trialsitenews Staff at TrialSite | Quality Journalism
Apr. 12, 2024, 1:00 p.m.
Expensive and not always covered by insurance, the standard most reliable method of diagnosing Alzheimer’s disease is via positron emission tomography or PET scan of the brain. Another more cumbersome, invasive and painful approach is the spinal tap. What if there was an easier, more economical way to diagnose via a blood test? That’s exactly the goal of the Bio-Hermes study, sponsored by the Global Alzheimer’s Platform Foundation. Among the trial sites involved is Axiom Brain Health in Tampa. The successful completion of the substantial study has led to the launch of LabCorp’s 217 Alzheimer’s blood test. The product will most likely be used in clinical trials and by physicians.
The Study
Listed in the national U.S. clinical trials registry, the Bio-Hermes study (NCT04733989) was designed to develop a blood, digital, and brain amyloid PET scan biomarker database that can be used to determine whether a meaningful relationship exists between digital tests, blood amyloid-beta, p-tau, and neurofilament biomarker levels and amyloid-beta levels identified through brain amyloid PET images. Blood collected is genetically sequenced to gain insights about genes and brain amyloid. The Bio-Hermes study will involve about 1,000 volunteers over the age of 60 screened for Preclinical Alzheimer’s Disease, Prodromal AD, or Mild Dementia AD, and includes an endpoint enrollment requirement of 200 participants from underrepresented minority populations.
Axiom Brain Health has been one of several Florida trial sites, a popular location to recruit for dementia-related studies given the retirement population in the state.
Recently covered by the Tampa Bay Times, the novel test needs to detect amyloid presence in the brain. The protein which clumps together is considered a biomarker for the neurodegenerative disease that can rob humans of the most cherished asset—our memory.
Study Results
As reported by the Global Alzheimer’s Platform Foundation, results from blood-based biomarker tests correlated with the presence of beta-amyloid detected using established Alzheimer’s disease diagnostics. Those results were published in February, in the journal Alzheimer’s & Dementia.
PET scans and cerebrospinal fluid (CSF) analyses are highly accurate and established methods of identifying elevated levels of beta-amyloid, a hallmark of Alzheimer’s. However, these modalities have their drawbacks. For example, PET scans are expensive, and not all patients have access to healthcare facilities with the requisite equipment and specialists on staff. CSF analysis requires a lumbar puncture, which patients may consider invasive and be hesitant to receive.
Blood tests for specific protein biomarkers may have the near-term potential of prescreening individuals suspected of having Alzheimer’s before they undergo a confirmatory PET scan or CSF analysis, particularly in the context of clinical trials.
The hope is that one day these blood tests could be standalone diagnostics for identifying which patients have Alzheimer’s and can receive anti-amyloid drugs like Biogen and Eisai’s Leqembi (lecanemab), which require patients to have a confirmed presence of amyloid pathology.
Identifying blood-based biomarkers for beta-amyloid has been a key area of interest in the life sciences industry, as the increasingly crowded market for anti-amyloid-targeted drugs is expected to drive demand for beta-amyloid testing.
The latest publication contains the first key analysis from the Bio-Hermes study, which the GAP Foundation and a consortium of about 20 biopharmaceutical, diagnostic, and nonprofit partners launched to research new biomarkers for diagnosing Alzheimer’s. The study comprises data from more than 1,000 people in the US with mild Alzheimer’s, mild cognitive impairment, and healthy cognition.
The analysis was funded by AbbVie, the Alzheimer’s Drug Discovery Foundation, Aural Analytics, Biogen, Cognivue, C2N, Gates Ventures, Linus Health, Merck, Quanterix, Retispec, and Roche.
In this study, researchers compared results of multiple blood-based biomarker tests to either results from brain PET scans with Eli Lilly’s Amyvid (florbetapir F-18) radiotracer or cerebrospinal fluid (CSF) assays that were sent to a CLIA-certified lab at Quest Diagnostics for analysis. The biomarkers from blood tests were also gauged at CLIA-certified labs operated by C2N Diagnostics, Quanterix, and Eli Lilly.
The study authors found a strong correlation between results from several blood tests and the presence of beta-amyloid plaque as determined by the standard testing methods.
In particular, blood tests for amyloid-beta 42/40 ratio, phosphorylated-tau 181, and phosphorylated-tau 217 predicted the likelihood that a patient would have beta-amyloid plaque in their brain as detected by conventional diagnostics. P-tau 217 had the strongest predictive value for amyloid-beta positivity, reaffirming other research that has identified it as a promising blood-based biomarker, and which some experts say may eventually be used as a standalone confirmatory test for brain amyloid positivity.
While p-tau 217 has emerging evidence that makes it one of the most promising blood-based biomarkers of brain amyloid positivity, researchers are still trying to better understand why this biomarker has such a correlation, according to Richard Mohs, CSO Global Alzheimer’s Platform. One hypothesis is that the accumulation of beta-amyloid protein in the brain leads to abnormal formation and build-up of the tau protein.
The authors wrote in their study:
“We don’t fully understand why p-tau 217 is so good at predicting brain amyloid deposits,” he said. “It seems likely that the overproduction of some forms of a-beta protein causes the production of p-tau 217, so any patient beginning to show a-beta deposits into amyloid will have elevated levels of p-tau 217.”
There was no significant relationship between amyloid-beta positivity and other biomarkers researchers studied, such as amyloid-beta 40 and total tau.
In light of their findings, the study authors suggested that blood tests, which are more convenient and less expensive than existing diagnostics, could be useful as a prescreening method before PET scans or CSF analysis to identify those likely to have elevated beta-amyloid. Such prescreening could help avoid costly or invasive procedures for patients who don’t have beta-amyloid deposits.
This is already being done within some clinical trials. For example, in Eisai’s AHEAD study, in which the drugmaker is investigating whether Leqembi can delay or prevent cognitive decline in those who are asymptomatic but have elevated levels of beta-amyloid, patients are first screened with C2N’s PrecivityAD blood-based test. Positive results are then confirmed with an amyloid PET scan.
In the Alzheimer’s & Dementia paper, study authors highlighted that their findings on the blood biomarkers were consistent across racial and ethnic groups, although the average values for amyloid-beta 42/40 ratio were slightly higher and p-tau 181 and p-tau 217 concentrations were lower in Black patients compared to their white counterparts. “Results indicate that A?42/A?40 ratio, p-tau181, and p-tau217 are good predictors of brain amyloid positivity in this clinical trial-ready population and suggest that further separate evaluation of biomarkers for Hispanic or non-Hispanic Black participants may be useful,” study authors wrote.
Recruiting diverse participants has been a focus for the Bio-Hermes study, since Black and Latino patients tend to suffer from Alzheimer’s at higher rates than white patients, study authors noted. Nearly one-quarter of the study population in Bio-Hermes was from historically underrepresented racial or ethnic groups.
Richard Mohs, CSO of Global Alzheimer’s Platform noted that the initial adoption of these blood tests will likely be in the clinical trial space, however, envisions a time in the “near future” when patients will be able to prove evidence of amyloid pathology with only a blood-based biomarker test, without needing a PET scan or CSF analysis. “While the near-term use of these tests is likely to be for enrollment into clinical trials, the blood-based tests, particularly p-tau 217, are likely to be very useful in clinical practice.”
Blood Test Product Launch
The sponsor of Bio-Hermes reported last month that as a result of the published results of the Bio-Hermes-001 study LabCorp announced its launch of new blood tests to detect the brain protein called tau. The Bio-Hermes study reveals a strong correlation between p-tau 217 with the presence of amyloid plaques in the brain, a diagnostic hallmark of Alzheimer’s disease.
John Dwyer, President of the Global Alzheimer’s Platform Foundation is encouraged by this announcement:
“Today, we are encouraged by Labcorp’s launch of a p-tau 217 Alzheimer’s blood test, as there is a pressing need to diagnose Alzheimer’s disease more quickly and efficiently. As we demonstrated in the published results from GAP’s Bio-Hermes study, the p-tau 217 blood marker test represents a promising pathway for providing critical information to physicians and patients about the underlying pathology that may be affecting a patient’s cognition. We applaud Labcorp for accelerating the introduction of new Alzheimer’s tests as we are convinced there will be a surge of patients asking their doctors if new disease modifying Alsheimer’s therapies are right for them. Blood markers like p-tau 217 are solutions that can make this process faster and more reliable than ever before.”
The Blood Test
Developed by LabCorp, the 217 Alzheimer’s blood test is used to aid in the biological identification of Alzheimer’s disease by measuring phosphorylated tau 217, which has been shown in the literature to be a surrogate of amyloid pathology. Additionally, pTau-217 can be used for monitoring patients on newly approved anti-amyloid therapy.
The Florida Trial Site
Axiom Brain Health touts on its website that the trial site performs clinical research that provides exceptional patient care and efficiently produces high quality, clean and credible research data. Located in Tampa, Florida, the trial site focuses on successful completion of Phase II – IV neurology clinical studies in an outpatient setting since 1993.