Biogen’s Diranersen Phase 2: Tau Reduction Shows Cognitive Signals Despite Missed Dose-Response Endpoint

Biogen reported that the Phase 2 CELIA trial of diranersen achieved robust reductions in CSF tau and tau pathology and showed slowing of cognitive decline across doses—most notably at 60 mg every 24 weeks—despite not meeting the primary dose-response endpoint (CDR-SB at Week 76). Safety was generally consistent with prior data, with more serious adverse events at the highest dose. Biogen plans to advance diranersen to registrational development and will present further data at AAIC 2026.