Diranersen (IONIS-MAPTRx/BIIB080) - (CELIA)

May 14, 2026: Ionis Pharmaceuticals, Inc. (NASDAQ: IONS) said partner Biogen reported topline results from the global Phase 2 CELIA trial of diranersen (IONIS-MAPT Rx/BIIB080), an investigational intrathecal antisense oligonucleotide targeting tau, in 416 participants with early Alzheimer’s disease (mild cognitive impairment due to AD or mild AD dementia) who had not previously received anti-amyloid therapy. CELIA did not meet its primary endpoint (dose response for change from baseline on CDR-SB at Week 76). However, pre-specified analyses of cognitive endpoints showed slowing of clinical decline across all doses, particularly with 60 mg every 24 weeks. Biomarkers showed robust reductions in CSF tau and tau pathology by tau PET across all studied doses, maintained throughout dosing. Safety/tolerability was generally consistent with the Phase 1b study; adverse event rates were comparable across dose groups, with a higher incidence of serious adverse events at the highest dose. Based on the biomarker and efficacy data, Biogen plans to advance diranersen to registrational development and engage with regulators; an ongoing long-term extension continues. Data are planned for presentation at AAIC 2026 and other scientific congresses.