Biogen’s Diranersen Slows Cognitive Decline in Phase 2 Alzheimer’s Trial at Rates Comparable to Approved Therapies

Biogen’s experimental Alzheimer’s drug diranersen slowed patients’ cognitive decline in a Phase 2 trial at rates roughly comparable to approved therapies. The results were reported on July 14, 2026. Different doses of diranersen produced improvements in patient performance on multiple cognitive tests compared with placebo.

The drug also lowered levels of the protein tau. Tau forms toxic tangles in the brain and is associated with memory loss and other Alzheimer’s symptoms. Diranersen is designed to target tau. Biogen plans to move diranersen into a Phase 3 trial based on the Phase 2 data.

Experts will wait for Phase 3 trial data before making final assessments of diranersen.