Upcoming therapy?
Having a test that verifies Alzheimer’s disease is becoming all the more important now that a therapy might soon be available. Massachusetts-based biotech company Biogen has submitted aducanumab, a monoclonal antibody that targets amyloid-beta (Abeta), to the Food and Drug Administration for approval. Should that move forward, aducanumab would be the first disease-modifying therapy for Alzheimer’s disease.
“If that’s the case, it will be even more important to have simple ways to screen people, to see if they might eventually be eligible for treatment,” said Dr. Boxer. Even if the drug isn’t approved, many patients simply want to know what is causing their cognitive problems, he added. Knowing they have Alzheimer’s disease might impact their life planning. If they have mild symptoms, interventions such as exercise and reducing cardiovascular risk could improve their overall health and quality of life, he said.
If individuals have another type of dementia, such as FTLD, that, too, might determine a different approach. Some forms of FTLD are caused by “completely different biological processes,” which are now being studied, Dr. Boxer said. So knowing that patients have this condition would allow them to participate in relevant clinical trials.
Exciting aspect
Having a tau blood test will also help those in underserviced and minority communities who can’t easily access memory specialists, Dr. Boxer noted. “It might allow them to access care, and get help much more easily, and that is a really exciting aspect of this new technology,” he said. It’s not clear when such blood tests will be on the market, although many companies are “scrambling” to make them available, said Dr. Boxer.
P-tau217 also holds promise as a marker for early Alzheimer’s disease pathology, according to another study presented at AAIC 2020. A Swedish research team measured P-tau217 in more than 1,000 participants, including those who were unimpaired and those with mild cognitive impairment, Alzheimer’s disease dementia, or non-Alzheimer’s disease neurodegenerative diseases.
Results showed that plasma P-tau217 levels increase in early stages of Alzheimer’s disease when insoluble tau aggregates are not yet detectable with PET. They also predict subsequent increases in tau-PET, as well as conversion to Alzheimer’s disease dementia.
‘Incredible breakthrough’
Commenting on the research, Howard Fillit, MD, founding executive director and chief science officer of the Alzheimer’s Drug Discovery Foundation, called the study amazing and “an incredible breakthrough.
“Researchers are able to detect disease up to 20 years before symptoms. The blood test has very good characteristics in terms of sensitivity and specificity. It correlates with the spinal fluid, it’s better than the PET imaging, it correlates with the amyloid test, and the results are being confirmed in many different cohorts,” said Dr. Fillit, who was not involved with the research.
A tau blood test, especially for P-tau 217, has the potential to be as important to determining dementia risk as cholesterol is to gauging heart disease risk, he added.
Having a tau blood test will “make our clinical trials much more precise and more efficient and reduce costs tremendously,” Dr. Fillit said, adding that he thinks tau blood tests might come to market as early as within a year.
Also commenting on the research, Rebecca M. Edelmayer, PhD, director of scientific engagement for the Alzheimer’s Association, said the new studies illustrate the rapid progress being made “in the blood biomarker space.”
Even 5 years ago, researchers would “never have thought” that blood biomarkers could be used as a tool to detect brain changes related to Alzheimer’s disease, said Dr. Edelmayer.
These new studies are “filling a gap in our understanding around tau” in Alzheimer’s disease and other neurodegenerative diseases, she said. “Being able to distinguish between diseases is going to be very, very crucial for clinicians in the future,” she added.
Dr. Edelmayer foresees that in the future there will be a panel of blood biomarkers in addition to imaging tests to help clinicians make an accurate diagnosis.
The study was supported by the National Institutes of Health and the Tau Research Consortium. Dr. Boxer disclosed that the blood p-tau test was done as part of a research collaboration between UCSF and Eli Lilly. Dr. Fillit and Dr. Edelmayer have disclosed no relevant financial relationships.
A version of this article originally appeared on Medscape.com.