Biogen’s diranersen slowed cognitive decline in Phase 2 trial at rates similar to approved Alzheimer’s drugs

Biogen’s experimental Alzheimer’s drug diranersen slowed patients’ cognitive decline in a Phase 2 trial at rates roughly comparable to approved therapies, Stat reported on July 14, 2026. The mid-stage study showed that different doses of the drug produced improvements on several patient performance tests compared with placebo.

Diranersen also reduced levels of the protein tau, which forms toxic tangles in the brain and is linked to memory loss and other Alzheimer’s symptoms.

Biogen plans to move the drug into a Phase 3 trial on the strength of these data. Alzheimer’s specialists said the results indicated an effect on disease progression. The article noted that experts will wait for data from the larger Phase 3 study before making final assessments of diranersen’s benefits.