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Name: Aducanumab
Synonyms: BIIB037
Therapy Type: Immunotherapy (passive) (timeline)
Target Type: Amyloid-Related (timeline)
Condition(s): Alzheimer's Disease
U.S. FDA Status: Alzheimer's Disease (Phase 1)
Company: Biogen


BIIB037 is a high affinity, fully human IgG1 monoclonal antibody against a conformational epitope found on Aβ. It was originally derived by the biotech company Neurimmune in Schlieren, Switzerland, from healthy, aged donors who were cognitively normal. The rationale was that these donors' immune systems had successfully resisted Alzheimer’s disease and that the operative antibodies could be turned into therapeutics by a process called "reverse translational medicine." BIIB037 binds aggregated forms of Aβ, not monomer. In the brain, BIIB037 preferentially binds parenchymal over vascular amyloid. Thirteen-week chronic dosing in old APP-transgenic mice reduced plaques of all sizes; vascular amyloid stayed unchanged. Brain-exposure studies in mice suggest that microhemorrhages start at 500 mg/kg, more than 100 times the minimally effective dose for plaque clearance, 3 mg/kg (see related conference story). 


A Phase 1 safety and pharmacokinetics study began with a single-ascending-dose trial of 0.3 mg/kg to 30 mg/kg intravenous BIIB037 in 56 people with mild to moderate AD. Participants were assessed at 10 time points up to two years after dosing. Amyloid-related imaging abnormalities (ARIAs) were monitored with four MRI scans, read both locally and by a central reader at an imaging CRO. Side effects included headache, diarrhea, and dizziness. They were mild or moderate, some possibly related to the study drug but not to the dose. No new ARIA developed during the trial beyond age- and AD-related baseline ARIA. In dose-ranging studies, a new dose is given once the safety monitoring board has deemed the previous dose safe. Because BIIB037 seemed safe at 30 mg/kg, 60 mg/kg was added. This amounts to 4 grams in a 150-pound person. (For comparison, the multiple sclerosis antibody natalizumab [Tysabri®] is administered as a 300-mg infusion.) BIIB037 exposure changed in a linear fashion across doses, with little variability from person to person. Consistent with preclinical work, the antibody generated no plasma spike.

In summer 2012, Biogen Idec started PRIME, an ongoing, multiple-dose study in 166 people with prodromal or mild AD, in a multicenter setting. Besides BIIB037, this trial evaluates the performance of proposed research diagnostic criteria (see Dubois et al., 2010; Albert et al., 2011). Prospective participants must score more than 19 on the MMSE, between 0.5 and 1 on the Clinical Dementia Rating, and 27 or lower on the Free and Cued Selective Reminding Test (FCSRT). They then undergo amyloid PET and MRI scans; a positive amyloid scan is required for entry.

Initial enrollment data have been reported. Nineteen imaging centers using 12 different scanner models participate in the BIIB037 prodromal trial and send the scan data to a central reading CRO, where a binary classification method and quantitative standardized uptake value ratios (SUVRs) are compared to establish best methods of interpreting an amyloid scan. Of the first 80 patients scanned, 44 had been diagnosed as prodromal, 36 as mild AD. Of those, the visual read confirmed the clinical diagnosis in 60 percent and the quantitative analysis confirmed the diagnosis in 55 percent of the subjects. The visual read produced no false positives. The false negatives were prodromal cases with a mean MMSE of 27 and an SUVR near the cutoff (see related news story).

In December 2014, Biogen announced its decision to move into Phase 3 based on interim data suggesting target engagement and a cognitive benefit (see Bloomberg news story).On March 20th 2015, an interim analysis of the first data cut pre-specified in the protocol was reported at the AD/PD conference (see Mar 2015 news). Aducanumab dose-dependently reduced amyloid deposition in 6 cortical regions of the brain. The effect was large: after 1 year, the highest dose appeared to have reduced cortical amyloid close to the cutpoint of positivity ARIA-E occurred with increasing dose and ApoE4 genotype; about a third of cases were symptomatic with mild headache and confusion reported in retrospect. Two exploratory signals were reported, as well: aducanumab appears to reduce decline on the MMSE and CDR-SB in dose-dependent fashion. The PRIME study will continue collecting data until 2016. 

To view all clinical trials on BIIB037, see


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News Citations

  1. Safe at 4 Grams? No ARIA at High Dose of Human Aβ Antibody
  2. Biogen Antibody Buoyed by Phase 1 Data and Hungry Investors

Paper Citations

  1. . Revising the definition of Alzheimer's disease: a new lexicon. Lancet Neurol. 2010 Nov;9(11):1118-27. PubMed.
  2. . The diagnosis of mild cognitive impairment due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011 May;7(3):270-9. Epub 2011 Apr 21 PubMed.

External Citations

  1. Bloomberg news story

Further Reading