Why so few drugs for Alzheimer's disease? Are methods failing drugs?

NaI/PPh3-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

A practical NaI/PPh3-catalyzed decarboxylative radical cascade cyclization of N-arylacrylamides with redox-active esters is described, which is mediated by visible light irradiation. A wide range of substrates bearing different substituents and derived from ubiquitous carboxylic acids, including α-amino acids, were synthesized and examined under this very mild, efficient, and cost effective transition-metal-free synthetic method. These afforded various functionalized oxindoles featuring a C3 quaternary stereogenic center. Mechanistic experiments suggest a radical mechanism.

Translational Scoring of Candidate Treatments for Alzheimer's Disease: A Systematic Approach

BACKGROUND

There are many failures in treatment development for Alzheimer's disease (AD). Some of these failures are the result of development programs that lacked critical information about candidate drugs as these were advanced from one phase of development to the next. Translational scoring (TS) has been proposed as a means of increasing the rigor with which treatment development programs are executed. Previously, these approaches were not specific to AD or to the phase of drug development. Detailed information on the characteristics needed to advance a candidate agent from one phase to the next is the basis for success in subsequent phases.

SUMMARY

The TS approach is presented with a score range of 0-25 for agents entering phases 1, 2, and 3 of development and those that have completed phase 3 and are being considered for regulatory review. Each phase has 5 essential categories scored from 0-5 indicating the completeness of the data available when the agent is being considered for promotion to the next phase. Lower scores suggest that the development program should be reexamined for missing information while higher scores increase the confidence that the agent has the potential to succeed in the next phase. Scoring guidelines are provided and examples of scores for drugs in recent development programs are provided to illustrate the principles of TS. Key Messages: Successful development of drugs for AD treatment requires disciplined informed decision-making at each phase of development. TS is a methodology for more rigorous drug development to help ensure that inadequately characterized drugs are not advanced and that the development platform at each phase is optimal to support success at the next phase.

HGF Mediates Clinical-Grade Human Umbilical Cord-Derived Mesenchymal Stem Cells Improved Functional Recovery in a Senescence-Accelerated Mouse Model of Alzheimer's Disease

Stem cells have emerged as a potential therapy for a range of neural insults, but their application in Alzheimer's disease (AD) is still limited and the mechanisms underlying the cognitive benefits of stem cells remain to be elucidated. Here, the effects of clinical-grade human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) on the recovery of cognitive ability in SAMP8 mice, a senescence-accelerated mouse model of AD is explored. A functional assay identifies that the core functional factor hepatocyte growth factor (HGF) secreted from hUC-MSCs plays critical roles in hUC-MSC-modulated recovery of damaged neural cells by down-regulating hyperphosphorylated tau, reversing spine loss, and promoting synaptic plasticity in an AD cell model. Mechanistically, structural and functional recovery, as well as cognitive enhancements elicited by exposure to hUC-MSCs, are at least partially mediated by HGF in the AD hippocampus through the activation of the cMet-AKT-GSK3β signaling pathway. Taken together, these data strongly implicate HGF in mediating hUC-MSC-induced improvements in functional recovery in AD models.

Clinical trial design for progressive MS trials

The design of clinical trials is a key aspect to maximizing the possibility to detect a treatment effect. This fact is particularly challenging in progressive multiple sclerosis (PMS) studies due to the uncertainty about the right target and/or outcome in phase-2 studies. The aim of this review is to evaluate the current challenges facing the design of clinical trials for PMS. The selection of patients, the instrumental and clinical outcomes that can be used in PMS trials, and issues in their design will be covered in this report.

Does traumatic brain injury hold the key to the Alzheimer's disease puzzle?

INTRODUCTION

Neurodegenerative disorders have been a graveyard for hundreds of well-intentioned efforts at drug discovery and development. Concussion and other traumatic brain injuries (TBIs) and Alzheimer's disease (AD) share many overlapping pathologies and possible clinical links.

METHODS

We searched the literature since 1995 using MEDLINE and Google Scholar for the terms concussion, AD, and shared neuropathologies. We also studied a TBI animal model as a supplement to transgenic (Tg) mouse AD models for evaluating AD drug efficacy by preventing neuronal losses. To evaluate TBI/AD pathologies and neuronal self-induced cell death (apoptosis), we are studying brain extracellular vesicles in plasma and (-)-phenserine pharmacology to probe, in animal models of AD and humans, apoptosis and pathways common to concussion and AD.

RESULTS

Neuronal cell death and a diverse and significant pathological cascade follow TBIs. Many of the developing pathologies are present in early AD. The use of an animal model of concussion as a supplement to Tg mice provides an indication of an AD drug candidate's potential for preventing apoptosis and resulting progression toward dementia in AD. This weight drop supplementation to Tg mouse models, the experimental drug (-)-phenserine, and plasma-derived extracellular vesicles enriched for neuronal origin to follow biomarkers of neurodegenerative processes, each and in combination, show promise as tools useful for probing the progression of disease in AD, TBI/AD pathologies, apoptosis, and drug effects on rates of apoptosis both preclinically and in humans. (-)-Phenserine both countered many subacute post-TBI pathologies that could initiate clinical AD and, in the concussion and other animal models, showed evidence consistent with direct inhibition of neuronal preprogrammed cell death in the presence of TBI/AD pathologies.

DISCUSSION

These findings may provide support for expanding preclinical Tg mouse studies in AD with a TBI weight drop model, insights into the progression of pathological targets, their relations to apoptosis, and timing of interventions against these targets and apoptosis. Such studies may demonstrate the potential for drugs to effectively and safely inhibit preprogrammed cell death as a new drug development strategy for use in the fight to defeat AD.

Poor Safety and Tolerability Hamper Reaching a Potentially Therapeutic Dose in the Use of Thalidomide for Alzheimer's Disease: Results from a Double-Blind, Placebo-Controlled Trial

INTRODUCTION

To date there is no cure for Alzheimer's disease (AD). After amyloid beta immunotherapies have failed to meet primary endpoints of slowing cognitive decline in AD subjects, the inhibition of the beta-secretase BACE1 appears as a promising therapeutic approach. Pre-clinical data obtained in APP23 mice suggested that the anti-cancer drug thalidomide decreases brainBACE1 and Aβ levels. This prompted us to develop an NIH-supported Phase IIa clinical trial to test the potential of thalidomide for AD. We hypothesized that thalidomide can decrease or stabilize brain amyloid deposits, which would result in slower cognitive decline in drug- versus placebo-treated subjects.

METHODS

This was a 24-week, randomized, double-blind, placebo-controlled, parallel group study with escalating dose regimen of thalidomide with a target dose of 400mg daily in patients with mild to moderate AD. The primary outcome measures were tolerability and cognitive performance assessed by a battery of tests.

RESULTS

A total of 185 subjects have been pre-screened, out of which25 were randomized. Mean age of the sample at baseline was 73.64 (±7.20) years; mean education was 14.24 (±2.3) years; mean MMSE score was 21.00 (±5.32); and mean GDS score was 2.76 (±2.28).Among the 25 participants, 14 (56%) terminated early due to adverse events, dramatically decreasing the power of the study. In addition, those who completed the study (44%) never reached the estimated therapeutic dose of 400 mg/day thalidomide because of reported adverse events. The cognitive data showed no difference between the treated and placebo groups at the end of the trial.

CONCLUSION

This study demonstrates AD patients have poor tolerability for thalidomide, and are unable to reach a therapeutic dose felt to be sufficient to have effects on BACE1. Because of poor tolerability, this study failed to demonstrate a beneficial effect on cognition.

Why do trials for Alzheimer's disease drugs keep failing? A discontinued drug perspective for 2010-2015

INTRODUCTION

There are dozens of drugs in development for AD with billions of dollars invested. Despite the massive investment in AD drugs and a burgeoning pipeline, there have been more setbacks and failures than treatment successes. Areas covered: The classes of drugs that have failed to date include the monoclonal antibodies, the gamma secretase inhibitors, dimebon, neurochemical enhancers, and one tau drug. Data for these compounds were sought through a PubMed search and a clinicaltrials.gov search. Expert opinion: The obvious question to be posed is: Why are they failing? Is the treatment of symptomatic dementia too late? Are the therapeutic targets incorrect? Are the clinical methodologies imprecise, misleading, or inaccurate? This review summarizes the drugs that have failed during 2010-2015 and offers possible theories as to why they have failed.

Re-Engineering Alzheimer Clinical Trials: Global Alzheimer's Platform Network

Alzheimer's disease (AD) drug development is costly, time-consuming, and inefficient. Trial site functions, trial design, and patient recruitment for trials all require improvement. The Global Alzheimer Platform (GAP) was initiated in response to these challenges. Four GAP work streams evolved in the US to address different trial challenges: 1) registry-to-cohort web-based recruitment; 2) clinical trial site activation and site network construction (GAP-NET); 3) adaptive proof-of-concept clinical trial design; and 4) finance and fund raising. GAP-NET proposes to establish a standardized network of continuously funded trial sites that are highly qualified to perform trials (with established clinical, biomarker, imaging capability; certified raters; sophisticated management system. GAP-NET will conduct trials for academic and biopharma industry partners using standardized instrument versions and administration. Collaboration with the Innovative Medicines Initiative (IMI) European Prevention of Alzheimer's Disease (EPAD) program, the Canadian Consortium on Neurodegeneration in Aging (CCNA) and other similar international initiatives will allow conduct of global trials. GAP-NET aims to increase trial efficiency and quality, decrease trial redundancy, accelerate cohort development and trial recruitment, and decrease trial costs. The value proposition for sites includes stable funding and uniform training and trial execution; the value to trial sponsors is decreased trial costs, reduced time to execute trials, and enhanced data quality. The value for patients and society is the more rapid availability of new treatments for AD.

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

The aim of this review is to provide an update on the current use of cyclodextrins against organophosphorus compound intoxications. Organophosphorus pesticides and nerve agents play a determinant role in the inhibition of cholinesterases. The cyclic structure of cyclodextrins and their toroidal shape are perfectly suitable to design new chemical scavengers able to trap and hydrolyze the organophosphorus compounds before they reach their biological target.

The need for thorough phase II studies in medicines development for Alzheimer's disease

An important factor in the universal failure in phase III trials in mild to moderate Alzheimer’s disease in the past decade is the lack of phase II clinical data prior to entering phase III, with common reliance on biomarker results alone. Conduction of two learn-confirm cycles according to the Sheiner model would allow go/no-go decision making to include reliable clinical efficacy data prior to conducting phase III and would likely bring the rate of late stage failure more into line with that of other neurological indications. In studies in earlier disease stages, combined phase IIB/III adaptive approaches merit consideration in view of the long timelines of each study, though advantages and disadvantages of this approach versus the classical development pathway still need careful assessment.

What can triumphs and tribulations from drug research in Alzheimer's disease tell us about the development of psychotropic drugs in general?

Drug development for psychiatric disorders has almost ground to a halt. Some newer drugs are better tolerated or safer than older ones, but none is more effective. Years of failure in preventing or delaying the onset of illness, ameliorating symptoms, lowering suicide rates, or improving quality of life has put the commercial investments that had previously funded drug development at risk. To promote the development of psychiatric drugs with greater efficacy, we need to improve the way we bring potentially beneficial drugs to market. We need to acknowledge, as has been done in other specialties, that people differ in their response to drugs. Psychiatric drug research needs to be grounded in a better understanding of molecular brain mechanisms, neural circuits, and their relations to clinical disease. With this understanding, drugs need to be more precisely directed at specific brain targets. In psychiatric drug development, government, industry, regulatory bodies, and academia should realign to ensure medical science is used in the best interests of patients.

Linking Alzheimer's disease and type 2 diabetes mellitus via aberrant insulin signaling and inflammation

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are two progressive and devastating health disorders afflicting millions of people worldwide. The probability and incidence of both have increased considerably in recent years consequent to increased longevity and population growth. Progressively more links are being continuously found between inflammation and central nervous system disorders like AD, Parkinson's disease, Huntington's disease, motor neuron disease, multiple sclerosis, stroke, traumatic brain injury and even cancers of the nervous tissue. The depth of the relationship depends on the timing and extent of anti- or pro-inflammatory gene expression. Inflammation has also been implicated in T2DM. Misfolding and fibrillization (of tissue specific and/or non-specific proteins) are features common to both AD and T2DM and are induced by as well as contribute to inflammation and stress (oxidative/ glycation). This review appraises the roles of inflammation and abnormalities in the insulin signaling system as important shared features of T2DM and AD. The capacity of anti-cholinesterases in reducing the level of certain common inflammatory markers in particular if they may provide therapeutic potential to mitigate awry mechanisms leading to AD.

Lessons from a BACE1 inhibitor trial: off-site but not off base

Alzheimer's disease (AD) is characterized by formation of neuritic plaque primarily composed of a small filamentous protein called amyloid-β peptide (Aβ). The rate-limiting step in the production of Aβ is the processing of Aβ precursor protein (APP) by β-site APP-cleaving enzyme (BACE1). Hence, BACE1 activity plausibly plays a rate-limiting role in the generation of potentially toxic Aβ within brain and the development of AD, thereby making it an interesting drug target. A phase II trial of the promising LY2886721 inhibitor of BACE1 was suspended in June 2013 by Eli Lilly and Co., due to possible liver toxicity. This outcome was apparently a surprise to the study's team, particularly since BACE1 knockout mice and mice treated with the drug did not show such liver toxicity. Lilly proposed that the problem was not due to LY2886721 anti-BACE1 activity. We offer an alternative hypothesis, whereby anti-BACE1 activity may induce apparent hepatotoxicity through inhibiting BACE1's processing of β-galactoside α-2,6-sialyltransferase I (STGal6 I). In knockout mice, paralogues, such as BACE2 or cathepsin D, could partially compensate. Furthermore, the short duration of animal studies and short lifespan of study animals could mask effects that would require several decades to accumulate in humans. Inhibition of hepatic BACE1 activity in middle-aged humans would produce effects not detectable in mice. We present a testable model to explain the off-target effects of LY2886721 and highlight more broadly that so-called off-target drug effects might actually represent off-site effects that are not necessarily off-target. Consideration of this concept in forthcoming drug design, screening, and testing programs may prevent such failures in the future.

Alzheimer disease therapy--moving from amyloid-β to tau

Disease-modifying treatments for Alzheimer disease (AD) have focused mainly on reducing levels of amyloid-β (Aβ) in the brain. Some compounds have achieved this goal, but none has produced clinically meaningful results. Several methodological issues relating to clinical trials of these agents might explain this failure; an additional consideration is that the amyloid cascade hypothesis--which places amyloid plaques at the heart of AD pathogenesis--does not fully integrate a large body of data relevant to the emergence of clinical AD. Importantly, amyloid deposition is not strongly correlated with cognition in multivariate analyses, unlike hyperphosphorylated tau, neurofibrillary tangles, and synaptic and neuronal loss, which are closely associated with memory deficits. Targeting tau pathology, therefore, might be more clinically effective than Aβ-directed therapies. Furthermore, numerous immunization studies in animal models indicate that reduction of intracellular levels of tau and phosphorylated tau is possible, and is associated with improved cognitive performance. Several tau-related vaccines are in advanced preclinical stages and will soon enter clinical trials. In this article, we present a critical analysis of the failure of Aβ-directed therapies, discuss limitations of the amyloid cascade hypothesis, and suggest the potential value of tau-targeted therapy for AD.

Was phenserine a failure or were investigators mislead by methods?

Over 200 Alzheimer's disease (AD) drug candidates have failed in development, and other neuropsychiatric trials have had their validity compromised. Studies suggest that methodological errors can be a source for these compromises and failures. We gained access to documentation for phenserine, an experimental AD drug that reached phase III clinical trials. The 06 Phase III trial was cited by the developers as grounds for their abandonment of the development. We compared evidence for interventions to control methodological errors and grounds for moving through phases of drug development to 40 other randomly selected AD developments we had studied. We analyzed methods and conditions of the 06 phenserine clinical trial, for biases able to account for its abandonment during development. The phenserine development failed to control error sources able to affect the outcomes. There are statistically significant relationships in the 06 clinical trial between outcomes at research sites and levels of variance, placebo group improvements and other factors. We conclude that phenserine was abandoned, at least in part, due to a clinical trial invalidated by relationships among its methods and outcomes.

Synthesis of the Alzheimer drug Posiphen into its primary metabolic products (+)-N1-norPosiphen, (+)-N8-norPosiphen and (+)-N1, N8-bisnorPosiphen, their inhibition of amyloid precursor protein, α-Synuclein synthesis, interleukin-1β release, and cholinergic action

A major pathological hallmark of Alzheimer disease (AD) is the appearance in the brain of senile plaques that are primarily composed of aggregated forms of β-amyloid peptide (Aβ) that derive from amyloid precursor protein (APP). Posiphen (1) tartrate is an experimental AD drug in current clinical trials that reduces Aβ levels by lowering the rate of APP synthesis without toxicity. To support the clinical development of Posiphen (1) and elucidate its efficacy, its three major metabolic products, (+)-N1-norPosiphen (15), (+)-N8-norPosiphen (17) and (+)-N1, N8-bisnorPosiphen (11), were required in high chemical and optical purity. The efficient transformation of Posiphen (1) into these metabolic products, 15, 17 and 11, is described. The biological activity of these metabolites together with Posiphen (1) and its enantiomer, the AD drug candidate (-)-phenserine (2), was assessed against APP,α-synuclein and classical cholinergic targets. All the compounds potently inhibited the generation of APP and α-synuclein in neuronal cultures. In contrast, metabolites 11 and 15, and (-)-phenserine (2) but not Posiphen (1) or 17, possessed acetyl cholinesterase inhibitory action and no compounds bound either nicotinic or muscarinic receptors. As Posiphen (1) lowered CSF markers of inflammation in a recent clinical trial, the actions of 1 and 2 on proinflammatory cytokine interleukin (IL)-1β release human peripheral blood mononuclear cells was evaluated, and found to be potently inhibited by both agents.

Fire in the ashes: can failed Alzheimer's disease drugs succeed with second chances?

BACKGROUND

Since Cognex, more than 200 Alzheimer's disease (AD) drug candidates have failed. Investigations have identified vulnerabilities of these AD drug developments to methodological errors. (-)-Phenserine has been discussed as possibly failing due to flawed methods and practices in development.

METHODS

We analyzed documentation of (-)-phenserine's development for vulnerabilities to errors and designed interventions for a redevelopment that could provide fair or unbiased assessments of (-)-phenserine target engagement, target relevance for human diseases, and adequate presumptive evidence of efficacy as a therapeutic for one or more diagnoses to justify registration-required clinical trials.

RESULTS

Similar to studies of 40 other AD developments, with (-)-phenserine, we found little evidence of preemptive interventions against potentially invalidating errors, grounds to judge progress in development through stages as not scientifically justifiable, and variance excess and placebo group improvements as capable of accounting for outcomes from various studies in the development. We propose to compare a redevelopment resourced to counter these deficiencies with the original development as historical control to evaluate further our hypothesis that errors in development accounted for the (-)-phenserine failure, specifically, and other AD drug failures, potentially.

CONCLUSIONS

We find support for our earlier proposal that (-)-phenserine did not fail, but the methods of development did fail, to provide conditions where efficacy could be tested. We propose that redevelopment under conditions aimed to correct methodological deficiencies common in AD drug developments will successfully test efficacy for (-)-phenserine and hopefully lead to a disease-modifying addition to the AD therapeutic armamentarium.

J-147 a Novel Hydrazide Lead Compound to Treat Neurodegeneration: CeeTox™ Safety and Genotoxicity Analysis

J-147 is a broad spectrum neuroprotective phenyl hydrazide compound with significant neurotrophic properties related to the induction of brain-derived neurotrophic factor (BDNF). Because this molecule is pleiotropic, it may have substantial utility in the treatment of a wide range of neurodegenerative diseases including acute ischemic stroke (AIS), traumatic brain injury(TBI), and Alzheimer’s disease(AD) where both neuroprotection and neurotrophism would be beneficial. Because of the pleiotropic actions of J-147, we sought to determine the safety profile of the drug using multiple assay analysis.

For CeeTox analyses, we used a rat hepatoma cell line (H4IIE) resulted in estimated C_Tox value (i.e.: sustained concentration expected to produce toxicity in a 14 day repeat dosing study) of 90 μM for J-147. The CeeTox panel shows that J-147 produced some adverse effects on cellular activities, in particular mitochondrial function, but only with high concentrations of the drug. J-147 was also not genetoxic with or without Aroclor-1254 treatment.

For J-147, based upon extensive neuroprotection assay data previously published, and the CeeTox assay (C_Tox value of 90 μM) in this study, we estimated in vitro neuroprotection efficacy (EC₅₀ range 0.06–0.115 μM)/toxicity ratio is 782.6–1500 fold and the neurotrophism (EC₅₀ range 0.025 μM)/toxicity ratio is 3600, suggesting that there is a significant therapeutic safety window for J-147 and that it should be further developed as a novel neuroprotective-neurotrophic agent to treat neurodegenerative disease taking into account current National Institute of Neurological Disorders and Stroke (NINDS) RIGOR guidelines.

Cholinesterase inhibitors improve both memory and complex learning in aged beagle dogs

Similar to patients with Alzheimer's disease (AD), dogs exhibit age-dependent cognitive decline, amyloid-β (Aβ) pathology, and evidence of cholinergic hypofunction. The present study sought to further investigate the role of cholinergic hypofunction in the canine model by examining the effect of the cholinesterase inhibitors phenserine and donepezil on performance of two tasks, a delayed non-matching-to-position task (DNMP) designed to assess working memory, and an oddity discrimination learning task designed to assess complex learning, in aged dogs. Phenserine (0.5 mg/kg; PO) significantly improved performance on the DNMP at the longest delay compared to wash-out and partially attenuated scopolamine-induced deficits (15 μg/kg; SC). Phenserine also improved learning on a difficult version of an oddity discrimination task compared to placebo, but had no effect on an easier version. We also examined the effects of three doses of donepezil (0.75, 1.5, and 6 mg/kg; PO) on performance of the DNMP. Similar to the results with phenserine, 1.5 mg/kg of donepezil improved performance at the longest delay compared to baseline and wash-out, indicative of memory enhancement. These results further extend the findings of cholinergic hypofunction in aged dogs and provide pharmacological validation of the canine model with a cholinesterase inhibitor approved for use in AD. Collectively, these studies support utilizing the aged dog in future screening of therapeutics for AD, as well as for investigating the links among cholinergic function, Aβ pathology, and cognitive decline.

Advances in microRNA experimental approaches to study physiological regulation of gene products implicated in CNS disorders

The central nervous system (CNS) is a remarkably complex organ system, requiring an equally complex network of molecular pathways controlling the multitude of diverse, cellular activities. Gene expression is a critical node at which regulatory control of molecular networks is implemented. As such, elucidating the various mechanisms employed in the physiological regulation of gene expression in the CNS is important both for establishing a reference for comparison to the diseased state and for expanding the set of validated drug targets available for disease intervention. MicroRNAs (miRNAs) are an abundant class of small RNA that mediates potent inhibitory effects on global gene expression. Recent advances have been made in methods employed to study the contribution of these miRNAs to gene expression. Here we review these latest advances and present a methodological workflow from the perspective of an investigator studying the physiological regulation of a gene of interest. We discuss methods for identifying putative miRNA target sites in a transcript of interest, strategies for validating predicted target sites, assays for detecting miRNA expression, and approaches for disrupting endogenous miRNA function. We consider both advantages and limitations, highlighting certain caveats that inform the suitability of a given method for a specific application. Through careful implementation of the appropriate methodologies discussed herein, we are optimistic that important discoveries related to miRNA participation in CNS physiology and dysfunction are on the horizon.

Synergistic inhibition of butyrylcholinesterase by galantamine and citalopram

BACKGROUND

Many persons with Alzheimer's disease (AD) treated with galantamine appear to receive additional cognitive benefit from citalopram. Both drugs inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). These enzymes co-regulate acetylcholine catabolism. In AD brain, AChE is diminished while BuChE is not, suggesting BuChE inhibition may be important in raising acetylcholine levels. BuChE is subject to activation at high acetylcholine levels reached at the synaptic cleft. The present study explores one way combining galantamine and citalopram could be beneficial in AD.

METHODS

Spectrophotometric studies of BuChE catalysis in the absence or presence of galantamine or citalopram or both, were performed using the Ellman method. Data analysis involved expansion of our previous equation describing BuChE catalysis.

RESULTS

Galantamine almost completely inhibited BuChE at low substrate concentrations (V(S)=43.6 μM/min; V(S(gal))=0.34 μM/min) without influencing the substrate-activated form of the enzyme (V(SS)=64.0 μM/min;V(SS(gal))=62.3 μM/min). Conversely, citalopram inhibited both un-activated (V(S)=43.6 μM/min; V(S(cit))=10.2 μM/min) and substrate-activated (V(SS)=64.0 μM/min; V(SS(cit))=47.3 μM/min) forms of BuChE. Combined galantamine and citalopram increased inhibition of un-activated BuChE (V(S)=43.6 μM/min; V(S(gal)(cit))=2.73 μM/min) and substrate-activated form (V(SS)=64.0 μM/min; V(SS(gal)(cit))=42.2 μM/min).

CONCLUSION

Citalopram and galantamine produce a combined inhibition of BuChE that is considered to be synergistic.

GENERAL SIGNIFICANCE

Clinical benefit from combined galantamine and citalopram may be related to a synergistic inhibition of BuChE, facilitating cholinergic neurotransmission. This emphasizes the importance of further study into use of drug combinations in AD treatment.

Functional activity of the novel Alzheimer's amyloid β-peptide interacting domain (AβID) in the APP and BACE1 promoter sequences and implications in activating apoptotic genes and in amyloidogenesis

Amyloid-β peptide (Aβ) plaque in the brain is the primary (post mortem) diagnostic criterion of Alzheimer's disease (AD). The physiological role(s) of Aβ are poorly understood. We have previously determined an Aβ interacting domain (AβID) in the promoters of AD-associated genes (Maloney and Lahiri, 2011. Gene. 15,doi:10.1016/j.gene.2011.06.004. epub ahead of print.). This AβID interacts in a DNA sequence-specific manner with Aβ. We now demonstrate novel Aβ activity as a possible transcription factor. Herein, we detected Aβ-chromatin interaction in cell culture by ChIP assay. We observed that human neuroblastoma (SK-N-SH) cells treated with FITC conjugated Aβ1-40 localized Aβ to the nucleus in the presence of H2O2-mediated oxidative stress. Furthermore, primary rat fetal cerebrocortical cultures were transfected with APP and BACE1 promoter-luciferase fusions, and rat PC12 cultures were transfected with polymorphic APP promoter-CAT fusion clones. Transfected cells were treated with different Aβ peptides and/or H2O2. Aβ treatment of cell cultures produced a DNA sequence-specific response in cells transfected with polymorphic APP clones. Our results suggest the Aβ peptide may regulate its own production through feedback on its precursor protein and BACE1, leading to amyloidogenesis in AD.

Phenserine efficacy in Alzheimer's disease

To gather preliminary evidence in Alzheimer's disease (AD) for the efficacy of phenserine, a non-competitive acetylcholinesterase inhibitor that has independent modulatory effects on amyloid-β generation, a 12-week comparison of patients receiving phenserine (10 and 15 mg BID) or placebo was conducted under double-blind conditions. Patients who completed 12 weeks of the double-blind before others were continued in the double-blind to determine longer-term treatment effects. At 12 weeks, mean ADAS-cog (AD assessment scale-cognitive) changes from baseline were -2.5 and -1.9 for high-dose phenserine (n=83) and placebo (n=81) groups, respectively, a non-statistically significant improvement for the high-dose phenserine group relative to placebo. CIBIC+ (clinician's interview based impression of change + caregiver's input) values for the high-dose and placebo groups were similar at 12 weeks. For patients who received more than 12 weeks of therapy, the ADAS-cog changes were -3.18 and -0.66 for the high-dose phenserine (n=52) and placebo (n=63) groups, respectively, a difference achieving statistical significance (p=0.0286). After 12 weeks, CIBIC+ values were 3.59 and 3.95 for the high-dose (n=54) and placebo (n=66) groups respectively (p=0.0568). These results from this short-term study are consistent with phenserine potentially benefiting mild to moderate Alzheimer's disease symptomatically but do not address possible amyloid metabolic mediated effects on disease processes in AD.

Lost in translation: neuropsychiatric drug development

Recent studies have identified troubling method and practice lapses in neuropsychiatric drug developments. These problems have resulted in errors that are of sufficient magnitude to invalidate clinical trial data and interpretations. We identify two potential sources for these difficulties: investigators selectively choosing scientific practices for demonstrations of efficacy in human-testing phases of drug development and investigators failing to anticipate the needs of practitioners who must optimize treatment for the individual patient. When clinical investigators neglect to use clinical trials as opportunities to test hypotheses of disease mechanisms in humans, the neuropsychiatric knowledge base loses both credibility and scope. When clinical investigators do not anticipate the need to translate discoveries into applications, the practitioner cannot provide optimal care for the patient. We conclude from this evidence that clinical trials, and other aspects of neuropsychiatric drug development, must adopt more practices from basic science and show greater responsiveness to conditions of clinical practice. We feel that these changes are necessary to overcome current threats to the validity and utility of studies of neurological and psychiatric drugs.