Biogen’s tau-lowering antisense oligonucleotide diranersen (BIIB-080) drew new attention after presentations of Phase 2 “Celia” data at the Alzheimer’s Association International Conference (AAIC). Researchers from University College London’s Dementia Research Center reported that multiple clinical and biomarker measures favored diranersen versus placebo, despite the study’s formal miss on a primary dose-response endpoint. In the 60-mg arm, investigators reported slowing on commonly used cognitive and functional scales, including Alzheimer’s Disease Assessment Scale–13 (ADAS-Cog 13) and CDR-SB, alongside “profound” tau reductions with PET-aligned biomarker changes. Biogen has continued advancing diranersen into Phase 3, framing the results as proof-of-concept. Independent coverage also highlighted the internal debate around strength of evidence—stock moves reflected skepticism among some analysts—while other specialists pointed to the magnitude of decline in endpoints as broadly comparable with the direction of effect seen in approved amyloid-targeting therapies. The dataset now sets up the next validation step in a larger trial rather than settling the question on its own.