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Browsing by Author "Keezer, Kelly J."
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Item Pharmacokinetic, pharmacodynamic, and transcriptomic analysis of chronic levetiracetam treatment in 5XFAD mice: A MODEL-AD preclinical testing core study(Wiley, 2022-08-23) Onos, Kristen D.; Quinney, Sara K.; Jones, David R.; Masters, Andrea R.; Pandey, Ravi; Keezer, Kelly J.; Biesdorf, Carla; Metzger, Ingrid F.; Meyers, Jill A.; Peters, Johnathon; Persohn, Scott C.; McCarthy, Brian P.; Bedwell, Amanda A.; Figueiredo, Lucas L.; Cope, Zackary A.; Sasner, Michael; Howell, Gareth R.; Williams, Harriet M.; Oblak, Adrian L.; Lamb, Bruce T.; Carter, Gregory W.; Sukoff Rizzo, Stacey J.; Territo, Paul R.; Obstetrics and Gynecology, School of MedicineIntroduction: Hyperexcitability and epileptiform activity are commonplace in Alzheimer's disease (AD) patients and associated with impaired cognitive function. The anti-seizure drug levetiracetam (LEV) is currently being evaluated in clinical trials for ability to reduce epileptiform activity and improve cognitive function in AD. The purpose of our studies was to establish a pharmacokinetic/pharmacodynamic (PK/PD) relationship with LEV in an amyloidogenic mouse model of AD to enable predictive preclinical to clinical translation, using the rigorous preclinical testing pipeline of the Model Organism Development and Evaluation for Late-Onset Alzheimer's Disease Preclinical Testing Core. Methods: A multi-tier approach was applied that included quality assurance and quality control of the active pharmaceutical ingredient, PK/PD modeling, positron emission tomography/magnetic resonance imaging (PET/MRI), functional outcomes, and transcriptomics. 5XFAD mice were treated chronically with LEV for 3 months at doses in line with those allometrically scaled to the clinical dose range. Results: Pharmacokinetics of LEV demonstrated sex differences in Cmax, AUC0-∞, and CL/F, and a dose dependence in AUC0-∞. After chronic dosing at 10, 30, 56 mg/kg, PET/MRI tracer 18F-AV45, and 18F-fluorodeoxyglucose (18F-FDG) showed specific regional differences with treatment. LEV did not significantly improve cognitive outcomes. Transcriptomics performed by nanoString demonstrated drug- and dose-related changes in gene expression relevant to human brain regions and pathways congruent with changes in 18F-FDG uptake. Discussion: This study represents the first report of PK/PD assessment of LEV in 5XFAD mice. Overall, these results highlighted non-linear kinetics based on dose and sex. Plasma concentrations of the 10 mg/kg dose in 5XFAD overlapped with human plasma concentrations used for studies of mild cognitive impairment, while the 30 and 56 mg/kg doses were reflective of doses used to treat seizure activity. Post-treatment gene expression analysis demonstrated LEV dose-related changes in immune function and neuronal-signaling pathways relevant to human AD, and aligned with regional 18F-FDG uptake. Overall, this study highlights the importance of PK/PD relationships in preclinical studies to inform clinical study design. Highlights: Significant sex differences in pharmacokinetics of levetiracetam were observed in 5XFAD mice. Plasma concentrations of 10 mg/kg levetiracetam dose in 5XFAD overlapped with human plasma concentration used in the clinic. Drug- and dose-related differences in gene expression relevant to human brain regions and pathways were also similar to brain region-specific changes in 18F-fluorodeoxyglucose uptake.Item Prophylactic evaluation of verubecestat on disease- and symptom-modifying effects in 5XFAD mice(Alzheimer’s Association, 2022-07-14) Oblak, Adrian L.; Cope, Zackary A.; Quinney, Sara K.; Pandey, Ravi S.; Biesdorf, Carla; Masters, Andi R.; Onos, Kristen D.; Haynes, Leslie; Keezer, Kelly J.; Meyer, Jill A.; Peters, Jonathan S.; Persohn, Scott A.; Bedwell, Amanda A.; Eldridge, Kierra; Speedy, Rachael; Little, Gabriela; Williams, Sean-Paul; Noarbe, Brenda; Obenaus, Andre; Sasner, Michael; Howell, Gareth R.; Carter, Gregory W.; Williams, Harriet; Lamb, Bruce T.; Territo, Paul R.; Sukoff Rizzo, Stacey J.; Radiology and Imaging Sciences, School of MedicineIntroduction: Alzheimer's disease (AD) is the most common form of dementia. Beta-secretase (BACE) inhibitors have been proposed as potential therapeutic interventions; however, initiating treatment once disease has significantly progressed has failed to effectively stop or treat disease. Whether BACE inhibition may have efficacy when administered prophylactically in the early stages of AD has been under-investigated. The present studies aimed to evaluate prophylactic treatment of the BACE inhibitor verubecestat in an AD mouse model using the National Institute on Aging (NIA) resources of the Model Organism Development for Late-Onset Alzheimer's Disease (MODEL-AD) Preclinical Testing Core (PTC) Drug Screening Pipeline. Methods: 5XFAD mice were administered verubecestat ad libitum in chow from 3 to 6 months of age, prior to the onset of significant disease pathology. Following treatment (6 months of age), in vivo imaging was conducted with 18F-florbetapir (AV-45/Amyvid) (18F-AV45) and 18-FDG (fluorodeoxyglucose)-PET (positron emission tomography)/MRI (magnetic resonance imaging), brain and plasma amyloid beta (Aβ) were measured, and the clinical and behavioral characteristics of the mice were assessed and correlated with the pharmacokinetic data. Results: Prophylactic verubecestat treatment resulted in dose- and region-dependent attenuations of 18F-AV45 uptake in male and female 5XFAD mice. Plasma Aβ40 and Aβ42 were also dose-dependently attenuated with treatment. Across the dose range evaluated, side effects including coat color changes and motor alterations were reported, in the absence of cognitive improvement or changes in 18F-FDG uptake. Discussion: Prophylactic treatment with verubecestat resulted in attenuated amyloid plaque deposition when treatment was initiated prior to significant pathology in 5XFAD mice. At the same dose range effective at attenuating Aβ levels, verubecestat produced side effects in the absence of improvements in cognitive function. Taken together these data demonstrate the rigorous translational approaches of the MODEL-AD PTC for interrogating potential therapeutics and provide insight into the limitations of verubecestat as a prophylactic intervention for early-stage AD.