Biomarker candidates of neurodegeneration in Parkinson's disease for the evaluation of disease-modifying therapeutics

Reliable biomarkers that can be used for early diagnosis and tracking disease progression are the cornerstone of the development of disease-modifying treatments for Parkinson’s disease (PD). The German Society of Experimental and Clinical Neurotherapeutics (GESENT) has convened a Working Group to review the current status of proposed biomarkers of neurodegeneration according to the following criteria and to develop a consensus statement on biomarker candidates for evaluation of disease-modifying therapeutics in PD. The criteria proposed are that the biomarker should be linked to fundamental features of PD neuropathology and mechanisms underlying neurodegeneration in PD, should be correlated to disease progression assessed by clinical rating scales, should monitor the actual disease status, should be pre-clinically validated, and confirmed by at least two independent studies conducted by qualified investigators with the results published in peer-reviewed journals. To date, available data have not yet revealed one reliable biomarker to detect early neurodegeneration in PD and to detect and monitor effects of drug candidates on the disease process, but some promising biomarker candidates, such as antibodies against neuromelanin, pathological forms of α-synuclein, DJ-1, and patterns of gene expression, metabolomic and protein profiling exist. Almost all of the biomarker candidates were not investigated in relation to effects of treatment, validated in experimental models of PD and confirmed in independent studies.

Memantine in moderate to severe Alzheimer's disease: a meta-analysis of randomised clinical trials

The efficacy of memantine in Alzheimer's disease (AD) has been investigated in multiple randomised, placebo-controlled phase III trials. Recently, the indication label for memantine in Europe was extended to cover patients with moderate to severe AD, i.e. Mini-Mental State Exam total scores below 20. The efficacy data for memantine in this patient subgroup has been summarised by a meta-analysis of 1,826 patients in six trials. Efficacy was assessed using measures of global status (Clinician's Interview-Based Impression of Change Plus Caregiver Input), cognition (Alzheimer's Disease Assessment Scale - Cognitive Subscale, or Severe Impairment Battery), function (Alzheimer's Disease Cooperative Study Activities of Daily Living 19- or 23-item scale), and behaviour (Neuropsychiatric Inventory). Results (without replacement of missing values) showed statistically significant effects for memantine (vs. placebo) in each domain. Memantine was well tolerated, and the overall incidence rates of adverse events were comparable to placebo. This meta-analysis supports memantine's clinically relevant efficacy in patients with moderate to severe AD.

Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system--too little activation is bad, too much is even worse

The neurotransmitter glutamate activates several classes of metabotropic receptor and three major types of ionotropic receptor--alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA). The involvement of glutamate mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD) is finding increasing scientific acceptance. Central to this hypothesis is the assumption that glutamate receptors, in particular of the NMDA type, are overactivated in a tonic rather than a phasic manner. Such continuous, mild, chronic activation ultimately leads to neuronal damage/death. Additionally, impairment of synaptic plasticity (learning) may result not only from neuronal damage per se but may also be a direct consequence of this continuous, non-contingent NMDA receptor activation. Complete NMDA receptor blockade has also been shown to impair neuronal plasticity, thus, both hypo- and hyperactivity of the glutamatergic system leads to dysfunction. Memantine received marketing authorization from the EMEA (European Medicines Agency) for the treatment of moderate to severe AD in Europe and was subsequently also approved by the FDA (Food and Drug Administration) for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive NMDA receptor antagonist with strong voltage-dependency and fast kinetics. This review summarizes existing hypotheses on the mechanism of action (MOA) of memantine in an attempt to understand how the accepted interaction with NMDA receptors could allow memantine to provide both neuroprotection and reverse deficits in learning/memory by the same MOA.

A 24-week open-label extension study of memantine in moderate to severe Alzheimer disease

BACKGROUND

This study is an extension of a 28-week, randomized, double-blind, placebo-controlled study of memantine in 252 patients with moderate to severe Alzheimer disease.

OBJECTIVE

To evaluate long-term memantine treatment in moderate to severe Alzheimer disease.

DESIGN, SETTING, AND PATIENTS

Open-label, 24-week extension trial. Raters remained blind to the patients' initial study treatment. Patients (n = 175) were enrolled from the previous double-blind study in an outpatient setting.

INTERVENTION

Twenty mg of memantine was given daily.

MAIN OUTCOME MEASURES

Efficacy assessments from the double-blind study were continued and safety parameters were monitored.

RESULTS

Patients who switched to memantine treatment from their previous placebo therapy experienced a significant benefit in all main efficacy assessments (functional, global, and cognitive) relative to their mean rate of decline with placebo treatment during the double-blind period (P<.05). The completion rate for the extension phase of the study was high (78%) and the favorable adverse event profile for memantine therapy was similar to that seen in the double-blind study.

CONCLUSION

These results extend previous findings that demonstrated the efficacy and safety of memantine in the treatment of patients with moderate to severe Alzheimer disease.

Memantine in vascular dementia

The uncompetitive N-methyl-D-aspartate (NMDA) antagonist memantine was tested against placebo in two randomized controlled trials. In total, 900 patients suffering from mild-to-moderate "probable" VaD (according to NINDS-AIREN criteria) were included. In these prospective, 2-arm parallel, multicenter trials conducted in the United Kingdom (MMM500) and in France (MMM300), patients suffering from "probable" vascular dementia (according to NINDS-AIREN criteria) were recruited. Active treatment in both trials was memantine at the standard daily dose of 10 mg b.i.d. The cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog) was a primary endpoint in both trials, and in both trials a statistically significant difference was seen between treatment groups after 28 weeks. In a pooled analysis of the data, various subgroups were examined. In a first analysis, patients were stratified by their severity of dementia (measured by the MMSE total scores at baseline). In this analysis, memantine was superior to placebo in all subgroups, but the magnitude of effect was clearly more pronounced in the more severely demented patients. A second analysis stratified the patients by the neuroradiological findings at baseline ("small vessel" versus "large vessel" type of VaD). The cognitive benefit by memantine treatment was larger for the small vessel group and, interestingly, also the decline in the placebo group was faster in the small vessel patients. In these trials, memantine at a dose of 10 mg b.i.d. was safe and very well tolerated with a frequency of dropouts due to adverse events that was close to placebo.

Memantine hydrochloride: pharmacological and clinical profile

Memantine (Axura, Merz Pharmaceuticals GmbH; Ebixa, H. Lundbeck A/S, Namenda, Forest Laboratories, Inc.) is an uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist with low to moderate affinity for the (+)MK-801 binding site. It is characterized as a voltage-sensitive open-channel NMDA receptor blocker that antagonizes NMDA receptor-mediated inward currents in vitro with an IC50 of 1-3 microM. In animal models, memantine displays both neuroprotective (antiexcitotoxic) and cognition-enhancing properties at therapeutically relevant concentrations. The strong voltage dependency and rapid blocking/unblocking kinetics of memantine are thought to be the basis for its excellent clinical tolerability. Recently completed clinical studies demonstrate positive effects of memantine in Alzheimer's disease both as a monotherapy and in patients receiving continuous donepezil treatment. Memantine treatment also has demonstrated significant improvement of cognitive performance in patients suffering from vascular dementia. Furthermore, the safety and tolerability of memantine in clinical trials has been excellent, with the incidence of premature withdrawals due to adverse events no greater than placebo and overall low frequencies of total adverse events. In 2002, memantine was approved by the European Medicines Agency (EMEA) for the treatment of moderately severe to severe Alzheimer's disease. More recently, memantine was approved in the US for the treatment of moderate to severe Alzheimer's disease (October 2003). Here, we review the most recent pharmacological and clinical data in dementia patients that has emerged from the systematic evaluation of memantine.

Memantine in moderate-to-severe Alzheimer's disease

BACKGROUND

Overstimulation of the N-methyl-D-aspartate (NMDA) receptor by glutamate is implicated in neurodegenerative disorders. Accordingly, we investigated memantine, an NMDA antagonist, for the treatment of Alzheimer's disease.

METHODS

Patients with moderate-to-severe Alzheimer's disease were randomly assigned to receive placebo or 20 mg of memantine daily for 28 weeks. The primary efficacy variables were the Clinician's Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus) and the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory modified for severe dementia (ADCS-ADLsev). The secondary efficacy end points included the Severe Impairment Battery and other measures of cognition, function, and behavior. Treatment differences between base line and the end point were assessed. Missing observations were imputed by using the most recent previous observation (the last observation carried forward). The results were also analyzed with only the observed values included, without replacing the missing values (observed-cases analysis).

RESULTS

Two hundred fifty-two patients (67 percent women; mean age, 76 years) from 32 U.S. centers were enrolled. Of these, 181 (72 percent) completed the study and were evaluated at week 28. Seventy-one patients discontinued treatment prematurely (42 taking placebo and 29 taking memantine). Patients receiving memantine had a better outcome than those receiving placebo, according to the results of the CIBIC-Plus (P=0.06 with the last observation carried forward, P=0.03 for observed cases), the ADCS-ADLsev (P=0.02 with the last observation carried forward, P=0.003 for observed cases), and the Severe Impairment Battery (P<0.001 with the last observation carried forward, P=0.002 for observed cases). Memantine was not associated with a significant frequency of adverse events.

CONCLUSIONS

Antiglutamatergic treatment reduced clinical deterioration in moderate-to-severe Alzheimer's disease, a phase associated with distress for patients and burden on caregivers, for which other treatments are not available.

Glutamate receptors as a target for Alzheimer's disease--are clinical results supporting the hope?

Several years after the introduction of cholinergic drugs in Alzheimer's disease therapy, other approaches for symptomatic and also disease-modifying pharmacotherapy are progressing in their development. Among these, the NMDA antagonist memantine represents the most advanced and promising agent, gifted with many years of clinical experience in Germany. This paper provides an overview of both, the novel pharmacological background and recent clinical evidence in dementia. Memantine was recently recommended for central European approval.

Measuring cognition in advanced Alzheimer's disease for clinical trials

Measurement of cognitive dysfunction and treatment response in the early stages of Alzheimer's disease (AD) has used such scales as the Mini-Mental State Examination (MMSE) and the AD Assessment Scale (ADAS). With the exception of clinical rating scales, however, there are only a few objective measures of cognition for tracking progression in advanced AD. Given renewed interest in potential therapies for advanced AD, objective measures of cognition are important for the adequate evaluation of change due to AD progression or therapy. Several cognitive measures for advanced AD are reviewed. One measure, the Severe Impairment Battery (SIB) is reviewed in detail. Preliminary analyses from a trial of memantine show significant change on the SIB in memory (p < 0.001) and visuospatial functions (p < 0.02) over six-months with a trend for language and praxis. Data from a donepezil trial also highlight the importance of accurate assessment in advanced AD.

Resource utilisation and cost analysis of memantine in patients with moderate to severe Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a devastating illness that causes enormous emotional stress to affected families and is associated with substantial medical and nonmedical costs.

OBJECTIVE

To determine the effects of 28 weeks of memantine treatment for patients with AD on resource utilisation and costs.

STUDY DESIGN AND METHODS

Multicentre, prospective, double-blind, randomised, placebo-controlled clinical trial performed in the US. The Wilcoxon-Mann-Whitney test was used to examine the resource utilisation variables and logistic regression models were used for multivariate resource utilisation analyses. Analysis of covariance (ANCOVA) models (log and non-log) were computed to examine costs from a societal perspective. All costs were calculated in 1999 US dollars.

STUDY POPULATION

Outpatients with moderate to severe AD. Overall, 252 patients received randomised treatment, and 166 patients (placebo n = 76, memantine n = 90) formed the treated-per-protocol (TPP) subset for the health economic analyses, on which the main cost analysis was based.

MAIN OUTCOME MEASURE

Resource Utilisation in Dementia (RUD) scale, measuring patient and caregiver resource utilisation, and various sources for cost calculations.

RESULTS

Controlling for baseline differences between the groups, significantly less caregiver time was needed for patients receiving memantine than for those receiving placebo (difference 51.5 hours per month; 95% CI -95.27, -7.17; p = 0.02). Analysis of residential status also favoured memantine: time to institutionalisation (p = 0.052) and institutionalisation at week 28 (p = 0.04 with the chi-square test). Total costs from a societal perspective were lower in the memantine group (difference dollars US 1089.74/month [non-overlapping 95% CI for treatment difference -1954.90, -224.58]; p = 0.01). The main differences between the groups were total caregiver costs (dollars US-823.77/month; p = 0.03) and direct nonmedical costs (dollars US-430.84/month; p = 0.07) favouring memantine treatment. Patient direct medical costs were higher in the memantine group (p < 0.01), mainly due to the cost of memantine.

CONCLUSION

Resource utilisation and total health costs were lower in the memantine group than the placebo group. The results suggest that memantine treatment of patients with moderate to severe AD is cost saving from a societal perspective.

A double-blind, placebo-controlled multicentre study of memantine in mild to moderate vascular dementia (MMM500)

The aim of the reported trial was to investigate the safety and efficacy of memantine in mild to moderate vascular dementia (VaD). This was a 28-week, double-blind, parallel, randomized controlled trial of memantine 20 mg daily versus placebo which was conducted in 54 centres in the UK. Memantine is a uncompetitive, moderate affinity N-methyl-D-aspartate receptor antagonist. Patients with a diagnosis of probable VaD and Mini Mental State Examination total scores between 10 and 22 were eligible for inclusion. Primary efficacy parameters were the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) and the Clinical Global Impression of Change (CGI-C). A total of 579 patients were randomized and 548 patients with at least one post-baseline efficacy assessment qualified for the intent-to-treat analysis. At endpoint, memantine was shown to improve cognition relative to placebo in VaD: the change of ADAS-cog from baseline differed by a mean of -1.75 points (95% confidence intervals -3.023 to -0.49) and a median of 2 points between the two groups, while CGI-C ratings showed no significant differences between treatment groups. A total of 77% of all memantine-treated patients experienced adverse event, versus 75% of the placebo-treated patients, dizziness being the most frequent adverse event (11% versus 8%, respectively). Memantine was well tolerated and safe.

Efficacy and safety of memantine in patients with mild to moderate vascular dementia: a randomized, placebo-controlled trial (MMM 300)

BACKGROUND AND PURPOSE

Based on the hypothesis of glutamate-induced neurotoxicity (excitotoxicity) in cerebral ischemia, this study examined the efficacy and tolerability of memantine, an uncompetitive N-methyl-D-aspartate antagonist, in the treatment of mild to moderate vascular dementia.

METHODS

In this multicenter, 28-week trial carried out in France, 321 patients received 10 mg/d memantine or placebo twice a day; 288 patients were valid for intent-to-treat analysis. Patients had to meet the criteria for probable vascular dementia and have a Mini-Mental State (MMSE) score between 12 and 20 at inclusion. The 2 primary end points were the cognitive subscale of the Alzheimers Disease Assessment Scale (ADAS-cog) and the global Clinician's Interview Based Impression of Change (CIBIC-plus).

RESULTS

After 28 weeks, the mean ADAS-cog scores were significantly improved relative to placebo. In the intention-to-treat population, the memantine group mean score had gained an average of 0.4 points, whereas the placebo group mean score had declined by 1.6 points, ie, a difference of 2.0 points (95% confidence interval, 0.49 to 3.60). The response rate for CIBIC-plus, defined as improved or stable, was 60% with memantine compared with 52% with placebo (P=0.227, intention to treat). Among the secondary efficacy parameters, which were analyzed in the per-protocol subset, MMSE was significantly improved with memantine compared with deterioration with placebo (P=0.003). The Gottfries-Brane-Steen Scale intellectual function subscore and the Nurses' Observation Scale for Geriatric Patients disturbing behavior dimension also showed differences in favor of memantine (P=0.04 and P=0.07, respectively). Memantine was well tolerated with a frequency of adverse events comparable to placebo.

CONCLUSIONS

In patients with mild to moderate vascular dementia, memantine 20 mg/d improved cognition consistently across different cognitive scales, with at least no deterioration in global functioning and behavior. It was devoid of concerning side effects.

New approaches to clinical trials in vascular dementia: memantine in small vessel disease

Although criteria for the diagnosis of vascular dementia (VaD) are established, the diagnostic concept is still controversial and there is no regulatory guidance for clinical drug development. Clinical trials in VaD present a number of pitfalls and challenges and, so far, no compound has received regulatory approval for this indication. The methodological issues of clinical VaD trials are discussed using the development of memantine for this indication as an example. In a pooled analysis of two placebo-controlled trials with the NMDA-antagonist memantine in VaD, the cognitive benefit by memantine treatment was more pronounced for patients with 'small vessel disease' than for those with other neuroradiological findings at baseline. In a subgroup of patients with 'large vessel disease' or macrolesions, there was less cognitive decline among the placebo patients. It may therefore be helpful to use predefined diagnostic subcategories in clinical studies in this indication. The findings further suggest that stroke or multiple infarctions may not be the primary reason for cognitive decline in VaD patients.

Psychodynamics and therapeutic aspects of anorexia nervosa. A study of family dynamics and prognosis

38 patients who had suffered from anorexia nervosa were examined and followed up in a catamnestic study, and their biography, family dynamics, eliciting situation and history of illness were studied. The investigation was carried out by means of interviews, questionnaires and personality tests. As to biography and family dynamics, our results are partly complementary and partly contradictory to previously published results of other investigations. Our patients received inpatient psychotherapy over an average period of 3 months and were followed up 2-5 years later. The following prognostic criteria proved to be significant: vomiting as part of the symptoms; chronification (psychotherapy delay), and ability to achieve a constructive therapist/patient alliance. Patients whose weight was largely back to normal by the end of therapy, but were still amenorrhoeic, showed unfavourable development in psychosocial relations. The catamnestic results improved with increasing time lapse between the end of therapy and follow-up investigation.