With roughly 1 in 10 Americans over 65 living with Alzheimer's disease, any progress in the effort to fight the disease would be a welcome advancement for millions of people. Experts at Mayo Clinic are cautiously optimistic that a new antibody known as BAN2401 will continue to show an ability to delay progression of Alzheimer's reducing amyloid accumulation in the brain as it has during early-phase clinical trials.
"It's the most costly disease to our society right now," says Dr. Ronald Petersen, director of the Mayo Clinic Alzheimer's Disease Research Center. "It exceeds cancer. It exceeds heart disease with regards to costs to society."
That's why Dr. Petersen is hopeful BAN2401 will live up to its early promise after so many other attempts at effective Alzheimer's treatments have failed.
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There is no cure for Alzheimer's, and all currently available drugs can do is treat symptoms. But BAN2401's purpose is to slow the progression of the disease.
Dr. Petersen says BAN2401's approach to Alzheimer's treatment is based on the amyloid hypothesis.
"Alzheimer's disease is biologically defined as the presence of plaques and tangles in the brain," Dr. Petersen says. "The plaques are made of the protein called 'amyloid,' and the tangles are made of the protein called 'tau.' So if that's Alzheimer's disease, then the amyloid hypothesis implies that amyloid, the one protein, gets laid down in the brain – meaning it gets misprocessed in the brain – and forms this sticky clump of toxic material."
"The hypothesis contends that, once the amyloid is misprocessed – laid down in the brain – it begins a sequence of events, like the subsequent misprocessing of the tau protein, which causes the tangles. That leads to the death of nerve cells, and, eventually, clinical symptoms arise from that sequence of events," Dr. Petersen says.
He says people usually won't show symptoms of Alzheimer's for 10 to 20 years after the initiating event of the amyloid misprocessing.
Dr. Petersen explains that BAN2401, an antibody against the amyloid protein, is believed to be capable of removing some amyloid protein from the brain.
During the clinical trial, patients who had mild cognitive impairment or very mild dementia underwent positron emission tomography scans to confirm the presence of the amyloid protein in the brain. They were then given the antibody in one of five possible doses, or a placebo.
"They followed the people for up to 18 months, and those individuals who received the highest dose of the drug actually had less amyloid in the brain at 18 months than they had at the beginning of the trial," Dr. Petersen says. "And they were clinically stable, or they declined only a little bit, compared to the placebo participants who did not have any [significant] reduction in the amyloid amount in the brain. And [those who received the placebo] declined more rapidly than the people who got the [highest] dose of the drug."
Even though it was an early, phase 2 trial, the results suggest the drug may remove one of the toxic proteins from the brain that causes Alzheimer's disease. If the results continue to hold up through continued testing and trials, it may eventually be possible to offer BAN2401 to people in whom amyloid protein is detected to prevent or delay the symptoms of Alzheimer's disease from developing.
Dr. Petersen says it was a complicated trial design, but he remains cautiously optimistic about the results.
"It gives us a shot in the arm because there have been so many failures of major drug trials in the Alzheimer's field in the last 10 years that, when we see a positive signal like this moving in the right direction clinically and biologically, it's encouraging," Dr. Petersen says.
"With the enormous impact of Alzheimer's disease on society, on the health care economy, if we can make progress with regard to treatments that may reduce the number of people with the disease, delay the onset, slow the progression of the disease, that would be huge for individuals, families and the health care systems."
But Dr. Petersen warns a potential breakthrough that benefits patients and their families still could be a long way off.
In the meantime, in addition to drug interventions to treat symptoms of Alzheimer's, he says people can make lifestyle modifications to lower their risk of the disease.
"There is a fair amount of evidence that exercise, aerobic exercise – maybe some resistance training, as well – can actually slow the progression or delay the onset of clinical symptoms," Dr. Petersen says. "We recommend that people stay intellectually active, stay involved in their social networks. And from a dietary perspective ... perhaps a heart-healthy diet, a Mediterranean diet, may be useful again in delaying the onset and slowing the progression of the disease."
Dr. Ronald Petersen has previously consulted for Biogen Inc., the maker of BAN2401, but not on this study.