A First: FDA Approves Alzheimer’s Blood Test

In a milestone for Alzheimer’s disease diagnosis and care, the U.S. Food and Drug Administration on May 16 cleared for marketing the first AD blood test. Fujirebio’s Lumipulse G p-tau217/Aβ42 immunoassay should be used to aid diagnosis in cognitively impaired people 55 years old and up, the agency said. It is not intended as a stand-alone diagnostic. Separately, a bipartisan bill to encourage primary care doctors to assess Medicare patients for cognitive impairment was re-introduced to Congress today.

Three years ago, the FDA cleared Fujirebio’s cerebrospinal fluid Aβ42/40 immunoassay for clinical use (May 2022 news). The agency later gave the nod to two Roche CSF immunoassays, for p-tau181/Aβ42 and Aβ42/t-tau, as well (Dec 2022 news; Jun 2023 news).

Patients and doctors prefer blood tests for routine clinical use. The FDA ruled that Fujirebio’s new plasma assay is “substantially equivalent” to the company’s previously cleared CSF test. In multicenter testing on 499 cognitively impaired people, the blood test had a positive predictive value of 92 percent, and a negative predictive value of 97 percent, for detecting plaques found by amyloid PET scans or CSF tests. Importantly, fewer than 20 percent of patients fell into an indeterminate zone on this test. This is when their test is neither definitively positive nor negative. Indeterminate results require follow-up testing by PET or CSF.

Welcoming the news, the Alzheimer’s Association noted that it will present guidelines to help clinicians determine which patients to test, and when to test, at this summer’s Alzheimer’s Association International Conference in Toronto. The association previously published appropriate use recommendations for blood tests in clinical care (Hansson et al., 2022).

More than a dozen other companies are working on AD blood tests, as well. C2N Diagnostics submitted its plasma mass spec-based assay, which measures p-tau217 and Aβ42/40, to the FDA at around the same time as did Fujirebio last year (Aug 2024 conference news). C2N’s Precivity plasma test was previously certified for clinical use (Nov 2020 news). Certification applies a less rigorous standard, requiring tests to be accurate and reliable, but does not evaluate diagnostic value. Other companies, such as Quest Diagnostics and Eli Lilly, also have had their blood tests certified (Nov 2024 conference news).

In other Alzheimer’s news, Sens. Shelley Moore Capito (R-W.Va.) and Mark Warner (D-Va.), and Reps. Linda Sánchez (D-Calif.) and Darin LaHood (R-Ill.), today reintroduced the Concentrating on High-value Alzheimer’s Needs to Get to an End (CHANGE) Act to Congress. This bipartisan bill would require Medicare to reimburse doctors for assessing cognitive impairment during annual wellness visits and encourage them to refer cognitively impaired patients for further care. Blood tests would make this more feasible. First introduced in 2021, the act has been considered in every session since.—Madolyn Bowman Rogers

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References

News Citations

  1. FDA Approves Fujirebio’s CSF Test for AD—Quest Diagnostic Offers Plasma Test
  2. Blood Amyloid Test May Help Diagnose Alzheimer’s, but Questions Remain
  3. FDA Clears Roche’s CSF Aβ42/tTau Assay
  4. In Head-to-Head Testing, P-Tau217/Tau217 Comes Out on Top. By a Hair.
  5. Plasma Aβ Test Wins Approval—Are p-Tau Tests Far Behind?
  6. Some Alzheimer’s Blood Tests Are Racing Toward IVD Certification

Paper Citations

  1. Hansson O, Edelmayer RM, Boxer AL, Carrillo MC, Mielke MM, Rabinovici GD, Salloway S, Sperling R, Zetterberg H, Teunissen CE. The Alzheimer's Association appropriate use recommendations for blood biomarkers in Alzheimer's disease. Alzheimers Dement. 2022 Dec;18(12):2669-2686. Epub 2022 Jul 31 PubMed.

External Citations

  1. cleared for marketing

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