Promising Phase 2 findings presented at the Alzheimer’s Association International Conference (AAIC) 2026 have demonstrated that the investigational therapy diranersen slowed cognitive decline while significantly reducing tau pathology in people with early Alzheimer’s disease, marking an important advance in the search for disease-modifying treatments. The results were presented by Professor Cath Mummery, Director of the UK Dementia Trials Network (UKDTN)
Diranersen slows cognitive decline and reduces tau pathology in encouraging Phase 2 trial results presented at AAIC 2026.
The global CELIA trial enrolled 416 people with early Alzheimer’s disease and evaluated diranersen, an investigational antisense therapy designed to reduce the production of tau protein, one of the key pathological hallmarks of the disease. Across 18 months of treatment, the study demonstrated consistent clinical benefits across all doses tested, with the strongest effects observed in participants receiving the 60 mg dose.
Compared with placebo, participants receiving the 60 mg dose experienced:
- 42% slower cognitive decline on the Alzheimer’s Disease Assessment Scale–Cognitive Subscale (ADAS-Cog);
- 50% slower decline on the Mini-Mental State Examination (MMSE); and
- 26% slower decline on the Clinical Dementia Rating–Sum of Boxes (CDR-SB), a measure of cognition and daily functioning.
The study also demonstrated substantial biological effects, reducing cerebrospinal fluid total tau levels by 50–65%. Importantly, diranersen is the first tau-directed therapy in a Phase 2 trial to show reductions in both cerebrospinal fluid tau and brain tau pathology measured by PET imaging.
Professor Cath Mummery said:
“The CELIA data provide some of the clearest evidence that reducing tau pathology can translate into clinically meaningful benefit. The magnitude of tau reduction and cognitive benefit observed in CELIA is among the most compelling reported to date in Alzheimer’s disease drug development and supports advancing diranersen to Phase 3 development.”
The treatment was generally well tolerated, with most adverse events reported as mild or moderate. More than 90% of participants who completed the placebo-controlled phase elected to continue into the long-term extension study.
The results underscore the growing momentum in Alzheimer’s disease therapeutic development and the importance of a strong clinical trials infrastructure to evaluate innovative treatments efficiently. As more disease-modifying therapies progress through clinical development, the UK Dementia Trials Network (UKDTN) is working with partners across the UK to strengthen the nation’s capacity to deliver high-quality dementia clinical trials and accelerate access to research opportunities for people living with dementia.
The CELIA trial was sponsored by Biogen, with UK participation supported by the NIHR University College London Hospitals Biomedical Research Centre. Biogen has announced plans to advance diranersen into Phase 3 clinical development, with additional analyses from the CELIA study and its ongoing long-term extension expected to be presented at future scientific meetings.
By UKDTNAdmin