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Payor Coverage a Looming Challenge for Alzheimer's Blood Tests

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NEW YORK – While blood-based tests for Alzheimer's disease have made rapid advances lately, payor coverage for these tests remains rare.

This is largely a function of the tests' novelty, as blood-based assays have only recently come to market and none have yet received US Food and Drug Administration approval. Yet, while it is still early days for blood-based Alzheimer's testing, industry and clinicians should begin laying the groundwork for coverage of these tests, researchers from the University of California, San Francisco (UCSF), argue in a recent commentary published in the Journal of the American Medical Association.

Recent high-profile scientific publications have driven increased discussion of Alzheimer's blood tests both within the medical community and more generally, said Kathryn Phillips, a professor of health economics and health services research at UCSF and an author on the JAMA article. Much work still needs to be done, however, to address questions of whether payors will cover such tests and for what purposes and in which patients, she said.

Blood-based testing for Alzheimer's has drawn strong interest as many see it as a potential alternative to existing diagnostic tools like cerebrospinal fluid-based testing and PET imaging, which are more invasive and/or expensive. Several studies have shown that blood tests can achieve greater than 90 percent accuracy compared to CSF testing and PET for detecting the brain amyloid pathology characteristic of Alzheimer's in symptomatic individuals.

Quest Diagnostics, Laboratory Corporation of America, C2N Diagnostics, and Quanterix have blood-based Alzheimer's laboratory-developed tests (LDTs) on the market, while companies including Roche and Beckman Coulter Diagnostics have blood tests in development. Last month Fujirebio Diagnostics said it filed its Lumipulse G pTau 217/β-Amyloid 1-42 Plasma Ratio in vitro diagnostic test with the FDA for potential regulatory approval.

Asked about his company's progress on the coverage front, Quanterix CEO Masoud Toloue said in an email that "while progress has been made with approving new codes, pricing and coverage need to be established to support broad access to testing. Quanterix is engaged with payors, and is generating the necessary evidence to support the clinical utility of our tests. This work is ongoing."

Quest spokesperson Jennifer Petrella likewise said the company's work on payor coverage is "ongoing," noting that the company "is committed to working with health plans to support coverage of our broad menu of Alzheimer’s disease tests." She pointed to a Quest-led study published this year in Frontiers in Neurology that indicated the company's Alzheimer's blood test could help rule out individuals as being unlikely to have amyloid brain pathology and thereby reduce the need for PET imaging.

Exactly how blood-based testing will best fit into clinical pathways is still being worked out, Phillips and her coauthors noted. They cited as possible uses qualifying individuals for treatment with anti-amyloid drugs like Eisai's Alzheimer's drug Leqembi (lecanemab) and Eli Lilly's drug Kisunla (donanemab); triaging symptomatic patients to determine if additional workups via CSF testing or PET is needed; and screening asymptomatic individuals to assess their risk of developing symptomatic disease.

"The evidence base for these use cases is variable," they wrote, "with some marketed [tests] having robust validation data for specific use cases but not others."

Among the key questions for payors are "who should you offer the testing to, to begin with, and can you really limit it to the appropriate population," Phillips said. She noted that vendors' past and ongoing marketing of Alzheimer's blood tests to asymptomatic individuals — in whom the tests' performance is less well supported — highlight the challenge of limiting testing to appropriate patients.

For instance, Quest initially made its consumer-initiated AD-Detect Alzheimer's blood test available to asymptomatic individuals, though the company backtracked following criticism of that decision. Meanwhile, Apollo Health explicitly markets its Brainscan Alzheimer's blood test (which is performed by Bellingham, Washington-based clinical lab Neurocode Labs) to asymptomatic individuals, advertising on its website that it can "detect cognitive decline before symptoms start."

"What we're seeing in the blood biomarker field is a need to get closer to a consensus on the types of tests and the types of results that should be expected from these tests," said Rebecca Edelmayer, VP of scientific engagement for the Alzheimer's Association. "There is still a lot of work that needs to be done in terms of standardization and validation of these tests."

She noted that even in the relatively more established CSF Alzheimer's testing space, payor coverage has been variable. Coverage has also been a challenge for PET imaging. Until last year, CMS only covered amyloid PET imaging for individuals participating in clinical trials. In October 2023, the agency moved to allow its Medicare administrative contractors (MACs) to develop their own coverage policies for the test.

Edelmayer noted that updated guidelines from an Alzheimer's Association working group incorporate blood testing for the first time as part of the diagnosing and staging of Alzheimer's disease. The guidelines establish a set of core biomarkers, including plasma-based amyloid-β(Aβ)42; plasma phosphorylated tau (p-tau) 217, 181, and 231; and plasma microtubule-binding region (MTBR)-tau 243. They also set out intended uses for these markers, establishing plasma p-tau 217 and plasma p-tau 217 ratio as tools for diagnosing, staging, and determining the prognosis of Alzheimer's, as well as assessing the effect of treatment.

However, "there is not yet really detailed guidance on how to use blood tests in the field," she said.

The Alzheimer's Association is seeking to fill this gap by "leading the development of a formal clinical practice guideline for blood biomarkers in Alzheimer's disease … to help clinicians in their decision-making on whether or not a blood biomarker test … is appropriate for their patients and in which clinical settings they should be used," Edelmayer said.

She said the working group developing the guideline is exploring questions including whether such tests should be used only by specialists or also in primary care; whether they should be used in individuals with cognitive impairment or in individuals who are cognitively normal; and whether they should be used to triage additional testing or as confirmatory testing.

She noted that existing data on blood-based Alzheimer's testing has almost entirely been generated in settings where clinicians experienced in diagnosing and treating memory disorders are using the tests as an aid in evaluating individuals with cognitive symptoms.

Edelmayer added that while the working group will be evaluating how well blood biomarkers correspond to brain amyloid status as determined by CSF or PET testing, it won't be making recommendations as to whether blood tests can be used alone — in the absence of additional clinical factors and judgment — to determine whether an individual should be given an anti-amyloid treatment.

"That is a question the panel may address in the future when more evidence has been published around that concept," she said. "But today such little evidence exists that we can't even evaluate it."

Edelmayer said the organization aims to submit the guideline in early 2025, adding that it will "help create a framework for payor decision-making."