The Food and Drug Administration (FDA) on Monday approved a new drug for the treatment of Alzheimer’s disease in nearly 20 years. However, the drug — Aducanumab (Monoclonalantibody) — has been opposed by independent advisers saying that the treatment hasn’t been shown to help slow down the brain disease.
According to the Associated Press, “The Food and Drug Administration approved the drug from Biogen based on study results showing it seemed ‘reasonably likely’ to benefit Alzheimer’s patients. It’s the only therapy that U.S. regulators have said can likely treat the underlying disease, rather than manage symptoms like anxiety and insomnia.”
Alzheimer’s disease is a progressive brain disorder that usually appears in individuals who are in their mid-60s. Very rarely, it may occur in individuals younger than 65 years of age, when it is referred to as early onset Alzheimer’s. The disease was first described by Alois Alzheimer in 1906 and manifests itself by disrupting the message carrying neurotransmitters after it destroys brain cells and nerves. A person with Alzheimer’s also loses the ability to perform day-to-day tasks.
Evidence suggests family history, education and chronic conditions like diabetes and heart disease may trigger it.
What does the drug do?
Dr Sahil Kohli, consultant, neurology, Narayana Hospital, Gurugram told indianexpress.com how the drug is a “first therapy” which has shown in research studies to “reduce the Beta Amyloid Plaques in brain, which is the hallmark of the Alzheimer’s dementia”. “As of now, it looks promising. But how much it benefits the patients in clinical practice and what will be the cost of the therapy will get clear in the near future,” he said.
Aducanumab targets amyloid, the underlying cause of Alzheimer’s, explained Dr Vihor Pardasani, neurologist, Bhatia Hospital, Mumbai. “Amyloid is a protein that forms abnormal clumps in the brains of people with Alzheimer’s. These clumps, also called plaques, then damage brain cells and trigger dementia, causing memory and thinking problems, communication issues and confusion,” Dr Pardasani said.
So, why is there opposition?
Scientists are still divided over its potential impact because of uncertainty over the trial results. “An international trial looking at the usefulness of Aducanumab in Alzheimer’s patients was halted prematurely in March 2019 when researchers analysed the interim results and found it not to be useful. Later re-analysis of some data, however, revealed that it might be useful. It must be remembered that FDA has granted this drug approval based on its proven ability to clear amyloid. However, one still needs to complete a clinical trial to confirm that removing the plaque benefits the patients in memory and other cognitive abilities,” said Dr Pardasani.
The logistics of receiving the medication will also be a challenge. “Patients will have to undergo expensive brain scans called Amyloid PET scans (which are currently not freely available in India) to determine eligibility for Aducanumab. Then the drug must be administered monthly via an intravenous infusion which might involve admission for half a day in the hospital,” explained Dr Pardasani.
According to the US-based Alzheimer’s Association, there are over 4 million people in India who suffer from some form of dementia.
While the exact causes of Alzheimer’s is not yet known, the World Alzheimer Report 2018 notes that there is, however, some degree of consensus among scientists that the disease involves two proteins — beta-amyloid and tau. When the former reaches abnormal levels, it forms plaque that deposits itself between neurons, disrupting cell function. Tau too reaches abnormal levels, as a result of which it forms “neurofibrillary” tangles inside neurons, blocking the transport system of neurons. But scientists do not know what causes these proteins to reach abnormal levels in the first place. It is possible that the reasons could be genetic. The report further refers to a Lancet study from 2017, which claimed that lifestyle factors such as diet, physical fitness, smoking, alcohol are related to one-third of Alzheimer’s cases.
Is Alzheimer’s curable now?
At present, both Alzheimer’s disease and most causes of dementia have no cure and as a result, are irreversible. The scientific community is still working towards methods that can slow down the disease’s progression, but do not know how to stop the disease from occurring or stop it’s progression.
“Aducanumab is not a miracle drug nor a cure. It is definitely the first treatment which tackles the mechanism in the brain that drives the destruction of neurons. However, it would only be after further data comes in that its role in Alzheimer’s would become clear,” said Dr Pardasani.