Biogen’s anti-tau antisense oligonucleotide diranersen (BIIB-080) showed cognitive slowing in its phase 2 Celia trial presentation, reinforcing the company’s decision to advance into phase 3. At the Alzheimer’s Association International Conference, Catherine Mummery of University College London’s Dementia Research Center presented data indicating tau-lowering translated into slowing on multiple clinical and biomarker measures. Despite missing the formal phase 2 primary endpoint related to establishing dose-response, the trial reported favorable direction across five of six clinical endpoints, with the strongest effects reported in the 60 mg dose group. Tau reductions were described as profound across doses, including reductions measured with PET imaging analyses referenced in conference discussions. Market scrutiny remains focused on whether the effect size will hold in phase 3, but the new data provides Biogen a stronger platform for the next regulatory and investment milestone.