APP and Alzheimer disease: However, the exact role Abeta peptides have in AD is not clear, which is further emphasized by the failure of phase III trials of anti-Abeta therapies like the gamma-secretase inhibitor, semagacestat (Doody et al., 2013) and solanezumab, a monoclonal antibody targeting amyloid plaques (Le Couteur et al., 2016).