Emerging Tau-Targeting Antibody for Alzheimer Disease Receives FDA Fast Track Designation

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The US FDA has granted Fast Track designation to etalanetug (E2814), an investigational anti-microtubule binding region (MTBR) tau antibody under development by Eisai Co., Ltd, for the treatment of Alzheimer disease (AD). Fast Track status is designed to facilitate development of therapies for serious conditions that address unmet medical needs and enables increased interaction with the FDA during the review process.

AD is a progressive neurodegenerative disorder characterized by amyloid-beta plaques and tau neurofibrillary tangles in the brain. Research has demonstrated that both amyloid-beta protofibrils and tau tangles contribute to neurodegeneration. Etalanetug targets tau species containing MTBR, which are implicated in the spread of tau pathology between brain regions. The antibody was discovered through a research collaboration between Eisai and University College London.

In a phase 1/2 clinical trial (Study 103; NCT04971733) in participants with dominantly inherited AD, treatment with etalanetug demonstrated target engagement with MTBR-tau species in cerebrospinal fluid. Investigators reported a reduction in cerebrospinal fluid MTBR-tau243, a biomarker of tau pathophysiology, and a trend toward reduced tau positron emission tomography signal, suggesting suppression of tau accumulation.

Etalanetug is currently being evaluated in combination with lecanemab, an anti-amyloid-beta protofibril antibody, in 2 clinical trials: the phase 2/3 Tau NexGen study (NCT05269394) in dominantly inherited AD, and the phase 2 Study 202 (NCT06602258) in sporadic early AD.

According to Eisai, therapies directed at tau, following the development of amyloid-targeting treatments, could represent an additional advance in the treatment of AD. The company emphasized neurology as a key therapeutic area and stated its commitment to advancing research in dementia and other diseases with high unmet need.

Source: Eisai Co., Ltd. Anti-MTBR (microtubule binding region) Tau Antibody Etalanetug Granted FDA Fast Track Designation. News release. September 17, 2025. Accessed September 23, 2025. https://www.eisai.com/news/2025/news202564.html