On 14 May, the biotechnology company Biogen announced topline results from its Phase II CELIA study evaluating diranersen (BIIB080), an investigational antisense oligonucleotide therapy targeting tau, in people with early Alzheimer’s disease (AD). According to the company, the results provide the first evidence from a study showing both reduction in Tau pathology and cognitive benefit in people with early AD.
CELIA is a global Phase II randomised, double-blind and placebo-controlled evaluating the efficacy, safety and tolerability of diranersen in people with early AD. The study enrolled 416 participants with mild cognitive impairment due to AD or mild AD dementia. The study evaluated three doses of diranersen administered intrathecally over a 76-week placebo-controlled treatment period. The primary endpoint assessed dose response for change from baseline on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) at week 76, while secondary and exploratory endpoints included additional clinical, biomarker and imaging measures, including cerebrospinal fluid (CSF) tau biomarkers and tau positron emission tomography (PET).
Although the study did not meet its primary endpoint assessing dose response on the CDR-SB scale, pre-specified analyses of cognitive endpoints showed slowing of clinical decline across all studied doses, particularly among participants receiving the lowest dose of diranersen (60 mg administered every 24 weeks). Diranersen also demonstrated robust reductions in tau pathology across all studied doses.
The safety and tolerability profile of diranersen was generally consistent with findings from the earlier Phase Ib study. Following the results, Biogen announced plans to advance diranersen into registrational development and engage with regulators on next steps. Data are expected to be presented at the Alzheimer’s Association International Conference 2026 (AAIC 2026) and other upcoming scientific congresses.
https://investors.biogen.com/news-releases/news-release-details/topline-results-phase-2-celia-study-diranersen-biib080-first
