Biogen Advances Tau-Targeting Alzheimer’s Drug to Phase 3 Despite Mixed Phase 2 Data

Biogen reported mixed results Thursday from a mid-stage clinical trial of a treatment for Alzheimer’s disease that targets the protein tau. Like the better-known amyloid, tau is toxic to neurons and is believed to play a role in the cognitive decline of patients with the disease.

In the Phase 2 study, the Biogen drug, called diranersen or BIIB080, reduced levels of tau in the spinal fluid and brains of patients with early-stage Alzheimer’s. Those tau reductions also correlated to a slowing of cognitive decline, the company said.

Biogen investigated three escalating dosing regimens in its study, with the lowest dose showing the best results. For that reason, the study failed to achieve its primary efficacy goal, which was a dose response.

The company said it plans to move the medicine, diranersen, into a pivotal Phase 3 trial. The decision comes after the drug demonstrated an ability to lower tau and produce signs of clinical benefit at the lowest dose tested. Alzheimer’s disease has been the focus of repeated drug development efforts aimed at both amyloid and tau proteins.

While several amyloid-targeting therapies have reached the market in recent years, tau has remained a challenging target for pharmaceutical companies.