PRIME

TerminatedPhase 1

Multiple Dose Study of Aducanumab (BIIB037) (Recombinant, Fully Human Anti-Aβ IgG1 mAb) in Participants With Prodromal or Mild Alzheimer's Disease

A Randomized, Double-Blinded, Placebo-Controlled Multiple Dose Study to Assess the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of BIIB037 in Subjects With Prodromal or Mild Alzheimer's Disease

Lead sponsor

Biogen

Asset

Aducanumab

Listed sites

Recruiting sites

Enrollment

197

actual

Study population

Alzheimer’s disease

Key I/E criteria

•prodromal AD•Amyloid biomarker required (PET)•MMSE 20-30•Study partner/caregiver required•MRI contraindications excluded

Primary endpoint

•Adverse Events

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

Eudract number2012-000349-10

Org study ID221AD103

NCT IDNCT01677572

Timeline

Milestones

Study first posted2012-09-03estimated

Study start2012-10-05actual

Primary completion2019-07-31actual

Study completion2019-07-31actual

Last update posted2020-08-03actual

Assets

Drug assets

Aducanumab

Study populations

Who this study enrolls

Alzheimer’s disease

Eligibility

Who can enroll

Minimum age50 Years

Maximum age90 Years

SexAll

Healthy volunteersNot accepted

Inclusion criteria

Key Inclusion Criteria:

•Participants must be ambulatory.

•Participants must meet the following core clinical criteria as determined by the Investigator:

Prodromal Alzheimer's Disease (AD) (all of the criteria must apply):

•Mini Mental State Examination (MMSE) scores between 24-30 (inclusive)

•a spontaneous memory complaint

•objective memory loss defined as a free recall score of ≤27 on the Free and Cued Selective Reminding Test (FCSRT)

•a global Clinical Dementia Rating Scale (CDR) score of 0.5

•absence of significant levels of impairment in other cognitive domains

•essentially preserved activities of daily living, and an absence of dementia. OR

Mild Alzheimer's Disease (AD) criteria (all criteria must apply):

•Mini Mental State Examination (MMSE) scores between 20-26 (inclusive)

•a global Clinical Dementia Rating Scale (CDR) of 0.5 or 1.0

•meeting the National Institute on Aging-Alzheimer's Association core clinical criteria for probable AD.

•Participants must have a positive florbetapir positron emission tomography (PET) amyloid scan.

•Participants must consent to apolipoprotein E (ApoE) genotyping.

•Apart from clinical diagnosis of Alzheimer's Disease (AD), participant must be in good health.

•Must have a reliable informant or caregiver

Exclusion criteria

•Any medical or neurological condition (other than Alzheimer's Disease) that might be a contributing cause of the participant's cognitive impairment.

•Have had a stroke or Transient Ischemic Attack (TIA) or unexplained loss of consciousness in the past 1 year.

•Clinically significant psychiatric illness in past 6 months.

•Seizure in the past 3 years.

•Poorly controlled diabetes mellitus.

•History of unstable angina, myocardial infarction, chronic heart failure, or clinical significant conduction abnormalities within 1 year prior to Screening.

•Indication of impaired renal or liver function.

•Have human immunodeficiency virus (HIV) infection.

•Have a significant systematic illness or infection in past 30 days.

•Brain MRI showing evidence of acute or sub-acute micro or macrohemorrhage, greater than 4 microhemorrhages, cortical infarct or greater than one 1 lunar infarct.

•Any contraindications to brain MRI or positron emission tomography (PET) scans.

•Negative positron emission tomography (PET) scan with any amyloid-targeting ligand within 48 weeks of Screening.

•Clinically significant 12-lead electrocardiogram (ECG) abnormalities.

•Alcohol or substance abuse in past 1 year.

•Taking blood thinners (except for aspirin at a prophylactic dose or less)

•Have changes in medications or doses of medication in past 4 weeks.

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

Endpoints (4)

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

Safety / tolerability / PK

Amyloid biomarkers

Other (unclassified)

Amyloid biomarkers

1 endpoint

Secondary/protocol endpoint

Change from baseline in florbetapir-fluorine-18 (18F-AV-45F-AV-45) positron emission tomography (PET) imaging in certain brain areas.

Time frame:Day 1, Weeks 26, 54, End of year 2, 3, and 4

change from baseline, improvement

Safety / tolerability / PK

2 endpoints

Primary/protocol endpoint

Number of Participants with Adverse Events

Time frame:Baseline to week 518

event count, event

Secondary/protocol endpoint

Multiple dose pharmacokinetic (PK) serum concentrations of Aducanumab

Time frame:Up to week 518

concentration, descriptive

Other (unclassified)

1 endpoint

Secondary/protocol endpoint/low confidence

Change from Baseline in Incidence of Anti-Aducanumab Antibodies in Serum.

Time frame:Up to week 518

change from baseline, improvement

Publications (2)

Bibliography

Records linked to this trial through ClinicalTrials.gov references, PubMed NCT search, and curated study seeds. 'Canonical' marks design/result papers; others are registry references or candidates.

Registry references + supporting bibliography

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.