Focus: Blood tests needed for widespread Alzheimer's diagnosis on the way

Quanterix

11/10/2023 12:30

By Deena Beasley
       Oct 11 (Reuters) - Blood tests for Alzheimer's are
needed to more widely diagnose the brain-wasting disease and
understand its prevalence, but it will be another couple of
years before they become an everyday tool, medical experts and
company executives say.
    Blood testing is initially likely to be used to rule out
Alzheimer's, with positive results signaling the need for more
advanced diagnostics.
    Several Alzheimer's blood tests are in the works – and one
is already being sold to consumers – but none have been
established as accurate, formally approved by regulators or
reimbursed by insurers. Some are being used to help screen
participants enrolling in clinical trials of Alzheimer's
treatments. 
     Alzheimer's, which gradually destroys memory and thinking
skills, is characterized by changes in the brain including
buildup of amyloid beta plaques and tau tangles that result in
loss of neurons responsible for transmitting information.
    Currently, people who might benefit from Leqembi, the new
Alzheimer's drug from Eisai  4523.T  and Biogen  BIIB.O , need 
those changes diagnosed through cognitive assessment and a
cerebrospinal fluid (CSF) test, which requires an invasive
lumbar puncture, or an expensive PET brain scan that may not be
reimbursed by health insurers.
    Even when covered, CSF and PET testing can be hard to access
in some parts of the country. 
    Researchers have been working for years on blood tests for
Alzheimer's that can replicate these diagnostic tools. But there
is still debate over which biomarkers, or proteins in the blood,
signal the presence of amyloid and tau in the brain.
    They also say more work is needed to understand the
relationship of such biomarkers with race, underlying medical
conditions and other factors.
    The need for blood tests has become more pressing since the
FDA approved Leqembi in July. It is currently reviewing a
similar drug, donanemab, from Eli Lilly  LLY.N .
    Dr. Sarah Kremen, director of the neurobehavior program at
Cedars-Sinai Medical Center in Los Angeles, said amyloid on its
own is an unreliable marker for Alzheimer's since many people
accumulate brain deposits of the protein as they age, but do not
develop dementia.    
    Blood tests that measure the right combination of biomarkers
will eventually become the standard for diagnosing Alzheimer's,
she said, "but right now, they are not quite ready for prime
time." 
    
    NEW COMBINATION TEST ARRIVES
    Labcorp  LH.N  on Wednesday began offering to physicians a 
blood test it says measures markers for amyloid, tau and
neurodegeneration with a list price of $626.
    In July, Quest Diagnostics  DGX.N  launched the first
direct-to-consumer blood test for Alzheimer's, which costs $399
and aims to detect abnormal levels of amyloid. Data on its
accuracy has not been published.
    Cedars and other neurology centers took the unusual step of
issuing strongly-worded cautions about such consumer tests for
people who do not have risk factors or symptoms of Alzheimer's,
saying they are best used in conjunction with medical guidance.
    "The blood biomarker is a useful screening tool at first,
but additional information is needed," said Eliezer Masliah,
director of the National Institute on Aging neuroscience
division, part of the U.S. National Institutes of Health.     
    Eisai has a collaboration with C2N Diagnostics to develop
evidence supporting the use of blood-based Alzheimer's testing. 
  
    Michael Irizarry, head of clinical research at Eisai's
neurology division, said he expects the transition to
blood-based Alzheimer's diagnostics to happen over the next two
years. "Blood tests are progressing quite rapidly," he said.
    C2N, which has published and presented its data at medical
conferences, recently began offering a $1,450 updated version of
its blood test that measures amyloid and tau. 
    Eli Lilly is working with Quanterix  QRTX.O  on an
experimental tau biomarker blood test, and has partnered with
Roche  ROG.S  to develop a test measuring blood levels of a
different tau protein as well as a gene associated with
Alzheimer's risk. 
    Bruce Jordan, an executive with Roche Diagnostics, said the
company expects to have results from a large trial and file for
U.S. approval of its Elecsys Amyloid Plasma Panel in 2025.
        Accurate blood tests are expected to help identify which
dementia patients actually have Alzheimer’s, the most common but
not the only cause of dementia.
    The Alzheimer's Association estimates that 6.7 million
Americans have the disease, but acknowledges that the number
could be 30% lower if biological testing is used.
    Another analysis from RAND found that the U.S. age-adjusted
prevalence of dementia fell by a about a third to 8.5% between
2000 and 2016, possibly due to more education, less smoking and
better heart health care.
    "There is a real possibility that the field changes as real
world evidence is collected," said Russ Paulsen, chief operating
officer at patient advocacy group UsAgainstAlzheimers.
    "When there are widely available, scalable, sensitive and
specific blood tests it will be an absolute game changer for
Alzheimer's patients."       
    
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 (Reporting By Deena Beasley; editing by Caroline Humer and Bill
Berkrot)
 ((deena.beasley@thomsonreuters.com; 213 955 6746; Reuters
Messaging: deena.beasley.thomsonreuters.com@reuters.net))