Lowered levels of phosphorylated (P)-tau217 and glial fibrillary acidic protein (GFAP) in the blood indicate downstream treatment effects of beta amyloid (Aβ) clearance from the brain, new research shows.
Investigators found that changes in levels of these plasma biomarkers were positively correlated with percent change in amyloid plaque levels as shown on positron-emission tomography (PET).
The results suggest these biomarkers could be used instead of the more expensive, and not always readily available, PET scans to monitor patients taking anti-amyloid agents.
"We probably can't measure complete amyloid removal with a blood test, but we can see that something's happening and we know whether or not we've got engagement," study investigator Michael Pontecorvo, PhD, vice president of clinical development at Avid Radiopharmaceuticals, the biomarker arm of Lilly, told Medscape Medical News.
The findings were presented at the American Academy of Neurology (AAN) 2022 Annual Meeting.
New Possibilities
The phase 2 trial of donanemab (TRAILBLAZER-ALZ) is a randomized, double-blind, placebo-controlled study in patients with early, symptomatic Alzheimer's disease (AD). The study included 257 patients. Of these, 131 were randomly assigned to receive donanemab and 126 to receive placebo.
The study, published last year in The New England Journal of Medicine,showed that the change from baseline in the primary endpoint of integrated Alzheimer's Disease Rating Scale score at 76 weeks was −6.86 with donanemab and −10.06 with placebo, for a difference of 3.20 (95% CI, 0.12 – 6.27;
