Patching up Alzheimer's safely
Alzheimers disease which has been shown to clear brain-damaging
amyloid plaques in preclinical studies, offering hope to millions
of sufferers worldwide.
The researchers at the University of South Florida (USF) suggest that the patch-based delivery approach will not be associated with toxicities that have caused problems with other injectable vaccines for Alzheimer's.
The group claims it is the first to show that a transdermal vaccine,which triggers the immune system to clear amyloid beta - a protein found in abnormal quantities in brains of Alzheimer's patients - can be effective and safe.
"Specialised immune cells prevalent in the skin, called Langerhans cells, may direct the body's reaction to the vaccine toward a response that is beneficial instead of overly aggressive and ultimately harmful," said Jun Tan, USF.
A number of AD vaccines have been developed in the past few years but they are still in development, with acetylcholinesterase inhibitors (AchI) currently dominating the market despite limited efficacy. The global Alzheimer's disease therapeutics market is predicted to grow 11 per cent each year to reach $3.05bn in 2009.
A vaccine for Alzheimer's disease developed by Elan and Wyeth that used modified beta amyloid as an antigen entered clinical trials in 2002, but testing had to be stopped abruptly after some patients developed brain inflammation. The two companies pressed on and in 2005 started an 18-month Phase II trial of another Alzheimer's drug candidate - a monoclonal antibody-based immunotherapeutic called bapineuzumab.
Meanwhile, ID Biomedical, recently acquired by UK-headquartered drug major GlaxoSmithKline, has been developing a vaccine for Alzheimer's that combines its novel adjuvant Protollin with glatiramer acetate, the active ingredient in Teva's multiple sclerosis drug Copaxone.
And researchers at Tokyo Metropolitan University recently suggested that DNA vaccines could provide a cheap and effective strategy for treating Alzheimer's in future. Their findings support the idea that a vaccine is the best hope for fighting this disease for which there is currently no cure.
The global Alzheimer's drug market has been dominated by Pfizer's Aricept (donepezil), which holds over 50 per cent of the global market. Novartis's Exelon (rivastigmine), Ortho-McNeil's Razadyne/Reminyl (galantamine) and Forest Laboratories' Namenda (memantine) share the remainder.
Future USF research plans include testing whether the transdermal vaccine also affects memory loss often associated with Alzheimer's patients.
The researchers have described their results in a recent article in Proceedings of the National Academy of Sciences.