Expert opinion on drug discovery
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Expert Opin Drug Discov · Jan 2012
ReviewAdvances in the identification of γ-secretase inhibitors for the treatment of Alzheimer's disease.
In an attempt of altering the natural history of Alzheimer's disease (AD), several compounds have been developed with the aim of inhibiting γ-secretase, the enzymatic complex generating β-amyloid (Aβ) peptides (Aβ(1 - 40) and Aβ(1 - 42)), from amyloid precursor protein (APP). APP is believed to be involved in the pathophysiological cascade of AD. ⋯ Studies in both transgenic and non-transgenic animal models of AD have indicated that γ-secretase inhibitors, administered by the oral route, are able to lower brain Aβ concentrations. However, scanty data are available on the effects of these compounds on brain Aβ deposition after prolonged administration. γ-Secretase inhibitors may cause significant toxicity in experimental animals and in humans believed to be associated with the inhibition of the cleavage of Notch, a transmembrane receptor involved in regulating cell-fate decisions. Unfortunately, two large Phase III clinical trials of semagacestat in mild-to-moderate AD patients were prematurely interrupted because of the observation of a detrimental cognitive and functional effects of the drug, possibly due to its lack of selectivity on APP processing. New APP-selective γ-secretase inhibitors are being developed with the hope of overcoming the previous setbacks.