Immunotherapy against amyloid pathology in Alzheimer's disease

The first drugs developed for Alzheimer's disease (AD), anticholinesterase inhibitors (AchEI), increase acetylcholine levels, previously demonstrated to be reduced in AD. To date, four AchEI are approved for the treatment of mild to moderate AD. A further therapeutic option available for moderate to severe AD is memantine. These treatments are symptomatic, whereas drugs under development are supposed to modify pathological steps leading to AD, thus acting on the evolution of the disease. For this reason they are currently termed "disease modifying" drugs. To block the progression of the disease, they have to interfere with pathogenic steps at the basis of clinical symptoms, including the deposition of extracellular amyloid beta (Aβ) plaques and of intracellular neurofibrillary tangles. The most innovative approach is represented by the vaccination and passive immunization against Aβ peptide. In this article, current knowledge about concluded and ongoing clinical trials with both vaccination with different antigens and passive immunization will be reviewed and discussed.