In short
BIIB080 is an investigational antisense oligonucleotide being studied for Alzheimer's disease. Two Phase 2 trials were registered to test it in mild cognitive impairment due to Alzheimer's disease and mild Alzheimer's dementia. One trial planned to enroll 735 participants but was withdrawn before starting. The other, called CELIA, is authorised and aims to enroll 416 participants aged 50 to 80.
Key points
- BIIB080 is an investigational drug that targets tau protein production in the brain.
- Two Phase 2 trials were registered for Alzheimer's disease.
- The CELIA trial plans to enroll 416 participants aged 50 to 80.
- A larger 735-participant trial was withdrawn before it began.
- Both trials measure changes on the Clinical Dementia Rating-Sum of Boxes (CDR-SB) scale.
- BIIB080 is given by intrathecal injection into the cerebrospinal fluid.
What is BIIB080?
BIIB080 is an investigational antisense oligonucleotide. Its full chemical name is 2ʹ-O-(2-methoxyethyl) antisense oligonucleotide targeting microtubule-associated protein tau pre-mRNA. An antisense oligonucleotide is a short, chemically synthesised piece of genetic material designed to bind to a specific messenger RNA molecule and prevent it from being used to make a protein. BIIB080 has no marketing authorisation in these records, meaning it is still being studied and is not an approved medicine.
How does BIIB080 work?
BIIB080 targets the pre-mRNA of the microtubule-associated protein tau. In Alzheimer's disease, tau protein can build up inside brain cells and form tangles, which are thought to contribute to cell damage and symptoms. By reducing the production of tau, BIIB080 aims to slow down this process. The exact clinical benefit is still being investigated in clinical trials.
Which conditions is BIIB080 being studied for?
- Mild cognitive impairment due to Alzheimer's disease — an early stage of memory and thinking problems caused by Alzheimer's disease, where daily functioning is mostly preserved.
- Alzheimer's disease dementia — a more advanced stage where memory, thinking and daily function are clearly affected.
How is BIIB080 given?
BIIB080 is given by intrathecal injection, which means it is injected directly into the cerebrospinal fluid that surrounds the brain and spinal cord. The trial records list doses of 60 mg and 115 mg in one trial, and the other trial does not report a dose (listed as 0 mg in the register). In the trials, it is compared with a placebo: an artificial cerebrospinal fluid diluent given as a solution for injection. The trials also use imaging agents (Neuraceq, VIZAMYL, MK-6240) given intravenously to visualise amyloid and tau in the brain.
What do the clinical trials show?
Two Phase 2 trials are registered for BIIB080 in Alzheimer's disease. One trial (NCT05399888) was planned to enroll 735 participants but has been withdrawn, meaning it did not go ahead. The other trial, also under the same NCT number but with the study name CELIA, is authorised and plans to enroll 416 participants. Both are interventional studies, meaning participants receive the drug or placebo and are followed over time. Because the trials are at an early stage or did not start, there are no results yet to report.
Who can take part in these trials?
Both trials include participants aged 50 to 80 years with either mild cognitive impairment due to Alzheimer's disease or mild Alzheimer's disease dementia. The authorised CELIA trial plans to enroll 416 participants. The withdrawn trial would have enrolled 735 participants. Detailed inclusion and exclusion criteria are available in the registry records.
What are the trials measuring?
The main outcome in both trials is the change from the start of the study to Week 76 on the Clinical Dementia Rating-Sum of Boxes (CDR-SB). The CDR-SB is a scale used to measure how severe a person's dementia is, covering memory, orientation, judgment, community affairs, home and hobbies, and personal care. A higher score means more severe symptoms. The trials aim to see whether different doses of BIIB080 change this score compared with placebo.