The validity of biomarkers as surrogate endpoints in Alzheimer's disease by means of the Quantitative Surrogate Validation Level of Evidence Scheme (QSVLES)

A Clinician's Perspective on Biomarkers

Psychiatrists and mental health professionals regularly perform various clinical tasks (e.g., detection, differential diagnosis, prognostication, treatment selection and implementation). How well they perform each of these tasks has a direct impact on patient outcomes. Measurement-based care has brought greater precision to these tasks and has improved outcomes. This article provides an overview of the types of biomeasures and biomarkers, the clinical uses of biomarkers, and the challenges in their development and clinical use. Although still in their infancy, biomarkers hold the promise of bringing even greater precision and even better outcomes in mental health. Biomeasures that could become biomarkers include genetic, proteomic, metabolomic, and immunologic measures, as well as physiological, functional, and brain structural measures. Mechanistic markers reflect and are based on the specific pathobiological processes that are involved in the development of a clinically defined condition. Some clinically relevant biomarkers may rely on this mechanistic understanding while others may not. Clinical biomarkers serve three broadly defined goals. Diagnostic markers define what is wrong. Prognostic markers define what will happen in the natural course of the condition, although they may also predict the course of illness during treatment. Theranostic markers address issues pertinent to treatment by defining whether, when, whom, and how to treat. Other biomarkers may be used to monitor the overall effect of treatment regardless of the therapeutic effects or to monitor the specific therapeutic effects of the intervention on the disorder itself. Biomarkers can also be used to estimate susceptibility/risk of developing the condition or the biological consequences of having had the disorder.

Biomarkers for Alzheimer's disease therapeutic trials

The development of disease-modifying treatments for Alzheimer's disease requires innovative trials with large numbers of subjects and long observation periods. The use of blood, cerebrospinal fluid or neuroimaging biomarkers is critical for the demonstration of disease-modifying therapy effects on the brain. Suitable biomarkers are those which reflect the progression of AD related molecular mechanisms and neuropathology, including amyloidogenic processing and aggregation, hyperphosphorylation, accumulation of tau and neurofibrillary tangles, progressive functional, metabolic and structural decline, leading to neurodegeneration, loss of brain tissue and cognitive symptoms. Biomarkers should be used throughout clinical trial phases I-III of AD drug development. They can be used to enhance inclusion and exclusion criteria, or as baseline predictors to increase the statistical power of trials. Validated and qualified biomarkers may be used as outcome measures to detect treatment effects in pivotal clinical trials. Finally, biomarkers can be used to identify adverse effects. Questions regarding which biomarkers should be used in clinical trials, and how, are currently far from resolved. The Oxford Task Force continues and expands the work of our previous international expert task forces on disease-modifying trials and on endpoints for Alzheimer's disease clinical trials. The aim of this initiative was to bring together a selected number of key international opinion leaders and experts from academia, regulatory agencies and industry to condense the current knowledge and state of the art regarding the best use of biological markers in Alzheimer's disease therapy trials and to propose practical recommendations for the planning of future AD trials.

IAGG workshop: health promotion program on prevention of late onset dementia

IAGG, WHO, and SFGG organized a international workshop on Health promotion programs on prevention of late on-set dementia. Thirty world specialists coming from Europe, North America, Asia, South America, Africa and Australia, shared their experience on methods and results of large epidemiological interventions to reduce incidents of dementia or delay its on-set. Chaired by Laura FRATIGLIONI, an expert in Epidemiological studies on dementia issues, the workshop gave opportunity for discussions and controversies about the state-of-the-art. Based on different national and international trials (ADAPT, MAPT, FINGER, GUDIAGE, GEM etc) the questions remained opened for different aspects of methodology, the choice of domain or multi domain intervention, the choice and the definition of the target populations, the best age of candidates, the issues related to the discrepancy between late effects, and interventions' duration. We are please to publish in the Journal, the presentations presented to this workshop. These publications will complete previously task force published in the journal in the last two years on methodological issues for Alzheimer's trials including end point, biomarkers, and the experience of past therapeutic trials.

[The Alzheimer's disease: how to estimate the impact of the pathology and the treatment?]

The Alzheimer's disease (AD) is a neuro-degenerative pathology which establishes at present the most frequent cause of dementia. The therapeutic which we have actually are symptomatic treatments which do not modify the evolution of the disease. A clinical and cognitive evaluation is sufficient mostly to estimate the efficiency of these symptomatic treatments. The development of treatments to modify the natural evolution of AD (disease modifying) requires the implementation of innovative therapeutic tries with a significant number of subjects, a long period of observation and where the only clinical criteria of evaluation seem insufficient. The use of biomarkers of plasma, cerebrospinal fluid, or neuro-imaging could play an important role to estimate their efficiency. However, at present no biomarker is validated as surrogate endpoint. It seems today indispensable to use them in the therapeutic tries so as to validate and standardize their methods of acquisition, measure and analysis.

What is a biomarker? Research investments and lack of clinical integration necessitate a review of biomarker terminology and validation schema

A continual trend of annual growth can be seen within research devoted to the discovery and validation of disease biomarkers within both the natural and clinical sciences. This expansion of intellectual endeavours was quantified through database searches of (a) research grant awards provided by the various branches of the National Institutes of Health (NIH) and (b) academic publications. A search of awards presented between 1986 and 2009 revealed a total of 28,856 grants awarded by the NIH containing the term "biomarker". The total funds for these awards in 2008 and 2009 alone were over $2.5 billion. During the same respective time frames, searches of "biomarker" and either "discovery", "genomics", "proteomics" or "metabolomics" yielded a total of 4,928 NIH grants whose combined funding exceeded $1.2 billion. The derived trend in NIH awards paralleled the annual expansion in "biomarker" literature. A PubMed search for the term, between 1990 and 2009, revealed a total of 441,510 published articles, with 38,457 published in 2008. These enormous investments and academic outputs however have not translated into the expected integration of new biomarkers for patient care. For example no proteomics derived biomarkers are currently being utilized in routine clinical management. This translational chasm necessitates a review of the previously proposed biomarker definitions and evaluation schema. A subsequent discussion of both the analytical and pre-analytical considerations for such research is also presented within. This required knowledge should aid scientists in their pursuit and validation of new biological markers of disease.