Biogen’s phase 2 Celia trial of tau-lowering antisense oligonucleotide diranersen (BIIB-080) showed a cognitive signal that—despite a phase 2 dose-response miss—supported moving the program into phase 3. At AAIC, Catherine Mummery of University College London/Dementia Research Center presented updated clinical and biomarker data alongside tau reductions from PET and other measures. The presentation emphasized that multiple clinical endpoints favored diranersen versus placebo and that improvements were most pronounced at the lowest tested dose. Biogen framed the results as proof-of-concept for slowing disease progression through tau reduction. In related coverage, Biogen also defended the readout with investors, noting that the effect size and tau-target engagement aligned with those approved comparators’ magnitude—even as clinicians continued to debate whether the study clears the threshold for meaningful benefit. Overall, the Celia update keeps anti-tau strategy in the spotlight for early Alzheimer’s, while also sharpening scrutiny on dose selection and endpoint interpretation as the company prepares larger confirmatory testing.