- Email: [email protected]
Novel BACE1 inhibitor, E2609, lowers Aβ levels in the brain, cerebrospinal fluid and plasma in rats and guinea pigs
Poster Presentations: P1 P1-334
DEVELOPMENT AND APPLICATION OF A MATHEMATICAL MODEL OF MODULATION OF CEREBROSPINAL FLUID Ab40 AFTER TREATMENT WITH GAMMA- AND BETASECRETASE INHIBITORS
Huub Jan Kleijn, Lei Ma, Marissa Dockendorf, Rik de Greef, John Palcza, Michael Egan, Mark Forman, Julie Stone, Merck, Whitehouse Station, New Jersey, United States. Background: A mathematical model representation of key amyloid pathway physiology to describe A b 40 modulation in CSF was developed to: (1) quantify clinical drug potency of g-secretase (GS) and b -secretase (BACE1) inhibitors; (2) enable benchmarking across compounds; (3) facilitate dose selection for efficacy trials. Methods: Lumbar CSF A b 40 concentration data in healthy adults treated with placebo; GS inhibitors MK-0752 or semagacestat (from literature); or BACE inhibitor MK8931 were available. Model-predicted drug brain concentrations were used as driver for CSF A b 40 modulation. An Emax relationship described inhibition of A b 40 production and a distribution delay between brain and lumbar CSF A b 40 was incorporated. An additive baseline drift model informed by study-specific placebo data allowed for drift correction. Data were fit using non-linear mixed effects modeling and model performance was qualified. This model was combined with population PK models to predicted dose - response profiles for brain and CSF A b 40 inhibition. Trial performance predictions were made taking into account AD population demographics and knowledge on non-compliance. Results: An E max inhibition model combined with delay compartments best described the CSF A b 40 response upon inhibition of GS or BACE. Maximum inhibition (E max) estimates were 0.87, 0.86, 0.96 and for plasma concentration at 50% of maximum (EC 50) were 933 ng.mL -1, 6250 ng.mL -1, 10.2 ng.mL -1 for semagacestat, MK-0752, and MK-8931, respectively. Dose - response profiles demonstrated greater potency and achievable CSF A b 40 suppression with MK-8931 compared to other compounds at clinically feasible doses. CSF A b 40 reductions between 50-75%, and between 75-100% from baseline were predicted to be achieved in 90% of the patients at doses of 12 and 40 mg MK-8931, respectively. Conclusions: CSF A b 40 re-
Figure 1. Model-predicted inhibition of Ab brain production at steady state for daily dosing
P223
sponse following placebo and GS or BACE inhibition were characterized by a common model framework. Comparative analysis among compounds suggests that semagacestat produces only limited (<11%) inhibition of Ab production. MK-8931 showed superior potency in the expected therapeutic dose range resulting in almost full suppression of CSF A b 40. Simulations indicate that 12 and 40 mg MK-8931 inhibit Ab production by >50% and >75%, respectively, suggesting that clinical trials in AD with MK8931 may provide a more robust test of the amyloid hypothesis, compared to semagacestat.
P1-335
NOVEL BACE1 INHIBITOR, E2609, LOWERS Ab LEVELS IN THE BRAIN, CEREBROSPINAL FLUID AND PLASMA IN RATS AND GUINEA PIGS
Tatsuto Fukushima1, Yoshihide Osada1, Akira Ishibashi1, Fiona Lucas2, Eisai Co. Ltd., Tsukuba, Japan; 2Eisai Ltd. (at time of research), London, United Kingdom. 1
Background: Alzheimer’s disease (AD) is characterized by accumulation of Ab-containing plaques and tau-containing neurofibrillary tangles in the brain. BACE1 cleavage of amyloid precursor protein is the first step in Ab peptide production and, therefore, is a prime target to block the pathogenic amyloid cascade leading to AD. However, most BACE1 inhibitors described to date have shown limited in vivo CNS efficacy due to poor bioavailability and/or high susceptibility to Pgp transport. We have developed a potent small molecule BACE1 inhibitor, E2609 (cell-based assay IC 50 w7 nmol/L), with low susceptibility to Pgp transport in vitro. Methods: To assess in vivo CNS efficacy, E2609 was orally administered to rats (0.3-10 mg/kg). Abx40 and Abx-42 levels were measured in plasma, cerebrospinal fluid (CSF), and brain. Experiments were repeated in guinea pigs whose Ab sequence is identical to humans and from which Ab peptides beginning at position 1 can be measured using human ELISA kits. E2609 was orally administered to guinea pigs at doses 0.3-30 mg/kg. Results: In rats, E2609 showed a robust, dose-dependent decrease in levels of Abx-40 and Abx-42 in CSF and brain. At 10 mg/kg, the maximal effect reached w80% and w55% reductions in CSF and brain, respectively, 6 hours after administration. In plasma, no dose-response
was seen with maximal reduction of Abx-40 and Abx-42 around 50%. Guinea pigs orally administered E2609 showed similar results to rats, with robust dose-dependent decreases in Ab1-40 and Ab1-42 levels in CSF and brain (Figure). At 3 and 10 mg/kg, the maximal effect reached w85% reduction in CSF, and w74% reduction in brain, 4 hours after administration. In plasma, there was a dramatic reduction of Ab1-40 and Ab1-42 levels, peaking at w97% at 4 hours postdose, confirming the robust efficacy of E2609 and that the appropriate ELISA kit is essential for measuring BACE1-specific Ab peptides, especially in plasma. Conclusions: These results demonstrate that E2609 shows excellent in vivo CNS efficacy after a single oral
P224
Poster Presentations: P1
administration and highlight E2609 as an excellent candidate for further development.
P1-336
NOVEL BACE1 INHIBITOR, E2609, LOWERS Ab LEVELS IN THE CEREBROSPINAL FLUID AND PLASMA IN NONHUMAN PRIMATES
Fiona Lucas1, Tatsuto Fukushima2, Yoshitane Nozaki2, 1Eisai Ltd. (at time of research), London, United Kingdom; 2Eisai Co. Ltd., Tsukuba, Japan. Background: Alzheimer’s disease (AD) is characterized by accumulation of Ab-containing plaques and tau-containing neurofibrillary tangles in the brain. The production of pathological Ab peptides, Ab1-42 in particular, is thought to be an initiating event in AD. BACE1 cleavage of the amyloid precursor protein is the first step in the production of Ab and is therefore a prime target to block the pathogenic amyloid cascade leading to AD and potentially modify the disease progression. We have developed a potent small molecule, the orally bioavailable BACE1 inhibitor, E2609, (cell-based assay IC 50 w7 nmol/L) that has been shown to reduce Ab production in the plasma, brain, and cerebrospinal fluid (CSF) of rodents. Methods: The pharmacokinetic and pharmacodynamic relationship of E2609 was examined in cisterna magna ported cynomolgus monkeys. Plasma and CSF were sampled serially over 72 hours post single oral administration of E2609 so that the temporal dynamics of Ab in plasma and CSF could be evaluated in detail. Plasma pharmacokinetics of E2609 was linked to Ab levels
in plasma and CSF via pharmacokinetics/pharmacodynamics models which quantitatively estimated the in vivo pharmacodynamic potencies. Results: A single oral administration of E2609 significantly reduced plasma Ab1-40 and Ab1-42 levels equally, with an estimated plasma IC 50(unbound) of 1.3 nmol/L, concordant with the potency of the cell-based assay (Figure). E2609 reached a rapid equilibrium between plasma and CSF with near identical t max, and had a moderate to high CNS penetration. A single oral administration of E2609 led to an equal reduction of both CSF Ab1-40 and Ab1-42 levels. At effective doses, a peak reduction of up to w90% was observed in CSF that was sustained for 24 hours or more. The pharmacodynamic pa-
rameters for CSF Ab lowering (plasma IC 50,plasma IC 50(unbound)and k out) were estimated as 35.0 nmol/L, 9.7 nmol/L, and 0.148 hr -1 for Ab1-40, and 33.2 nmol/L, 9.2 nmol/L, and 0.148 hr -1 for Ab1-42, respectively. Conclusions: A single oral dose of E2609 potently inhibits Ab1-40 and Ab1-42 production in the plasma and CSF of non-human primates. These results highlight E2609 as an excellent candidate for further development as a potential therapy for AD.
P1-337
RESULTS OF A PHASE II STUDY OF PLASMA EXCHANGE WITH 5 PERCENT ALBUMIN (ALBUTEINÒ) IN ALZHEIMER’S DISEASE PATIENTS
Merce Boada-Rovira1, Laura Nunez Domenech2, Isabel Hernandez3, Javier Olazaran4, Fernando Anaya4, Joan Mu~noz5, Mar Buendia3, Lluis Tarraga3, Isabel Roca6, Gemma Cuberas6, Mireia Torres7, Joan Ramon Grifols5, Pilar Ortiz5, Angel Bittini4, Juan Guzman4, Isidro Ferrer8, Antonio Paez7, 1Fundacio ACE, Institut Catala de Neurociencies Aplicades, Barcelona, Spain; 2Instituto Grifols, Barcelona, Spain; 3Fundacio ACE, Institut Catala de Neurociencies Aplicades, Barcelona, Spain; 4Hospital General Universitario Gregorio Mara~non, Madrid, Spain; 5Banc de Sang i Teixits, Barcelona, Spain; 6Hospital General Universitari Vall d’Hebron, Barcelona, Spain; 7Instituto Grifols, Parets del Valles, Spain; 8Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Spain. Background: Neurocognitive changes were observed in a pilot study with Alzheimer’s disease (AD) patients submitted to plasma exchanges (PE) with Grifols 5% albumin (AlbuteinÒ) suggesting that further study is required to evaluate this treatment as a novel approach. Methods: Thirty-nine patients with mild-moderate AD receiving stable donepezil treatment were randomized to 2 groups (1:1): a control group and a treatment group. Both groups received a maximum of 18 PE with three different PE schedules with 5% AlbuteinÒ: 2 PE/week for 3 weeks, 1 PE/week for 6 weeks and 1 PE/2 weeks for 12 weeks. After the treatment period, there was a 6 months follow-up period for both groups. The control group followed the same program, except that the PE was a sham procedure. Plasma and CSF Ab40 and Ab42 levels, neuropsychological scores (MMSE, ADAS-Cog) and neuroimaging (MRI and SPECT) were performed along the study. The study was designed as a multicenter, randomized, blind, controlled, parallelgroup, phase II study. Results: In the treatment group treated patients, plasma Ab40 levels showed consistent variations in the form of a saw-tooth pattern throughout the three PE periods, replicating findings previously observed in the pilot study. After the PE periods, plasma Ab40 levels returned to baseline. Furthermore, treated patients scored better than control patients in cognitive evaluation (differences between groups at 9 months: 2.2 in MMSE and 4.5 in ADAS-Cog) but worsened at 12 months of follow-up (6 months after PE was over). Neuroimaging results have been reported in another abstract submitted to this congress by the same group. No plasma Ab40 variations were observed in the control group. Conclusions: These results confirm those of the pilot study suggesting that PE with Grifols 5% AlbuteinÒ consistently mobilizes plasma Ab levels. This type of mobilization was also observed for Grifols intravenous immunoglobulin (FlebogammaÒ DIF) suggesting that a combined treatment of plasmapheresis with 5% AlbuteinÒ and FlebogammaÒ DIF might be justified when a synergic effect is sought. However, the differences observed in cognitive scores need further confirmation in larger clinical trials.
P1-338
COMPARISON OF TOXIC BETA-AMYLOID OLIGOMER INHIBITORS FOR RESCUING MEMORY DEFICITS IN APP TRANSGENIC MICE
Andreas Muhs, Rime Madani, Heiko Kroth, Pascal Benderitter, Nampally Sreenivasachary, Cotinica Hame, Yvan Varisco,
DEVELOPMENT AND APPLICATION OF A MATHEMATICAL MODEL OF MODULATION OF CEREBROSPINAL FLUID Ab40 AFTER TREATMENT WITH GAMMA- AND BETASECRETASE INHIBITORS
Huub Jan Kleijn, Lei Ma, Marissa Dockendorf, Rik de Greef, John Palcza, Michael Egan, Mark Forman, Julie Stone, Merck, Whitehouse Station, New Jersey, United States. Background: A mathematical model representation of key amyloid pathway physiology to describe A b 40 modulation in CSF was developed to: (1) quantify clinical drug potency of g-secretase (GS) and b -secretase (BACE1) inhibitors; (2) enable benchmarking across compounds; (3) facilitate dose selection for efficacy trials. Methods: Lumbar CSF A b 40 concentration data in healthy adults treated with placebo; GS inhibitors MK-0752 or semagacestat (from literature); or BACE inhibitor MK8931 were available. Model-predicted drug brain concentrations were used as driver for CSF A b 40 modulation. An Emax relationship described inhibition of A b 40 production and a distribution delay between brain and lumbar CSF A b 40 was incorporated. An additive baseline drift model informed by study-specific placebo data allowed for drift correction. Data were fit using non-linear mixed effects modeling and model performance was qualified. This model was combined with population PK models to predicted dose - response profiles for brain and CSF A b 40 inhibition. Trial performance predictions were made taking into account AD population demographics and knowledge on non-compliance. Results: An E max inhibition model combined with delay compartments best described the CSF A b 40 response upon inhibition of GS or BACE. Maximum inhibition (E max) estimates were 0.87, 0.86, 0.96 and for plasma concentration at 50% of maximum (EC 50) were 933 ng.mL -1, 6250 ng.mL -1, 10.2 ng.mL -1 for semagacestat, MK-0752, and MK-8931, respectively. Dose - response profiles demonstrated greater potency and achievable CSF A b 40 suppression with MK-8931 compared to other compounds at clinically feasible doses. CSF A b 40 reductions between 50-75%, and between 75-100% from baseline were predicted to be achieved in 90% of the patients at doses of 12 and 40 mg MK-8931, respectively. Conclusions: CSF A b 40 re-
Figure 1. Model-predicted inhibition of Ab brain production at steady state for daily dosing
P223
sponse following placebo and GS or BACE inhibition were characterized by a common model framework. Comparative analysis among compounds suggests that semagacestat produces only limited (<11%) inhibition of Ab production. MK-8931 showed superior potency in the expected therapeutic dose range resulting in almost full suppression of CSF A b 40. Simulations indicate that 12 and 40 mg MK-8931 inhibit Ab production by >50% and >75%, respectively, suggesting that clinical trials in AD with MK8931 may provide a more robust test of the amyloid hypothesis, compared to semagacestat.
P1-335
NOVEL BACE1 INHIBITOR, E2609, LOWERS Ab LEVELS IN THE BRAIN, CEREBROSPINAL FLUID AND PLASMA IN RATS AND GUINEA PIGS
Tatsuto Fukushima1, Yoshihide Osada1, Akira Ishibashi1, Fiona Lucas2, Eisai Co. Ltd., Tsukuba, Japan; 2Eisai Ltd. (at time of research), London, United Kingdom. 1
Background: Alzheimer’s disease (AD) is characterized by accumulation of Ab-containing plaques and tau-containing neurofibrillary tangles in the brain. BACE1 cleavage of amyloid precursor protein is the first step in Ab peptide production and, therefore, is a prime target to block the pathogenic amyloid cascade leading to AD. However, most BACE1 inhibitors described to date have shown limited in vivo CNS efficacy due to poor bioavailability and/or high susceptibility to Pgp transport. We have developed a potent small molecule BACE1 inhibitor, E2609 (cell-based assay IC 50 w7 nmol/L), with low susceptibility to Pgp transport in vitro. Methods: To assess in vivo CNS efficacy, E2609 was orally administered to rats (0.3-10 mg/kg). Abx40 and Abx-42 levels were measured in plasma, cerebrospinal fluid (CSF), and brain. Experiments were repeated in guinea pigs whose Ab sequence is identical to humans and from which Ab peptides beginning at position 1 can be measured using human ELISA kits. E2609 was orally administered to guinea pigs at doses 0.3-30 mg/kg. Results: In rats, E2609 showed a robust, dose-dependent decrease in levels of Abx-40 and Abx-42 in CSF and brain. At 10 mg/kg, the maximal effect reached w80% and w55% reductions in CSF and brain, respectively, 6 hours after administration. In plasma, no dose-response
was seen with maximal reduction of Abx-40 and Abx-42 around 50%. Guinea pigs orally administered E2609 showed similar results to rats, with robust dose-dependent decreases in Ab1-40 and Ab1-42 levels in CSF and brain (Figure). At 3 and 10 mg/kg, the maximal effect reached w85% reduction in CSF, and w74% reduction in brain, 4 hours after administration. In plasma, there was a dramatic reduction of Ab1-40 and Ab1-42 levels, peaking at w97% at 4 hours postdose, confirming the robust efficacy of E2609 and that the appropriate ELISA kit is essential for measuring BACE1-specific Ab peptides, especially in plasma. Conclusions: These results demonstrate that E2609 shows excellent in vivo CNS efficacy after a single oral
P224
Poster Presentations: P1
administration and highlight E2609 as an excellent candidate for further development.
P1-336
NOVEL BACE1 INHIBITOR, E2609, LOWERS Ab LEVELS IN THE CEREBROSPINAL FLUID AND PLASMA IN NONHUMAN PRIMATES
Fiona Lucas1, Tatsuto Fukushima2, Yoshitane Nozaki2, 1Eisai Ltd. (at time of research), London, United Kingdom; 2Eisai Co. Ltd., Tsukuba, Japan. Background: Alzheimer’s disease (AD) is characterized by accumulation of Ab-containing plaques and tau-containing neurofibrillary tangles in the brain. The production of pathological Ab peptides, Ab1-42 in particular, is thought to be an initiating event in AD. BACE1 cleavage of the amyloid precursor protein is the first step in the production of Ab and is therefore a prime target to block the pathogenic amyloid cascade leading to AD and potentially modify the disease progression. We have developed a potent small molecule, the orally bioavailable BACE1 inhibitor, E2609, (cell-based assay IC 50 w7 nmol/L) that has been shown to reduce Ab production in the plasma, brain, and cerebrospinal fluid (CSF) of rodents. Methods: The pharmacokinetic and pharmacodynamic relationship of E2609 was examined in cisterna magna ported cynomolgus monkeys. Plasma and CSF were sampled serially over 72 hours post single oral administration of E2609 so that the temporal dynamics of Ab in plasma and CSF could be evaluated in detail. Plasma pharmacokinetics of E2609 was linked to Ab levels
in plasma and CSF via pharmacokinetics/pharmacodynamics models which quantitatively estimated the in vivo pharmacodynamic potencies. Results: A single oral administration of E2609 significantly reduced plasma Ab1-40 and Ab1-42 levels equally, with an estimated plasma IC 50(unbound) of 1.3 nmol/L, concordant with the potency of the cell-based assay (Figure). E2609 reached a rapid equilibrium between plasma and CSF with near identical t max, and had a moderate to high CNS penetration. A single oral administration of E2609 led to an equal reduction of both CSF Ab1-40 and Ab1-42 levels. At effective doses, a peak reduction of up to w90% was observed in CSF that was sustained for 24 hours or more. The pharmacodynamic pa-
rameters for CSF Ab lowering (plasma IC 50,plasma IC 50(unbound)and k out) were estimated as 35.0 nmol/L, 9.7 nmol/L, and 0.148 hr -1 for Ab1-40, and 33.2 nmol/L, 9.2 nmol/L, and 0.148 hr -1 for Ab1-42, respectively. Conclusions: A single oral dose of E2609 potently inhibits Ab1-40 and Ab1-42 production in the plasma and CSF of non-human primates. These results highlight E2609 as an excellent candidate for further development as a potential therapy for AD.
P1-337
RESULTS OF A PHASE II STUDY OF PLASMA EXCHANGE WITH 5 PERCENT ALBUMIN (ALBUTEINÒ) IN ALZHEIMER’S DISEASE PATIENTS
Merce Boada-Rovira1, Laura Nunez Domenech2, Isabel Hernandez3, Javier Olazaran4, Fernando Anaya4, Joan Mu~noz5, Mar Buendia3, Lluis Tarraga3, Isabel Roca6, Gemma Cuberas6, Mireia Torres7, Joan Ramon Grifols5, Pilar Ortiz5, Angel Bittini4, Juan Guzman4, Isidro Ferrer8, Antonio Paez7, 1Fundacio ACE, Institut Catala de Neurociencies Aplicades, Barcelona, Spain; 2Instituto Grifols, Barcelona, Spain; 3Fundacio ACE, Institut Catala de Neurociencies Aplicades, Barcelona, Spain; 4Hospital General Universitario Gregorio Mara~non, Madrid, Spain; 5Banc de Sang i Teixits, Barcelona, Spain; 6Hospital General Universitari Vall d’Hebron, Barcelona, Spain; 7Instituto Grifols, Parets del Valles, Spain; 8Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Spain. Background: Neurocognitive changes were observed in a pilot study with Alzheimer’s disease (AD) patients submitted to plasma exchanges (PE) with Grifols 5% albumin (AlbuteinÒ) suggesting that further study is required to evaluate this treatment as a novel approach. Methods: Thirty-nine patients with mild-moderate AD receiving stable donepezil treatment were randomized to 2 groups (1:1): a control group and a treatment group. Both groups received a maximum of 18 PE with three different PE schedules with 5% AlbuteinÒ: 2 PE/week for 3 weeks, 1 PE/week for 6 weeks and 1 PE/2 weeks for 12 weeks. After the treatment period, there was a 6 months follow-up period for both groups. The control group followed the same program, except that the PE was a sham procedure. Plasma and CSF Ab40 and Ab42 levels, neuropsychological scores (MMSE, ADAS-Cog) and neuroimaging (MRI and SPECT) were performed along the study. The study was designed as a multicenter, randomized, blind, controlled, parallelgroup, phase II study. Results: In the treatment group treated patients, plasma Ab40 levels showed consistent variations in the form of a saw-tooth pattern throughout the three PE periods, replicating findings previously observed in the pilot study. After the PE periods, plasma Ab40 levels returned to baseline. Furthermore, treated patients scored better than control patients in cognitive evaluation (differences between groups at 9 months: 2.2 in MMSE and 4.5 in ADAS-Cog) but worsened at 12 months of follow-up (6 months after PE was over). Neuroimaging results have been reported in another abstract submitted to this congress by the same group. No plasma Ab40 variations were observed in the control group. Conclusions: These results confirm those of the pilot study suggesting that PE with Grifols 5% AlbuteinÒ consistently mobilizes plasma Ab levels. This type of mobilization was also observed for Grifols intravenous immunoglobulin (FlebogammaÒ DIF) suggesting that a combined treatment of plasmapheresis with 5% AlbuteinÒ and FlebogammaÒ DIF might be justified when a synergic effect is sought. However, the differences observed in cognitive scores need further confirmation in larger clinical trials.
P1-338
COMPARISON OF TOXIC BETA-AMYLOID OLIGOMER INHIBITORS FOR RESCUING MEMORY DEFICITS IN APP TRANSGENIC MICE
Andreas Muhs, Rime Madani, Heiko Kroth, Pascal Benderitter, Nampally Sreenivasachary, Cotinica Hame, Yvan Varisco,