Healthcare
Diranersen Results at AAIC Provide First Evidence That Targeting Tau May Slow Cognitive Decline, Signaling Momentum Toward Addressing the Full Pathobiology of Alzheimer's
Today at the Alzheimer's Association International Conference (AAIC), Biogen presented results from the phase 2 CELIA study of diranersen (BIIB080), an investigational therapy designed to target tau in people with early Alzheimer's disease. While the study failed to meet its primary endpoint of demonstrating dose response-related effects on change in Clinical Dementia Rating-Sum of Boxes (CDR-SB), the new data showed strong biomarker effects, including reductions in CSF tau and tau PET, as well
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New data show greater tau reduction at higher doses but strongest clinical signal at lowest dose, raising key questions about optimal dosing in further trials, says the ADDF NEW YORK, July 14, 2026 /PRNewswire/ -- Today at the Alzheimer's Association International Conference (AAIC), Biogen presented results from the phase 2 CELIA study of diranersen (BIIB080), an investigational therapy designed to target tau in people with early Alzheimer's disease. While the study failed to meet its primary endpoint of demonstrating dose response-related effects on change in Clinical Dementia Rating-Sum of Boxes (CDR-SB), the new data showed strong biomarker effects, including reductions in CSF tau and tau PET, as well as clinical effects at lower doses, raising important questions about the optimal dose and design of future trials. "These are the first data from a randomized trial to show a tau-targeting drug producing both a robust biomarker effect and a signal of clinical benefit," said Laura Nisenbaum, PhD, Interim Chief Science Officer at the Alzheimer's Drug Discovery Foundation (ADDF). "Tau is one of the two defining pathologies of Alzheimer's disease and has long been difficult to target, which makes these results all the more notable. But the dose-response discordance between the biomarker and clinical endpoints raises important questions about the optimal level of tau reduction and the right dose of diranersen to test in subsequent studies. Those questions will be central to designing the strongest possible phase 3 program." The central unanswered question from the study is the discordance between the biomarker and clinical findings. Higher doses led to greater tau reduction, while the lowest dose showed the strongest clinical signal. Biogen has said these results support advancing diranersen into further trials as it continues to analyze the full data to understand why the biomarker and clinical effects diverged and what that means for future trial design. With disease-modifying anti-amyloid therapies now available, tau represents an important opportunity to expand Alzheimer's treatment options beyond a single target. The Alzheimer's therapeutic pipeline continues to broaden, with 75% of current clinical trials aimed at pathways beyond amyloid and tau, including inflammation, neurotransmitters, and metabolic dysfunction. This growing range of potential therapeutic approaches is essential to the future of Alzheimer's care, as the field moves toward treatments that can be individualized and combined based on each person's underlying disease biology.