The Elecsys pTau181 test measures for the phosphorylated Tau 181 protein in human plasma. The protein is considered as a marker that patients aged 55 and older, who are experiencing cognitive decline, are unlikely to have Alzheimer's-related amyloid pathology, according to the company's news release.
Developed in collaboration with Eli Lilly and Company, the minimally invasive test provides information that clinicians can use alongside other clinical assessments.
The FDA approval represents a breakthrough for Alzheimer's testing beyond specialty settings, expanding into primary care offices, where most patients look for help when first experiencing cognitive issues.
According to Roche, approximately 92 percent of patients with mild cognitive impairment remain undiagnosed and therefore cannot explore potential therapeutic treatments.
"By bringing Alzheimer's blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys," Brad Moore, president and CEO of Roche Diagnostics North America, said in the release. "This milestone reflects Roche's leadership in diagnostics and our commitment to expanding access to innovative testing for patients and their clinicians."
More than 7 million Americans live with Alzheimer's disease, which is a complex condition involving multiple pathologies, the company said. Until now, biomarker testing has been largely confined to specialty settings such as neurology clinics.
The test showed strong performance in ruling out Alzheimer's pathology during clinical trials. A multicenter study of 312 participants showed the test achieved a 97.9 percent negative predictive value in an early disease-stage, low-prevalence population reflective of primary care settings. The fully automated test runs on Roche's installed base of more than 4,500 instruments already in clinical laboratories across the United States.
"This is another important step toward expanding access to Alzheimer's disease diagnostic tools," Joanne Pike, the association's president and chief executive officer, said in a statement on Sunday. "At the same time, it is important to understand this test is designed to rule out the presence of amyloid plaques. It is not a test that will give an Alzheimer's disease diagnosis, nor is it a standalone tool for detection."
According to the association, the test can help primary care physicians determine which patients do not require Alzheimer's-related follow-up tests such as positron emission tomography scans or cerebrospinal fluid analysis, potentially preventing unnecessary specialized testing for those whose cognitive issues stem from non-Alzheimer's causes.
"By using a 'rule out' initial tool in the primary care setting, we can help people who are not living with Alzheimer's get to the root of their cognitive symptoms faster, while ensuring those who may have the disease are referred for appropriate testing, definitive diagnosis and early treatment," Pike said.
The association published clinical practice guidelines earlier this year for using blood biomarker tests in specialty care settings. The organization urges providers across all clinical settings to take advantage of the guidance on blood biomarker testing alongside clinical judgment.
According to Roche, the clearance may help healthcare providers to assess the early stages of cognitive issues sooner as well as improve the quality of referrals to specialists, which in return will preserve neurologists’ resources for patients with a greater need. The test also has the potential to cut down on the use of more invasive and costly procedures such as PET scans and cerebrospinal fluid testing.
Roche recently received CE Mark certification in Europe for the test, making it the first In Vitro Diagnostic Regulation-certified blood test to help rule out Alzheimer's-associated amyloid pathology.
That test showed 91.7 percent accuracy in identifying individuals with amyloid plaques and 97.3 percent accuracy in identifying those without plaques in a clinical study of 499 cognitively impaired adults.