In a landmark decision, the first new medicinal treatment for Alzheimer's disease for 18 years has been approved in the US.
The decision offers hope to the roughly 35 million people living with the disease worldwide if further drug regulators follow suit.
Created by US pharmaceutical company Biogen, Aduhelm targets plaques in the brain that are suspected to be the root cause of Alzheimer’s disease.
This mechanism of action differs from existing treatments which treat the symptoms, and not the cause, of the disease.
“The approval of Aduhelm represents a crucial inflection point in our collective battle against Alzheimer’s disease," said Michel Vounatsos, chief executive officer at Biogen. "By addressing a defining pathology of the disease, this novel therapy has the potential to help fundamentally change the way patients are diagnosed and treated.”
The US drug regulator, the Food and Drug Administration (FDA), granted Aduhelm Accelerated Approval, which is a type of approval process that allows treatments of life-threatening conditions to reach patients quicker than usual, even though more research may be needed to confirm a drug’s actual clinical benefit.
This type of approval is granted for drugs that meet an unmet need and is based on data that shows an effect on something that may predict a clinical benefit, but not necessarily on a clinical benefit itself.
In this case, Aduhelm reduced plaques in the brain which is presumed to decrease the clinical decline of Alzheimer's disease patients over time.
The decision was based on data from two phase III clinical trials, one of which showed a reduction in clinical decline caused by Alzheimer's disease, and one which did not.
However, in both studies overall, the patients given the highest doses of Aduhelm showed a reduction in plaques in the brain.
Some side effects were reported for Aduhelm, including swelling of the brain which occurred in 41% of treated patients compared with 10% in non-treated patients.
The swelling is mostly asymptomatic, but does require regular MRI scans to avoid any potentially hazardous complications.
Regulators in the UK and Europe are currently assessing the data that led to the FDA's momentous decision, but this process will take some time based on Aduhelm's long road to approval.
“Today marks an important turning point for people with Alzheimer’s disease in the US who now have the potential to be prescribed the first ever drug treatment to targets the underlying disease itself," said David Thomas, head of policy at Alzheimer’s Research UK, in a statement.
"The FDA ruling could pave the way for a new generation of drug treatments, but aducanumab still has hurdles to overcome before it could be made available to people in the UK."
The approval has also been shrouded in controversy, with questions raised over its true effectiveness and the moral implications that have been called into question as a result.
"Aducanumab isn't a magic pill that will cure Alzheimer's, so as providers we need to be diligent and thoroughly assess the treatment's rewards and risks with patients," said Dr. Rany Aburashed, chief of neurology at Memorial Healthcare Michigan.
In addition, the studies carried out by Biogen targeted “early mild cognitive impairment and mild cases of Alzheimer’s disease as opposed to more progressive cases”, added Aburashed, which means that patients with more severe disease may not benefit from the therapy.
For the time being, the FDA's approval seems to cover anyone with Alzheimer's disease, with ongoing testing to study effects in different disease severities.
UK and European regulators are expected to announce their response to the approval decision this autumn.
Written by Sarah Nolan
Contributor for Talking Mental Health