Dive Brief:

• Labcorp is now offering a blood-based biomarker test in the U.S. to support the diagnosis of Alzheimer's disease.
• The immunoassay measures the ratio of ptau-217 and beta amyloid 42, two distinct biomarkers of Alzheimer's, according to the Wednesday announcement. The Global CEO Initiative on Alzheimer’s Disease has called ptau-217 one the most promising blood-based biomarkers for amyloid status.
• Manufacturers of Alzheimer’s drugs have identified blood tests as a way to reduce the reliance on imaging and cerebrospinal fluid assays and to accelerate diagnosis and treatment.

Dive Insight:

Approvals of disease-modifying drugs such as Eisai and Biogen’s Leqembi and Eli Lilly’s Kisunla have given people with Alzheimer’s new options. The authorizations support the use of the medicines in patients with early symptoms, creating a pressure to diagnose and treat people before the disease progresses. 

Labcorp said the average time between onset of symptoms and diagnosis of Alzheimer's is approximately 2.8 years, although that figure comes from a paper published in 2002. CEOi, which lists Biogen, Eisai and Lilly among its members, sees blood-based biomarker testing as more scalable than the amyloid PET scans and CSF tests currently used to confirm an Alzheimer’s diagnosis. 

The ptau-217/beta amyloid 42 ratio test is part of Labcorp’s push to help scale and accelerate diagnosis. Patients can provide blood samples at the physician's office or any of Labcorp’s more than 2,000 patient service centers in the U.S. 

Labcorp said performance is substantially equivalent to CSF assays and PET imaging cleared by the Food and Drug Administration. The sensitivity and specificity of the confirmatory test are both 95%, according to Labcorp. CEOi determined sensitivities and specificities of 90% and higher are acceptable.

Labcorp is presenting data at the American Association of Neurology's 2025 Annual Meeting, which began Saturday and goes through Wednesday.

The company called the product a first-of-its-kind immunoassay. Competition for the Alzheimer’s blood test market is intensifying, though. Keisuke Naito, chief operating officer at Eisai, said on an earnings call in February that “several diagnostic companies have submitted IVD applications for confirmatory testing using high-precision composite score, including Aβ and ptau-217 evaluation system.”

Roche received FDA breakthrough designation for a ptau-217 blood test in 2024. Bruno Eschli, head of investor relations at Roche, said at virtual neurology event Friday that “ptau-217 will be used as a triage test initially and has the potential to become the first blood-based rule in test in a second step, thereby revolutionizing the timely diagnosis of Alzheimer's.”