June 8, 2021
The Food and Drug Administration approved the first new Alzheimer’s drug in nearly two decades. The drug, called aducanumab, will be sold as Aduhelm and is given via a monthly infusion at the doctor’s office.
Unlike earlier Alzheimer’s drugs, aducanumab is designed to directly target the underlying disease process in those with Alzheimer’s. Current Alzheimer’s drugs may relieve symptoms like memory loss for a time but do not address the relentless downward spiral of disease. The last drug to be approved for Alzheimer’s was for memantine, brand name Namenda, in 2003.
But experts are divided on whether aducanumab should have been approved at this point. In earlier trials, the drug showed at best mixed results, and some doctors think that more rigorous testing is needed to prove that the drug is effective. An advisory panel who had reviewed the research overwhelmingly recommended against approval of the drug. Biogen, the company that created the drug, itself had doubts about the drug and momentarily halted its development in March 2019.
However, there are still strong hopes that the drug may have benefits for some people with Alzheimer’s disease. It is possible that the weakness of the test results might be explained because only a fraction of the general Alzheimer’s population might respond to the drug, though the sub-population of patients who might benefit has not been clearly identified yet. In ongoing analysis, researchers will be working to better define who might be most likely to benefit from this new treatment.
The FDA granted approval of the drug, but stated that the drug’s manufacturer, Biogen, must begin a new clinical trial to continue assessing its safety and effectiveness.
This treatment not only represents a new option for Alzheimer’s patients, but it also represents a new class of treatment for Alzheimer’s, as it is the first drug known as a monoclonal antibody to be approved for this devastating disease. Because antibodies are related to the immune system, side effects related to the immune system and inflammation will have to be carefully monitored. In some of the earlier trials, the drug caused bleeding or swelling in the brain. It will likely take a few years for that study to be completed.
In the meantime, doctors will be able to prescribe the drug to their patients in the earlier stages of Alzheimer’s disease.
“The data included in the applicant’s submission were highly complex and left residual uncertainties regarding clinical benefit,” said Dr. Patrizio Cavazzoni, the director of the FDA’s Center for Drug Evaluation and Research.
“We feel a great sense of purpose and responsibility to turn the hope of today’s FDA approval of ADUHELM into a reality for people living with Alzheimer’s disease and their families,” said Alisha Alaimo, president of Biogen U.S.
Many patient advocacy groups had urged the FDA to approve the new drug, since there are so few treatments available for Alzheimer’s disease.
The drug is expected to cost up to $56,000 a year; a price has not yet been set. In addition, patients will require periodic MRI brain scans to assess how it is affecting the brain. Infusions of the drug take an hour or so to administer at a doctor’s office or clinic.
The drug targets beta-amyloid, the toxic protein that builds up in the brains of those with Alzheimer’s. According to the amyloid hypothesis, which has been the major theory to address the disease therapeutically over the last few decades, the buildup of this toxic protein leads to the loss of brain cells and memory loss in Alzheimer’s disease. But several promising drugs that target beta-amyloid have shown disappointing results in the past few years. The approval of this new drug will revive the entire amyloid field and boost ongoing clinical trials of other drugs that target beta-amyloid.
Levels of the beta-amyloid protein decrease in people who are taking the drug, but whether that translates to substantial improvements in thinking and memory skills in most patients remains uncertain. This is what the FDA will be focusing on in follow-up testing over the next couple of years.
The drug is designed for people with early Alzheimer’s, since in those with advanced disease, damage to the brain may already be too extensive for the drug to produce benefits. But it will be interesting to see if it can also help people with more advanced disease.