Background:

Begacestat (GSI-953) is a selective thiophene sulfonamide inhibitor of amyloid precursor protein gamma-secretase (IC50Aβ40=15 nM) for the treatment of Alzheimer's disease[1].

Begacestat (5 mg/kg, p.o. in mice) treatment for 4 h significantly reduces the Aβ40 and Aβ42 in brain (37% lowering of brain Aβ40 and 25% lowering of Aβ40 observed)[1].Begacestat (GSI-953: 0, 2.5, 5, or 10 mg/kg, oral gavage, 3 h) results in a dose-dependent reversal of contextual fear conditioning deficits when compound is orally administered 3 h before training. Significant deficits are observed after treatment with 2.5 mg/kg Begacestat, and there is some reversal of this at 5 mg/kg and full reversal at 10 mg/kg compared with vehicle-dosed Tg2576 mice[2].A dosage-related trend of slightly lower percentages of SP CD4+ cells in males at all dosages (SP CD4+ cells=