Eisai Presents Anti-MTBR Antibody Etalanetug (E2814) Plasma Biomarker Data at AAIC 2026 Featured Research Session: Etalanetug Reduced Plasma MTBR-Tau243 by 78% at 3 Months and by More Than 90% at 9 Months, With the Biomarker Largely Absent in Healthy Adults and Detected Only in Patients With Dominantly Inherited Alzheimer's Disease (DIAD), Reflecting Disease-Related Tau Neurofibrillary Tangle Pathology That Blood-Test Monitoring Can Now Track
Eisai announced Monday July 13, 2026 that its investigational anti-microtubule-binding region (MTBR) tau antibody etalanetug (development code E2814) reduced levels of plasma extracellular MTBR-tau243 (eMTBR-tau243), a novel fluid biomarker of Alzheimer's disease tau tangle pathology, in findings presented during a Featured Research Session at AAIC 2026 in London. Etalanetug reduced plasma eMTBR-tau243 by 78% at 3 months and by more than 90% at 9 months. The biomarker was largely absent in healthy adults and detected only in patients with dominantly inherited Alzheimer's disease (DIAD), suggesting it reflects disease-related tau pathology at the pathological source (neurofibrillary tangle formation) rather than tau physiology broadly. eMTBR-tau243 consists of tau fragments that include amino acid residue 243 and MTBR sequences, arising during the formation of neurofibrillary tangles, and can now be measured with a blood test to track tau pathology non-invasively. Etalanetug is Eisai's second-generation Alzheimer's antibody program beyond lecanemab (LEQEMBI, amyloid protofibril-directed), extending the company's franchise from amyloid to tau.