'Clinical trials in Alzheimer's disease': immunotherapy approaches.

Recent advances in the understanding of Alzheimer's disease pathogenesis have led to the development of numerous compounds that might modify the disease process. Amyloid β (Aβ) peptide represents an important molecular target for intervention in Alzheimer's disease. Several types of Aβ peptide immunotherapy for Alzheimer's disease are under investigation, direct immunization with synthetic intact Aβ(42) , active immunization involving the administration of synthetic fragments of Aβ peptide conjugated to a carrier protein and passive administration with monoclonal antibodies directed against Aβ peptide. Pre-clinical studies showed that immunization against Aβ peptide can provide protection and reversal of the pathology of Alzheimer's disease in animal models. Indeed, several adverse events have been described like meningoencephalitis with AN1792, vasogenic edema and microhemorrhages with bapineuzumab. Although immunotherapy approaches resulted in clearance of amyloid plaques in patients with Alzheimer's disease, this clearance did not show significant cognitive effect for the moment. Currently, several Aβ peptide immunotherapy approaches are under investigation but also against tau pathology.