What We’re Learning from Alzheimer’s Research and How Biomarkers May Help
Hope and expectation have never met more frequently with disappointment in clinical trial research than for Alzheimer’s disease. But the question is, why?
The National Alzheimer’s Project Act in 20111 was enacted to “prevent or effectively treat Alzheimer’s disease by 2025,” and the chasm between research and achieving any part of the goal has never seemed greater.
The number of treatments investigated for Alzheimer’s disease that have failed is staggering. One PhRMA report2 found that between 1998 and 2014, only four of 127 medicines investigated for Alzheimer’s were approved for use.
Do we know why?
The reasons for drug trial failures in Alzheimer’s are as complex as the disease itself. Clinical trials face challenges in recruiting volunteers3, and the intricacies of the brain make it difficult for drugs to cross the blood-brain barrier.4 Furthermore, scientists are still trying to gain a full understanding of the disease biology. Biomarkers, which help health care professionals identify the presence of disease, are not currently validated for Alzheimer’s disease, although several are being researched.5
Jim Summers, Ph.D., vice president, discovery neuroscience research at AbbVie, explains, “What we know now is that the disease (Alzheimer’s) is brewing for decades before people are symptomatic, and we are trying to find ways to treat it earlier. If you have high cholesterol, for example, you don’t wait to treat it until the patient has a heart attack.”
Randall Bateman, M.D., the Charles F. and Joanne Knight Distinguished Professor of Neurology at Washington University School of Medicine, St. Louis, Missouri, and scientific co-founder of C2N Diagnostics, points to an additional cause of Alzheimer’s trial failures.
“Imagine trying to find a drug that could truly change the disease course. The odds that the drug would have benefit are greatly increased if you can demonstrate the drug does what it is designed to do. Without that information, you’re running a trial blind,” Bateman says. “If we can understand how to measure the disease process using biomarkers, the odds of (clinical trial) success are much higher.”
Biomarkers: A new approach to clinical trials
Bateman and his team at Washington University developed the stable isotope labeling kinetics (SILK™) platform to track the kinetics of two biological markers, or biomarkers6, associated with Alzheimer’s disease – tau and beta amyloid. C2N Diagnostics, co-founded by Bateman and Dr. David Holtzman, the Andrew B. and Gretchen P. Jones Professor of Neurology and head of Washington University’s Department of Neurology, has refined these SILK™ biomarkers to test a given drug’s effect on how well these proteins are produced and cleared away.
By using SILK™ technology in Alzheimer’s research, scientists can better understand how the potential biomarkers build up and are cleared from the body.
“Measuring the speed of protein changes can indicate what may happen in a drug trial. SILK™ provides a measure of the speed at which targets are affected and if the compound can normalize the abnormal protein metabolism. By measuring how much the proteins are normalized, we can then estimate the drug doses that are most likely to be successful,” Bateman explains.
Silk and pet: Two sides of the same coin
Another tool, positron emission tomography (PET), is also used in clinical trials and can help get a snapshot of biomarkers that may be stuck in the brain.
“SILK™ and PET scans are very complementary,” Bateman says. “They’re two different sides of the coin – PET scans can measure what’s stuck in the brain, while SILK™ measures what is changing. Using both gives us a complete picture.”
Partnering in Alzheimer's research
AbbVie recently joined the tau SILK™ consortium with Washington University School of Medicine and other partners. The consortium’s goal is to learn about abnormal tau build up, how tau moves through and is cleared from the brain and find ways to treat Alzheimer’s and other diseases that involve tau.
Eventually, researchers hope the findings from the studies will lead to better ways for designing clinical trials and develop new compounds to research in Alzheimer’s disease.
“The mix of academic institutions and pharmaceutical companies coming together highlights the fact that we want to work together to understand the disease and help those living with Alzheimer’s,” says Holly Soares, Ph.D., head of translational neuroscience, AbbVie.
AbbVie announced in January 2017 the start of a Phase 2 clinical trial to investigate an anti-tau antibody in early Alzheimer’s disease. To learn more about our research in neuroscience, visit our pipeline7 page.
2 PhRMA report