Researchers at Washington University School of Medicine in St. Louis have identified dozens of blood proteins whose levels change while patients are being treated with lecanemab, the anti-amyloid drug sold as Leqembi. The study followed 197 people with early symptomatic Alzheimer's disease and confirmed amyloid buildup, all of whom received infusions every two weeks for up to two years. Some of those proteins, the researchers report, could serve as biomarkers reflecting brain health and how the brain is responding to the drug.
The clinical problem here is a practical one. Anti-amyloid therapies clear amyloid plaques and have been shown to slow decline, though they neither cure the disease nor restore lost cognition. Response varies from person to person, and until now the only real way to check whether the drug is doing its job in a given patient has been expensive brain imaging. That leaves clinicians in the awkward position of prescribing an intensive, long-running infusion therapy without a straightforward way to tell an individual patient how it is going.
Suzanne Schindler, who led the work with co-senior author Carlos Cruchaga of the Department of Psychiatry, framed the gap bluntly: trial data show these treatments are likely to help the average patient with early symptoms, but the tools to monitor effects in one specific person are limited. A blood test that indicated whether amyloid was being cleared, and how the brain was changing in response, would fill that gap.
What the study offers is a shortlist of candidate markers rather than a finished test. Turning these protein signals into something a clinic can order would require showing that the changes track meaningfully with imaging results and with how patients actually fare over time, across larger and more varied groups of people than a single cohort of 197.