Blood markers may help track plaque clearance with lecanemab in Alzheimer’s

Clinical takeaway: Blood biomarkers could eventually help clinicians assess amyloid clearance and counsel patients receiving lecanemab about prognosis. These findings need validation before a blood test can guide treatment duration or replace established monitoring.

When patients with early Alzheimer’s disease ask whether lecanemab is working for them, clinicians have limited ways to answer. A longitudinal study in The Lancet Neurology suggests that blood proteins may eventually provide different kinds of information: some were associated with amyloid clearance, while others were associated with the pace of cognitive decline.

Researchers measured 130 plasma proteins in 197 patients receiving lecanemab through a single memory clinic. Blood samples and clinical assessments were collected approximately every six months for up to two years. Concentrations of 34 proteins changed significantly with treatment. Markers including phosphorylated tau shifted toward levels seen in people without amyloid buildup or cognitive impairment, while some markers related to inflammation moved further from those levels.

Among 57 patients who underwent amyloid PET imaging after about 18 months of treatment, 29 had become amyloid negative. Several blood proteins differed between those patients and the 28 who remained amyloid positive. If validated, these markers could help clinicians decide when to order follow-up imaging. They cannot yet confirm plaque clearance in an individual patient.

Initial levels of a different group of proteins were associated with subsequent cognitive change. That finding could eventually help clinicians counsel patients about their likely course.

The cohort came from one clinic and was predominantly White. Testing in larger, more diverse groups will be needed before these markers can inform individual treatment decisions.

“It would be very helpful to have a blood test that told us how the treatment was working in an individual patient, especially whether amyloid is being cleared from the brain and how the brain is changing,” said co-senior author Suzanne Schindler, MD, PhD, of Washington University School of Medicine in St. Louis.

Source: Mu R, et al. (2026 Sep 24) Lancet Neurol. Dynamic changes in plasma biomarkers of Alzheimer's disease in patients treated with lecanemab: a longitudinal cohort study