January 15, 2020
The drug company Biogen is seeking approval for an experimental drug called aducanumab for treating people in the early stages of Alzheimer’s disease.
The announcement was surprising, since the company had stopped trials of the drug in the spring after it announced that studies did not show significant benefits. Many patients who had entered the experimental study showed great disappointment about having to stop taking the drug, which works in an innovative way to slow progression of Alzheimer’s disease. Currently available drugs for Alzheimer’s may ease symptoms for a time but do nothing to stop the relentless progression of disease.
But a reanalysis of the data this fall showed that aducanumab might have benefits in slowing the progression of Alzheimer’s disease. After 18 months, those taking the drug had 15 percent to 27 percent less decline in memory and thinking skills compared to those taking a placebo pill. Those getting the highest doses of the drug showed the most benefit.
The company is seeking drug approval from the Food and Drug Administration to treat early Alzheimer’s or mild cognitive impairment, a memory-impairing brain disorder that often precedes Alzheimer’s. The drug does not, however, cure or prevent Alzheimer’s. The company is saying only that it may slow progression of the disease in certain people.
If approved, the drug would be the first new drug specifically for Alzheimer’s disease in over a decade, and the first drug to actively target the cause of the disease rather than just the symptoms. It is unknown if or when approval might come.
Aducanumab is what is known as a monoclonal antibody drug and is given as a monthly infusion into the blood stream..It targets beta-amyloid, a toxic component that builds up in the brains of those with Alzheimer’s disease. Researchers had hoped that reducing the amount of beta amyloid and consequently preventing the buildup of beta-amyloid aggregates that form plaques might halt the loss of brain cells.
As with dozens of other experimental drugs, early, small-scale studies of aducanumab suggested it might have benefits in slowing cognitive decline, and it appeared to be generally safe. But as with those drugs, late-stage testing in large numbers of people had disappointing results, leading drug manufacturers to abandon them.
The fact that Biogen is reviving interest in the drug is bringing new hope for better treatments for Alzheimer’s. Evidence suggests that brain changes in Alzheimer’s typically begin years prior to the memory loss and other symptoms that lead to a clinical diagnosis, and researchers hope that administering drugs at the earliest stages might produce the best results. It is also plausible that this treatment, as well as other drugs that have been tested and failed on large groups of patients, might only work in a sub-population of patients — a sub-population that we don’t know yet how to define.
New basic research is needed to understand what causes Alzheimer’s disease, and how it might be treated or prevented, or its progression slowed. A number of drug companies are continuing to test dozens of experimental drugs that look at various possible mechanisms for the disease, including inflammation, the immune system, various infections and a brain substance called tau. Other drugs that target beta-amyloid are also undergoing testing.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Biogen, October 2019.