVE GAMMA-SECRETASE INHIBITOR, ON AMYLOID-b CONCENTRATIONS IN THE BRAIN AND CSF OF CYNOMOLGUS MONKEYS
Elizabeth Brigham1, Kevin Quinn1, Ruth Motter1, Wherly Hoffman1, Erich Goldbach1, Dora Kholodenko1, Grace Kwong1, Chris Willits1, Gary Probst1, Jane Gunther1, Eric Adams2, John-Michael Sauer1, Gene Kinney1, Daniel Ness1, 1Elan Pharmaceuticals, South San Francisco, CA, USA; 2Northern Biomedical, Muskegon, MI, USA. Contact e-mail: beth. [email protected] Background: ELND006 is a potent, APP-selective gamma-secretase inhibitor currently being evaluated in Phase 1 human clinical trials. We present here the evaluation of ELND006 1) repeat-dose effects on beta-amyloid (Ab) levels in the brain, CSF and plasma of cynomolgus monkeys enrolled in nonclinical safety studies and 2) single-dose effects on Ab levels in the CSF and plasma of lumbar cannulated cynomolgus monkeys. Methods: For repeat-dose toxicology studies, cynomolgus monkeys were administered ELND006 once daily by oral gavage for 3 months. Brain, CSF and plasma samples were collected at termination, approximately 24 hours after the