Early immune factors associated with the development of post-acute sequelae of SARS-CoV-2 infection in hospitalized and non-hospitalized individuals.

Background: Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can lead to post-acute sequelae of SARS-CoV-2 (PASC) that can persist for weeks to years following initial viral infection. Clinical manifestations of PASC are heterogeneous and often involve multiple organs. While many hypotheses have been made on the mechanisms of PASC and its associated symptoms, the acute biological drivers of PASC are still unknown. Methods: We enrolled 494 patients with COVID-19 at their initial presentation to a hospital or clinic and followed them longitudinally to determine their development of PASC. From 341 patients, we conducted multi-omic profiling on peripheral blood samples collected shortly after study enrollment to investigate early immune signatures associated with the development of PASC. Results: During the first week of COVID-19, we observed a large number of differences in the immune profile of individuals who were hospitalized for COVID-19 compared to those individuals with COVID-19 who were not hospitalized. Differences between individuals who did or did not later develop PASC were, in comparison, more limited, but included significant differences in autoantibodies and in epigenetic and transcriptional signatures in double-negative 1 B cells, in particular. Conclusions: We found that early immune indicators of incident PASC were nuanced, with significant molecular signals manifesting predominantly in double-negative B cells, compared with the robust differences associated with hospitalization during acute COVID-19. The emerging acute differences in B cell phenotypes, especially in double-negative 1 B cells, in PASC patients highlight a potentially important role of these cells in the development of PASC.

Multi-omic profiling reveals early immunological indicators for identifying COVID-19 Progressors.

We sought to better understand the immune response during the immediate post-diagnosis phase of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by identifying molecular associations with longitudinal disease outcomes. Multi-omic analyses identified differences in immune cell composition, cytokine levels, and cell subset-specific transcriptomic and epigenomic signatures between individuals on a more serious disease trajectory (Progressors) as compared to those on a milder course (Non-progressors). Higher levels of multiple cytokines were observed in Progressors, with IL-6 showing the largest difference. Blood monocyte cell subsets were also skewed, showing a comparative decrease in non-classical CD14-CD16+ and intermediate CD14+CD16+ monocytes. In lymphocytes, the CD8+ T effector memory cells displayed a gene expression signature consistent with stronger T cell activation in Progressors. These early stage observations could serve as the basis for the development of prognostic biomarkers of disease risk and interventional strategies to improve the management of severe COVID-19. BACKGROUND: Much of the literature on immune response post-SARS-CoV-2 infection has been in the acute and post-acute phases of infection. TRANSLATIONAL SIGNIFICANCE: We found differences at early time points of infection in approximately 160 participants. We compared multi-omic signatures in immune cells between individuals progressing to needing more significant medical intervention and non-progressors. We observed widespread evidence of a state of increased inflammation associated with progression, supported by a range of epigenomic, transcriptomic, and proteomic signatures. The signatures we identified support other findings at later time points and serve as the basis for prognostic biomarker development or to inform interventional strategies.

Multi-omic Profiling Reveals Early Immunological Indicators for Identifying COVID-19 Progressors.

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a rapid response by the scientific community to further understand and combat its associated pathologic etiology. A focal point has been on the immune responses mounted during the acute and post-acute phases of infection, but the immediate post-diagnosis phase remains relatively understudied. We sought to better understand the immediate post-diagnosis phase by collecting blood from study participants soon after a positive test and identifying molecular associations with longitudinal disease outcomes. Multi-omic analyses identified differences in immune cell composition, cytokine levels, and cell subset-specific transcriptomic and epigenomic signatures between individuals on a more serious disease trajectory (Progressors) as compared to those on a milder course (Non-progressors). Higher levels of multiple cytokines were observed in Progressors, with IL-6 showing the largest difference. Blood monocyte cell subsets were also skewed, showing a comparative decrease in non-classical CD14-CD16+ and intermediate CD14+CD16+ monocytes. Additionally, in the lymphocyte compartment, CD8+ T effector memory cells displayed a gene expression signature consistent with stronger T cell activation in Progressors. Importantly, the identification of these cellular and molecular immune changes occurred at the early stages of COVID-19 disease. These observations could serve as the basis for the development of prognostic biomarkers of disease risk and interventional strategies to improve the management of severe COVID-19.

Psychometric testing of the Fall Risks for Older People in the Community screening tool (FROP-Com screen) for community-dwelling people with stroke.

OBJECTIVE: The Falls Risk for Older People in the Community assessment (FROP-Com) was originally developed using 13 risk factors to identify the fall risks of community-dwelling older people. To suit the practical use in busy clinical settings, a brief version adopting 3 most fall predictive risk factors from the original FROP-Com, including the number of falls in the past 12 months, assistance required to perform domestic activities of daily living and observation of balance, was developed for screening purpose (FROP-Com screen). The objectives of this study were to investigate the inter-rater and test-retest reliability, concurrent and convergent validity, and minimum detectable change of the FROP-Com screen in community-dwelling people with stroke. PARTICIPANTS: Community-dwelling people with stroke (n = 48) were recruited from a local self-help group, and community-dwelling older people (n = 40) were recruited as control subjects. RESULTS: The FROP-Com screen exhibited moderate inter-rater (Intraclass correlation coefficient [ICC]2,1 = 0.79, 95% confidence interval [CI]: 0.65-0.87) and test-retest reliability (ICC3,1 = 0.70, 95% CI: 0.46-0.83) and weak associations with two balance measures, the Berg Balance Scale (BBS) (rho = -0.38, p = 0.008) and the Timed "Up & Go" (TUG) test (rho = 0.35, p = 0.016). The screen also exhibited a moderate association with the Chinese version of the Activities-specific Balance Confidence Scale (ABC-C) (ABC-C; rho = -0.65, p<0.001), a measure of subjective balance confidence. CONCLUSIONS: The FROP-Com screen is a reliable clinical tool with convergent validity paralleled with subjective balance confidence measure that can be used in fall risk screening of community-dwelling people with stroke. However, one individual item, the observation of balance, will require additional refinement to improve the potential measurement error.

Present Algorithms and Future Treatments for Alzheimer's Disease.

An estimated 47 million people live with Alzheimer's disease (AD) and other forms of dementia worldwide. Although no disease-modifying treatments are currently available for AD, earlier diagnosis and proper management of the disease could have considerable impact on patient and caregiver quality of life and functioning. Drugs currently approved for AD treat the cognitive, behavioral, and functional symptoms of the disease and consist of three cholinesterase inhibitors (ChEIs) and the N-methyl-D-aspartate receptor antagonist memantine. Treatment of patients with mild to moderate AD is generally initiated with a ChEI. Patients who show progression of symptoms while on ChEI monotherapy may be switched to another ChEI and/or memantine can be added to the treatment regimen. In recent years, putative disease-modifying therapies have emerged that aim to slow the progression of AD instead of only addressing its symptoms. However, many therapies have failed in clinical trials in patients with established AD, suggesting that, once developed, disease-modifying agents may need to be deployed earlier in the course of illness. The goal of this narrative literature review is to discuss present treatment algorithms and potential future therapies in AD.

Treatment Combinations for Alzheimer's Disease: Current and Future Pharmacotherapy Options.

Although Alzheimer's disease (AD) is the world's leading cause of dementia and the population of patients with AD continues to grow, no new therapies have been approved in more than a decade. Many clinical trials of single-agent therapies have failed to affect disease progression or symptoms compared with placebo. The complex pathophysiology of AD may necessitate combination treatments rather than monotherapy. The goal of this narrative literature review is to describe types of combination therapy, review the current clinical evidence for combination therapy regimens (both symptomatic and disease-modifying) in the treatment of AD, describe innovative clinical trial study designs that may be effective in testing combination therapy, and discuss the regulatory and drug development landscape for combination therapy. Successful combination therapies in other complex disorders, such as human immunodeficiency virus, may provide useful examples of a potential path forward for AD treatment.

Current state of Alzheimer's fluid biomarkers.

Alzheimer's disease (AD) is a progressive neurodegenerative disease with a complex and heterogeneous pathophysiology. The number of people living with AD is predicted to increase; however, there are no disease-modifying therapies currently available and none have been successful in late-stage clinical trials. Fluid biomarkers measured in cerebrospinal fluid (CSF) or blood hold promise for enabling more effective drug development and establishing a more personalized medicine approach for AD diagnosis and treatment. Biomarkers used in drug development programmes should be qualified for a specific context of use (COU). These COUs include, but are not limited to, subject/patient selection, assessment of disease state and/or prognosis, assessment of mechanism of action, dose optimization, drug response monitoring, efficacy maximization, and toxicity/adverse reactions identification and minimization. The core AD CSF biomarkers Aß42, t-tau, and p-tau are recognized by research guidelines for their diagnostic utility and are being considered for qualification for subject selection in clinical trials. However, there is a need to better understand their potential for other COUs, as well as identify additional fluid biomarkers reflecting other aspects of AD pathophysiology. Several novel fluid biomarkers have been proposed, but their role in AD pathology and their use as AD biomarkers have yet to be validated. In this review, we summarize some of the pathological mechanisms implicated in the sporadic AD and highlight the data for several established and novel fluid biomarkers (including BACE1, TREM2, YKL-40, IP-10, neurogranin, SNAP-25, synaptotagmin, α-synuclein, TDP-43, ferritin, VILIP-1, and NF-L) associated with each mechanism. We discuss the potential COUs for each biomarker.

The National Institute on Aging and the Alzheimer's Association Research Framework for Alzheimer's disease: Perspectives from the Research Roundtable.

The Alzheimer's Association's Research Roundtable met in November 2017 to explore the new National Institute on Aging and the Alzheimer's Association Research Framework for Alzheimer's disease. The meeting allowed experts in the field from academia, industry, and government to provide perspectives on the new National Institute on Aging and the Alzheimer's Association Research Framework. This review will summarize the "A, T, N System" (Amyloid, Tau, and Neurodegeneration) using biomarkers and how this may be applied to clinical research and drug development. In addition, challenges and barriers to the potential adoption of this new framework will be discussed. Finally, future directions for research will be proposed.

A Cas9-based toolkit to program gene expression in Saccharomyces cerevisiae.

Despite the extensive use of Saccharomyces cerevisiae as a platform for synthetic biology, strain engineering remains slow and laborious. Here, we employ CRISPR/Cas9 technology to build a cloning-free toolkit that addresses commonly encountered obstacles in metabolic engineering, including chromosomal integration locus and promoter selection, as well as protein localization and solubility. The toolkit includes 23 Cas9-sgRNA plasmids, 37 promoters of various strengths and temporal expression profiles, and 10 protein-localization, degradation and solubility tags. We facilitated the use of these parts via a web-based tool, that automates the generation of DNA fragments for integration. Our system builds upon existing gene editing methods in the thoroughness with which the parts are standardized and characterized, the types and number of parts available and the ease with which our methodology can be used to perform genetic edits in yeast. We demonstrated the applicability of this toolkit by optimizing the expression of a challenging but industrially important enzyme, taxadiene synthase (TXS). This approach enabled us to diagnose an issue with TXS solubility, the resolution of which yielded a 25-fold improvement in taxadiene production.

Pharmacologically targeted NMDA receptor antagonism by NitroMemantine for cerebrovascular disease.

Stroke and vascular dementia are leading causes of morbidity and mortality. Neuroprotective therapies have been proposed but none have proven clinically tolerated and effective. While overstimulation of N-methyl-d-aspartate-type glutamate receptors (NMDARs) is thought to contribute to cerebrovascular insults, the importance of NMDARs in physiological function has made this target, at least in the view of many in 'Big Pharma,' 'undruggable' for this indication. Here, we describe novel NitroMemantine drugs, comprising an adamantane moiety that binds in the NMDAR-associated ion channel that is used to target a nitro group to redox-mediated regulatory sites on the receptor. The NitroMemantines are both well tolerated and effective against cerebral infarction in rodent models via a dual allosteric mechanism of open-channel block and NO/redox modulation of the receptor. Targeted S-nitrosylation of NMDARs by NitroMemantine is potentiated by hypoxia and thereby directed at ischemic neurons. Allosteric approaches to tune NMDAR activity may hold therapeutic potential for cerebrovascular disorders.

An integrated multi-study analysis of intra-subject variability in cerebrospinal fluid amyloid-ß concentrations collected by lumbar puncture and indwelling lumbar catheter.

INTRODUCTION: Amyloid-ß (Aß) has been investigated as a diagnostic biomarker and therapeutic drug target. Recent studies found that cerebrospinal fluid (CSF) Aß fluctuates over time, including as a diurnal pattern, and increases in absolute concentration with serial collection. It is currently unknown what effect differences in CSF collection methodology have on Aß variability. In this study, we sought to determine the effect of different collection methodologies on the stability of CSF Aß concentrations over time. METHODS: Grouped analysis of CSF Aß levels from multiple industry and academic groups collected by either lumbar puncture (n=83) or indwelling lumbar catheter (n=178). Participants were either placebo or untreated subjects from clinical drug trials or observational studies. Participants had CSF collected by lumbar puncture or lumbar catheter for quantitation of Aß concentration by enzyme linked immunosorbent assay. Data from all sponsors was converted to percent of the mean for Aß40 and Aß42 for comparison. Repeated measures analysis of variance was performed to assess for factors affecting the linear rise of Aß concentrations over time. RESULTS: Analysis of studies collecting CSF via lumbar catheter revealed tremendous inter-subject variability of Aß40 and Aß42 as well as an Aß diurnal pattern in all of the sponsors' studies. In contrast, Aß concentrations from CSF samples collected at two time points by lumbar puncture showed no significant differences. Repeated measures analysis of variance found that only time and draw frequency were significantly associated with the slope of linear rise in Aß40 and Aß42 concentrations during the first 6 hours of collection. CONCLUSIONS: Based on our findings, we recommend minimizing the frequency of CSF draws in studies measuring Aß levels and keeping the frequency standardized between experimental groups. The Aß diurnal pattern was noted in all sponsors' studies and was not an artifact of study design. Averaging Aß concentrations at each time point is recommended to minimize the effect of individual variability. Indwelling lumbar catheters are an invaluable research tool for following changes in CSF Aß over 24-48 hours, but factors affecting Aß concentration such as linear rise and diurnal variation need to be accounted for in planning study designs.

Aß induces astrocytic glutamate release, extrasynaptic NMDA receptor activation, and synaptic loss.

Synaptic loss is the cardinal feature linking neuropathology to cognitive decline in Alzheimer's disease (AD). However, the mechanism of synaptic damage remains incompletely understood. Here, using FRET-based glutamate sensor imaging, we show that amyloid-ß peptide (Aß) engages α7 nicotinic acetylcholine receptors to induce release of astrocytic glutamate, which in turn activates extrasynaptic NMDA receptors (eNMDARs) on neurons. In hippocampal autapses, this eNMDAR activity is followed by reduction in evoked and miniature excitatory postsynaptic currents (mEPSCs). Decreased mEPSC frequency may reflect early synaptic injury because of concurrent eNMDAR-mediated NO production, tau phosphorylation, and caspase-3 activation, each of which is implicated in spine loss. In hippocampal slices, oligomeric Aß induces eNMDAR-mediated synaptic depression. In AD-transgenic mice compared with wild type, whole-cell recordings revealed excessive tonic eNMDAR activity accompanied by eNMDAR-sensitive loss of mEPSCs. Importantly, the improved NMDAR antagonist NitroMemantine, which selectively inhibits extrasynaptic over physiological synaptic NMDAR activity, protects synapses from Aß-induced damage both in vitro and in vivo.

Pharmacodynamics of selective inhibition of γ-secretase by avagacestat.

A hallmark of Alzheimer's disease (AD) pathology is the accumulation of brain amyloid ß-peptide (Aß), generated by γ-secretase-mediated cleavage of the amyloid precursor protein (APP). Therefore, γ-secretase inhibitors (GSIs) may lower brain Aß and offer a potential new approach to treat AD. As γ-secretase also cleaves Notch proteins, GSIs can have undesirable effects due to interference with Notch signaling. Avagacestat (BMS-708163) is a GSI developed for selective inhibition of APP over Notch cleavage. Avagacestat inhibition of APP and Notch cleavage was evaluated in cell culture by measuring levels of Aß and human Notch proteins. In rats, dogs, and humans, selectivity was evaluated by measuring plasma blood concentrations in relation to effects on cerebrospinal fluid (CSF) Aß levels and Notch-related toxicities. Measurements of Notch-related toxicity included goblet cell metaplasia in the gut, marginal-zone depletion in the spleen, reductions in B cells, and changes in expression of the Notch-regulated hairy and enhancer of split homolog-1 from blood cells. In rats and dogs, acute administration of avagacestat robustly reduced CSF Aß40 and Aß42 levels similarly. Chronic administration in rats and dogs, and 28-day, single- and multiple-ascending-dose administration in healthy human subjects caused similar exposure-dependent reductions in CSF Aß40. Consistent with the 137-fold selectivity measured in cell culture, we identified doses of avagacestat that reduce CSF Aß levels without causing Notch-related toxicities. Our results demonstrate the selectivity of avagacestat for APP over Notch cleavage, supporting further evaluation of avagacestat for AD therapy.

A contrast in safety, pharmacokinetics and pharmacodynamics across age groups after a single 50 mg oral dose of the γ-secretase inhibitor avagacestat.

AIM: To evaluate the single dose pharmacokinetics, pharmacodynamics, and preliminary tolerability of the γ-secretase inhibitor BMS-708163 (avagacestat) in young and elderly men and women. METHODS: All subjects received double-blinded administration of a single 50 mg dose of avagacestat in capsule form or matching placebo. Main evaluations included pharmacokinetics, safety, plasma amyloid-ß (Aß)(1-40) concentratios and exploration of Notch biomarkers. RESULTS: Avagacestat 50 mg capsule was well tolerated and rapidly absorbed among young and elderly subjects, with a median t(max) between 1 and 2 h post dose and an average half-life between 41 and 71 h. In general, subjects aged 75 years or more had higher AUC(0,∞) values than those aged less than 75 years. An exploratory analysis of Aß(1-40) serum concentrations showed a pattern of decreasing concentrations over the first 4-6 h followed by a rise above baseline that was maintained until the end of the assessment period. Adverse events were generally mild, occurring more frequently in elderly subjects, with no observed difference between subjects receiving avagacestat and placebo. No dose limiting gastrointestinal effects of avagacestat were observed and exploratory biomarkers of Notch inhibition did not change significantly. CONCLUSIONS: The favourable safety profile and pharmacokinetic effects of avagacestat in this study support its continued development, especially in the target population of elderly subjects with mild cognitive impairment or Alzheimer's disease.

Frontotemporal degeneration, the next therapeutic frontier: molecules and animal models for frontotemporal degeneration drug development.

Frontotemporal degeneration (FTD) is a common cause of dementia for which there are currently no approved therapies. Over the past decade, there has been an explosion of knowledge about the biology and clinical features of FTD that has identified a number of promising therapeutic targets as well as animal models in which to develop drugs. The close association of some forms of FTD with neuropathological accumulation of tau protein or increased neuroinflammation due to progranulin protein deficiency suggests that a drug's success in treating FTD may predict efficacy in more common diseases such as Alzheimer's disease. A variety of regulatory incentives, clinical features of FTD such as rapid disease progression, and relatively pure molecular pathology suggest that there are advantages to developing drugs for FTD as compared with other more common neurodegenerative diseases such as Alzheimer's disease. In March 2011, the Frontotemporal Degeneration Treatment Study Group sponsored a conference entitled "FTD, the Next Therapeutic Frontier," which focused on preclinical aspects of FTD drug development. The goal of the meeting was to promote collaborations between academic researchers and biotechnology and pharmaceutical researchers to accelerate the development of new treatments for FTD. Here we report the key findings from the conference, including the rationale for FTD drug development; epidemiological, genetic, and neuropathological features of FTD; FTD animal models and how best to use them; and examples of successful drug development collaborations in other neurodegenerative diseases.

The advantages of frontotemporal degeneration drug development (part 2 of frontotemporal degeneration: the next therapeutic frontier).

Frontotemporal degeneration (FTD) encompasses a spectrum of related neurodegenerative disorders with behavioral, language, and motor phenotypes for which there are currently no effective therapies. This is the second of two articles that summarize the presentations and discussions that occurred at two symposia in 2011 sponsored by the Frontotemporal Degeneration Treatment Study Group, a collaborative group of academic and industry researchers that is devoted to developing treatments for FTD. This article discusses the current status of FTD clinical research that is relevant to the conduct of clinical trials, and why FTD research may be an attractive pathway for developing therapies for neurodegenerative disorders. The clinical and molecular features of FTD, including rapid disease progression and relatively pure molecular pathology, suggest that there are advantages to developing drugs for FTD as compared with other dementias. FTD qualifies as orphan indication, providing additional advantages for drug development. Two recent sets of consensus diagnostic criteria will facilitate the identification of patients with FTD, and a variety of neuropsychological, functional, and behavioral scales have been shown to be sensitive to disease progression. Moreover, quantitative neuroimaging measurements demonstrate progressive brain atrophy in FTD at rates that may surpass Alzheimer's disease. Finally, the similarities between FTD and other neurodegenerative diseases with drug development efforts already underway suggest that FTD researchers will be able to draw on this experience to create a road map for FTD drug development. We conclude that FTD research has reached sufficient maturity to pursue clinical development of specific FTD therapies.

PET Imaging and biodistribution of chemically modified bacteriophage MS2.

The fields of nanotechnology and medicine have merged in the development of new imaging and drug delivery agents based on nanoparticle platforms. As one example, a mutant of bacteriophage MS2 can be differentially modified on the exterior and interior surfaces for the concurrent display of targeting functionalities and payloads, respectively. In order to realize their potential for use in in vivo applications, the biodistribution and circulation properties of this class of agents must first be investigated. A means of modulating and potentially improving the characteristics of nanoparticle agents is the appendage of PEG chains. Both MS2 and MS2-PEG capsids possessing interior DOTA chelators were labeled with (64)Cu and injected intravenously into mice possessing tumor xenografts. Dynamic imaging of the agents was performed using PET-CT on a single animal per sample, and the biodistribution at the terminal time point (24 h) was assessed by gamma counting of the organs ex vivo for 3 animals per agent. Compared to other viral capsids of similar size, the MS2 agents showed longer circulation times. Both MS2 and MS2-PEG bacteriophage behaved similarly, although the latter agent showed significantly less uptake in the spleen. This effect may be attributed to the ability of the PEG chains to mask the capsid charge. Although the tumor uptake of the agents may result from the enhanced permeation and retention (EPR) effect, selective tumor imaging may be achieved in the future by using exterior targeting groups.

Discovery of (5S,6S,9R)-5-amino-6-(2,3-difluorophenyl)-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-9-yl 4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-1-yl)piperidine-1-carboxylate (BMS-927711): an oral calcitonin gene-related peptide (CGRP) antagonist in clinical trials for treating migraine.

Calcitonin gene-related peptide (CGRP) receptor antagonists have demonstrated clinical efficacy in the treatment of acute migraine. Herein, we describe the design, synthesis, and preclinical characterization of a highly potent, oral CGRP receptor antagonist BMS-927711 (8). Compound 8 has good oral bioavailability in rat and cynomolgus monkey, attractive overall preclinical properties, and shows dose-dependent activity in a primate model of CGRP-induced facial blood flow. Compound 8 is presently in phase II clinical trials.

A placebo-controlled, multiple ascending dose study to evaluate the safety, pharmacokinetics and pharmacodynamics of avagacestat (BMS-708163) in healthy young and elderly subjects.

BACKGROUND AND OBJECTIVES: Avagacestat is an orally active γ-secretase inhibitor that selectively inhibits amyloid ß (Aß) synthesis in cell culture and animal models. The objective of the current study was to assess the pharmacokinetics, pharmacodynamics, safety and tolerability of multiple doses of avagacestat over 28 days in healthy young men and elderly men and women in a placebo-controlled, sequential-panel, ascending multiple-dose study. METHODS: Thirty-three young men were assigned to four serial dose groups of avagacestat 15, 50, 100 or 150 mg (n = 6-7 per dose), or placebo (n = 2 per dose panel; 8 subjects total) once daily for 28 days. Elderly men and women were assigned to serial dose groups of avagacestat 50 mg and then 100 mg (n = 7 men, 6 women) or placebo (n = 2 men, 2 women) once daily for 14 days per dose level. RESULTS: Avagacestat was rapidly absorbed, had a terminal elimination half-life of 38-65 h, and reached a steady-state concentration by day 10 of daily dosing. Exposure in young subjects increased in proportion to dose. There were no apparent differences in steady-state area under the plasma concentration-time curve between young and elderly subjects; however, elderly subjects demonstrated a higher maximum plasma concentration for avagacestat. Doses of avagacestat >50 mg/day reduced steady-state trough concentrations of CSF Aß(1-38), Aß(1-40) and Aß(1-42) in a dose-dependent fashion over 28 days of daily dosing. There were no signs of potential Notch-related dose-limiting toxicities. CONCLUSION: The results support continued evaluation of avagacestat in an elderly target population with predementia and mild to moderate Alzheimer's disease.