Barriers to Alzheimer disease drug discovery and development in the biotechnology industry

Toward the validation of functional neuroimaging as a potential biomarker for Alzheimer's disease: implications for drug development

Despite investments carried out in the research since Alzheimer's disease (AD) was firstly defined as an isolated clinical entity, there is still a lack of appropriate cure and effective therapies to halt or slow the disease progression. While fundamental research has provided a better characterization of AD, much remains to be done for the development of new biological treatment strategies. It is now being debated whether functional neuroimaging (FNI) could help improve diagnostic accuracy and become a possible biomarker of AD. The primary purpose of this review was to determine whether data already published in the literature meet formal technology assessment standards for using regional cerebral blood flow (rCBF) or glucose metabolism (rCMRGlu) as a biomarker for AD. The secondary purpose was to identify any remaining gaps that might need to be systematically addressed before drug developers and regulators accept FNI as a biomarker for AD. The present paper reviews the literature regarding metabolic positron emission tomography (PET) and perfusion single photon emission computed tomography (SPECT) studies in AD. There is evidence that treatment with acetylcholinesterase inhibitors (AChEI) leads to changes in brain physiology within the brain regions critical to AD pathology, i.e. the temporal, parietal and frontal association cortex. However, a thorough analysis combining functional and neuropsychological data has not yet been attempted, and much research is needed to validate the role of FNI as a surrogate endpoint for AD clinical trials.

Study Design in Dementia Drug Trials

A great deal of progress has been made in the management of Alzheimer's disease and other dementias over the past 25 years. Much remains to be achieved, however. This article discusses some of the issues surrounding study design. In the absence of an accepted biological marker of progression, it is unlikely that a novel study design, such as randomized start or withdrawal, in itself could provide convincing evidence of disease modification. Biological markers will also be crucial in the development of therapies aimed at specific processes, and of immunotherapies.