Labcorp, Quest add new blood tests for Alzheimer's, brain tissue damage

The twin clinical testing giants Labcorp and Quest Diagnostics have each, in the past week, added to their portfolios new blood tests that aim to peek into the workings of the human brain. 

First, Labcorp announced the availability of a commercial test for glial fibrillary acidic protein, a biomarker released into the bloodstream by certain cells within the brain following neurological damage.

The company said the GFAP immunoassay could help track the early progression of diseases such as Alzheimer's, multiple sclerosis or glioblastoma as well as help identify traumatic brain injuries.

Labcorp’s blood-based neurology catalog also includes biomarker tests for the Alzheimer’s hallmark proteins of beta amyloid and tau as well as for neurofilament light chain, which has been linked to dementia, Huntington’s disease and amyotrophic lateral sclerosis, better known as ALS.

Meanwhile, Quest will begin offering a blood screener for a specific type of Alzheimer’s protein—phosphorylated tau 217, or pTau-217—within its AD-Detect product line, which was launched last year targeting general consumers amid some criticism over its accuracy and need for follow-ups.

The pTau-217 test will join Quest assays for pTau-181 and beta amyloid, in addition to the Alzheimer’s risk factor apolipoprotein E, to help evaluate patients displaying cognitive impairment.

“Testing to assess Alzheimer's disease has changed rapidly in the last few years, and we expect this area to continue evolving,” Quest’s medical director for neurology, Michael Racke, M.D., said in a statement

“The future of assessing risk or diagnosing AD will likely include a variety of testing modalities and biomarkers, including blood, to help clinicians identify patients in the early stages of disease progression,” Racke said. “When examined with cognitive test results, p-tau217 has the potential to aid diagnosis, and will play a valuable role in assessing patients with cognitive impairment, especially when combined with other tests.”

The biomarkers chosen by Labcorp and Quest have also recently been advanced by other developers. 

Earlier this month, Abbott received an expanded FDA clearance for the use of the GFAP protein within its hand-held, cartridge-based whole blood test for detecting concussions or mild traumatic brain injuries. 

The company’s i-STAT Alinity diagnostic device—which also relies on the brain damage biomarker ubiquitin C-terminal hydrolase L1—has its sights set on one day providing quick analyses on the sidelines of sporting events, but currently its FDA green light only extends as far as locations with certified laboratory testing privileges.

Previous clinical data showed that checking that pair of biomarkers could also help predict how well a patient will recover from a TBI in the weeks that follow, as well as their chances of long-term complications such as comas, disability or death.

At the same time, pTau-217 recently collected an FDA breakthrough designation as part of an Alzheimer’s blood test being developed by Roche and Eli Lilly. Roche’s Elecsys plasma assay quantifies the protein, with positive results correlating with high chances that a patient may display amyloid plaques on a PET scan.

Last month also saw the FDA publish a new draft guidance on how the agency may review Alzheimer’s therapy hopefuls saying measures showing amyloid reduction could serve as a surrogate in clinical trials but did not go as far as to say that it could serve as a study’s primary endpoint alone.

With Roche’s help, Eli Lilly said it believes pTau-217 could potentially help identify patients eligible for clinical trials in Alzheimer’s or point them to approved therapies.