Alzheimer drug targeting tau clears first phase-2 hurdle

Tau is a protein that plays a structural role in healthy brain cells. In Alzheimer’s disease, it clumps into so-called neurofibrillary tangles: twisted bundles that disrupt neuronal function and eventually lead to cell death. Most approved Alzheimer’s therapies so far have targeted amyloid, another protein that aggregates in the disease. Tau offers an alternative target.

What the study examined

Biogen conducted a phase-2 clinical trial with diranersen, a treatment specifically designed to target tau. In May 2026, the company announced positive results from the study. The researchers will present detailed outcomes on 14 July at the Alzheimer’s Association International Conference. Full details on the magnitude of the effect and precise outcome measures are not yet publicly available.

Phase-2 studies are designed to assess safety and provide an initial signal of efficacy. They are smaller than the phase-3 studies required for regulatory approval. Results are therefore preliminary and should be interpreted with caution.

Tau as a new target in Alzheimer’s disease

Scientific interest in tau as a therapeutic target is growing. Amyloid-targeting therapies have demonstrated they can clear amyloid, but clinical benefit for patients has been limited for many of these drugs. That has driven increased attention toward tau and other mechanisms involved in Alzheimer’s.

Diranersen belongs to the class of antisense oligonucleotides: small pieces of genetic material that can suppress the production of a specific protein. This approach has also been used in other brain diseases, such as spinal muscular atrophy.

Whether diranersen will advance to phase 3 depends on the details shared at the conference. For the broader Alzheimer’s community, the data presentation is one of the most anticipated moments of the year.

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Search terms: tau protein Alzheimer therapy, antisense oligonucleotide neurodegeneration, neurofibrillary tangles cell death