CELIA

Active not recruitingPhase 2

A Study to Learn About the Safety of Diranersen (BIIB080) Injections and Whether They Can Improve Symptoms of Participants With Mild Cognitive Impairment Due to Alzheimer's Disease (AD) or Mild AD Dementia Between 50 to 80 Years of Age

A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study to Assess the Efficacy, Safety, and Tolerability of BIIB080 in Subjects With Mild Cognitive Impairment Due to Alzheimer's Disease or Mild Alzheimer's Disease Dementia

Lead sponsor

Biogen

Asset

Diranersen

Listed sites

138

Recruiting sites

Enrollment

416

actual

Study population

Alzheimer’s disease, MCI / preclinical Alzheimer’s

Key I/E criteria

•MCI due to AD / mild AD dementia•Amyloid biomarker required (PET/CSF)•CDR global 0.5•MMSE 21-30•MRI contraindications excluded

Primary endpoint

•Clinical Dementia Rating-Sum of Boxes (CDR-SB)

Footprint

Where this trial recruits

Site locations as reported to ClinicalTrials.gov. Site count is not enrollment count; per-site enrollment is not available from source.

Identifiers

Registered as

Secondary ID2022-501644-15EU CT Number

Org study ID247AD201

NCT IDNCT05399888

Timeline

Milestones

Study first posted2022-06-01actual

Study start2022-08-24actual

Primary completion2026-03-11actual

Last update posted2026-06-30actual

Study completion2028-06-06estimated

Assets

Drug assets

Diranersen

Study populations

Who this study enrolls

Alzheimer’s diseaseMCI / preclinical Alzheimer’s

Eligibility

Who can enroll

Minimum age50 Years

Maximum age80 Years

SexAll

Healthy volunteersNot accepted

Inclusion criteria

Key Inclusion Criteria for Placebo-controlled Period:

•Must meet all the clinical staging criteria for MCI due to AD (Stage 3) or mild AD dementia (Stage 4) according to the National Institute on Aging at National Institutes of Health and the Alzheimer's Association (NIA-AA) and must have the following at Screening Visit 1:

1. Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Delayed Memory Index score of ≤85, indicative of objective evidence of memory impairment.

2. CDR global score of 0.5 for MCI due to AD or 0.5 or 1 for mild AD dementia

3. MMSE score of 21 to 30 (inclusive).

4. CDR Memory Box score of ≥0.5.

•Evidence of amyloid pathology as measured by positive emission tomography (PET) or cerebrospinal fluid (CSF) sampling.

•Must have 1 care partner who, in the Investigator's judgment, has frequent and sufficient contact with the participant (at least 10 hours/week) to be able to provide accurate information about the participant's cognitive and functional abilities.

Key Inclusion Criteria for LTE Period

•Ability of the participant and/or his/her legally authorized representative (e.g., parent, spouse, or legal guardian), where local regulations and institutional practices permit, as appropriate and applicable, to understand the purpose and risks of the study, to provide informed consent, and to authorize the use of confidential health information in accordance with national and local privacy regulations. Incapacitated individuals will not be enrolled in the EU (European Union) and other countries where local laws, regulations, and practices do not permit their inclusion.

•Participants must have completed the placebo-controlled period of the study, including the Week 76 visit.

•Participants must have taken at least 5 doses of diranersen or placebo during the placebo-controlled period.

•Medically able to undergo the study procedures (including LP [lumbar puncture]) and to adhere to the visit schedule at the time of study entry into the LTE period, as determined by the Investigator.

•Apart from a clinical diagnosis of AD, the participant must be in good health as determined by the Investigator, based on medical history.

Exclusion criteria

for Placebo-controlled Period:

•Known allergy to diranersen or a history of hypersensitivity to any of the inactive ingredients in the drug product.

•Previous participation in this study or previous studies with diranersen.

•Use of non-disease-modifying AD medications (including but not limited to donepezil, rivastigmine, galantamine, tacrine, and memantine) at doses that have not been stable for at least 8 weeks prior to Screening Visit 1 and during the screening period up to Day 1.

•Use of any commercially available disease-modifying AD medications such as anti-amyloid monoclonal antibodies.

•Prior participation in any active or passive immunotherapy study targeting Aβ, unless documentation of receipt of placebo is available.

•Prior participation in any passive immunotherapy study targeting tau, unless the last administration occurred 6 months or 5 half-lives, whichever is sooner, prior to Screening or documentation of receipt of placebo is available.

•Prior participation in any study involving an investigational treatment targeting tau that is not a passive immunotherapy, unless documentation of receipt of placebo is available.

•Prior participation in a study of any other agent(s) not included in exclusion criteria 5, 6, and 7 with a purported disease-modifying effect in AD within 12 months, unless documentation of receipt of placebo is available.

•Prior participation in a study of any gene therapy with a purported disease-modifying effect in AD, unless documentation of receipt of placebo is available.

•Current use or previous use of medications with a purported disease-modifying effect in AD, outside of investigational studies.

•Any vaccination given within 10 days prior to Day -1. Coronavirus disease 2019 (COVID-19) vaccinations using RNA or deoxyribonucleic acid (DNA) technology are allowed during the study, as well as other types of immunization/vaccination/booster, except during the 10 days before and after clinic visits.

•Contraindications to having a brain magnetic resonance imaging (MRI) [e.g., MRI-incompatible pacemaker; MRI-incompatible aneurysm clips, artificial heart valves, or other metal foreign body; claustrophobia that cannot be medically managed]. If the MRI compatibility of implanted devices is unknown, the participant must be excluded from the study.

•Current enrollment or a plan to enroll in any interventional clinical study in which an investigational treatment or approved therapy for investigational use is administered within 52 weeks prior to the Baseline Visit.

Key Exclusion Criteria for LTE Period

•Any medical or psychiatric contraindication or clinically significant abnormality that, in the opinion of the Investigator, will substantially increase the risk associated with the participant's enrollment in and completion of the study.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Endpoints (8)

What's being measured

Protocol endpoints and posted registry outcome measures, grouped into outcome categories. Composite endpoints show their component event types. Standard codes (LOINC, SNOMED CT) are shown where available.

Coverage by outcome category

Global cognition

Function / daily living

Safety / tolerability / PK

Global cognition

6 endpoints

Primary/protocol endpoint

Dose response in Change From Baseline to Week 76 on the CDR-SB

Time frame:Baseline to Week 76

Clinical Dementia Rating-Sum of Boxes (CDR-SB)

change from baseline, improvement

Secondary/protocol endpoint

Change From Baseline to Week 76 on the CDR-SB

Time frame:Baseline to Week 76

Clinical Dementia Rating-Sum of Boxes (CDR-SB)

change from baseline, improvement

Secondary/protocol endpoint

Change From Baseline to Week 76 on the Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-Cog 13)

Time frame:Baseline to Week 76

ADAS-Cog

change from baseline, improvement

Secondary/protocol endpoint

Change From Baseline to Week 76 on the Mini Mental State Examination (MMSE)

Time frame:Baseline to Week 76

Mini-Mental State Examination (MMSE)

change from baseline, improvement

Secondary/protocol endpoint

Change From Baseline to Week 76 on the Modified Integrated Alzheimer's Disease Rating Scale (iADRS)

Time frame:Baseline to Week 76

ADAS-Cog

change from baseline, improvement

Secondary/protocol endpoint

Change From Baseline to Week 76 on the Alzheimer's Disease Composite Score (ADCOMS)

Time frame:Baseline to Week 76

ADAS-Cog

change from baseline, improvement

Function / daily living

1 endpoint

Secondary/protocol endpoint

Change From Baseline to Week 76 on the Alzheimer's Disease Cooperative Study Activities of Daily Living for Mild Cognitive Impairment (ADCS-ADL-MCI)

Time frame:Baseline to Week 76

ADCS-Activities of Daily Living (ADCS-ADL)

change from baseline, improvement

Safety / tolerability / PK

1 endpoint

Secondary/protocol endpoint

Number of Participants With Treatment-Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs)

Time frame:From first dose of study drug up to end of study of placebo-controlled period (up to Week 96)

event count, event

Provenance

Sources

Trial identity, design, statusClinicalTrials.gov API v2

Snapshot dateJuly 21, 2026

Endpoint classificationDelfa ADRD endpoint taxonomy

Results tableno registry results posted yet

Trial facts come from public ClinicalTrials.gov records. Endpoint categories are Delfa's classification of those records, not a ClinicalTrials.gov field. All figures reflect the July 21, 2026 snapshot.