An experimental drug for Alzheimer’s disease called aducanumab is being tested after showing positive results in trials. Researchers say aducanumab can slow the progression of symptoms like memory loss and deteriorating focus. What follows is everything we know so far about how it works, the status of drug trials, and when we might know if aducanumab will be available for people with dementia.
Aducanumab is an antibody being studied as a potential drug that eases symptoms of Alzheimer’s disease. Antibodies are made by the immune system to fight viruses and bacteria that make us ill, and drug developers say aducanumab is from cloned immune cells (called “monoclonal antibodies”) that help fight dementia by targeting amyloid beta.
Amyloid beta is a protein that occurs naturally in healthy brains but forms clumps or tangles between the brain cells of people with Alzheimer’s disease, causing brain-cell death that leads to symptoms including memory loss. Studies have suggested that aducanumab binds to amyloid beta tangles and reduces them.
While aducanumab doesn’t reverse or cure the deterioration of the brain as dementia kills cells, aducanumab may be able to slow the loss of memory and general cognition (thinking ability) that are hallmark symptoms of Alzheimer’s disease. Orientation and language problems—like losing track of time and place, and not being able to name well-known objects—also improved in test subjects. The drug’s developer, Biogen, even specifically claimed that test subjects saw an increased ability to manage finances, do chores around the house, go shopping, and leave the home independently. These are instrumental acts of daily living (IADLs) that usually become too difficult for people with dementia somewhere around the middle stages of the disease.
Researchers said a majority of the test subjects taking aducanumab showed no negative side effects. In some cases, however, patients experienced swelling in the brain called “amyloid-related imaging abnormalities” (ARIA) and headache.
Clinical trials are required by the Food and Drug Administration before a pharmaceutical can be approved for use in the public, and aducanumab made it all the way to Phase 3 before an announcement by the drug’s developer, Biogen, that testing had been halted. More than 3,000 patients were part of the trial, but after about 1,700 patients completed 18 months of treatment, Biogen said its researchers determined that statistical modeling (a “futility analysis”) showed the drug wouldn’t work well enough for FDA approval.
When more subjects completed the 18-month treatment, however, and a larger set of data was available, Biogen announced that findings were actually more promising. When assessments of progress in more than 3,000 subjects could be fully analyzed, benchmarks like their scores on the Mini-Mental State Exam (used to measure severity of thinking problems caused by Alzheimer’s) showed improvement compared to those who took a placebo. Also, brain scans showed a reduction in amyloid beta. The FDA approved the resumption of Stage Three trials early in 2020.
Information on the resumption of testing is available here. Unfortunately, test subjects are chosen for the study by invitation only, so participation in trials for aducanumab are not open to the general public.
The FDA has approved new testing for aducanumab, and the developer Biogen has said people who were previously enrolled in the trials will resume being tested to make sure the drug is effective and safe. They will be dosed and assessed for 100 weeks (or almost two years), and so the study isn’t expected to fully conclude until 2023. Trials for FDA approval are always a years-long process, so people hoping for a new Alzheimer’s drug will have a long wait to see if aducanumab can help with their symptoms.