The secretases: enzymes with therapeutic potential in Alzheimer disease

Abstract

The three secretases that process amyloid precursor protein are central to the generation of amyloid-β, and the accumulation of this peptide in extracellular plaques is one of the hallmarks of Alzheimer disease. In this Review, De Strooper et al. discuss the evidence that suggests that these enzymes are potential therapeutic targets for Alzheimer disease drug treatments. The amyloid hypothesis has yielded a series of well-validated candidate drug targets with potential for the treatment of Alzheimer disease (AD). Three proteases that are involved in the processing of amyloid precursor protein—α-secretase, β-secretase and γ-secretase—are of particular interest as they are central to the generation and modulation of amyloid-β peptide and can be targeted by small compounds in vitro and in vivo. Given that these proteases also fulfill other important biological roles, inhibiting their activity will clearly be inherently associated with mechanism-based toxicity. Carefully determining a suitable therapeutic window and optimizing the selectivity of the drug treatments towards amyloid precursor protein processing might be ways of overcoming this potential complication. Secretase inhibitors are likely to be the first small-molecule therapies aimed at AD modification that will be fully tested in the clinic. Success or failure of these first-generation AD therapies will have enormous consequences for further drug development efforts for AD and possibly other neurodegenerative conditions.