At the Alzheimer’s Association International Conference, Biogen presented Phase II Celia data for diranersen (BIIB-080), a tau-lowering antisense oligonucleotide. Researchers reported clinical and biomarker signals that supported moving into Phase III despite a formal phase-2 primary endpoint miss related to dose-response. Presentation details emphasized that tau reductions and several cognitive and functional endpoints favored diranersen across doses, with strongest effects reported in the lowest dose arm. The program’s next step is likely to intensify scrutiny on whether effect sizes are durable and statistically robust in larger, confirmatory testing. The reaction reinforced how tau-targeting is still being validated in the clinic—both for biological engagement and for clinical meaningfulness—after years of mixed results in the field.