Pharmaceutical giant Eli Lilly’s Alzheimer’s medicine Donanemab — to be marketed as Kisunla — received approval from the United States’ Food and Drug Administration on Tuesday, becoming the third drug in the category to get a nod in three years. These drugs attack the plaques of amyloid beta protein in the brain, clusters of which disrupt brain cell function.

So the drugs have to be administered in the early stages of the disease when the person has mild cognitive impairment or mild dementia.

This clearance is significant because Donanemab is the only drug that has been able to demonstrate that the treatment can be stopped once the protein plaques clear out. “The US Food and Drug Administration has approved Kisunla (Donanemab-azbt) injection for the treatment of Alzheimer’s disease. Kisunla is administered as an intravenous infusion every four weeks,” the FDA said in a statement.

As for India, drug development is important as around 5.3 million people are currently living with dementia and Alzheimer’s is one of the most common forms of dementia. This prevalence is likely to increase to 14 million by 2050.

Why approval took a long time?

The drug had generated much excitement as it slowed cognitive decline in patients in the early stages of the disease. But given that the effects were modest and there were risks such as swelling and bleeding in the brain, the FDA withheld approval in March. It had then said that it would have to undergo the scrutiny of an independent advisory committee. That panel concluded that when it comes to Alzheimer’s, even a modest benefit is worthwhile. The FDA usually goes by the committee’s recommendations.

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The briefing document for the advisory committee on the drug said: “The potential risks of Donanemab, appropriately managed as instructed in labeling, are outweighed by the demonstrated benefits on the clinical endpoints in those with AD.”

Besides, the US congressional committee had found the approval process “rife with irregularities” considering the company’s closeness to the drug panel and cancellation of clinical trials following reports that the drug was unlikely to effectively slow cognitive decline and functional impairment.

Why is such a drug needed?

Dr MV Padma Srivastava, Chairperson of Neurology at Paras Health-Gurugram and former head of department of neurology at AIIMS-Delhi said, “The world is getting older and the burden of diseases such as Alzheimer’s is on the rise. Most countries across the world need drugs such as this, especially in developing countries with huge populations, where the burden is likely to be higher.” She, however, added that the high costs of the drugs have to be factored in while prescribing them to a patient. But she hoped the costs would come down once more companies start manufacturing these drugs.

Are there side effects?

“The prescribing information includes a boxed warning for amyloid-related imaging abnormalities (ARIA),” the FDA said. ARIA or temporary swelling or bleeding in the brain is the most common side effect of medicines with similar mechanisms. Studies have shown that most ARIA events are asymptomatic.

The phase III study of the drug showed that 24 percent of participants given Donanemab had brain swelling and 19.7 percent had brain bleeds. There were also three treatment-related deaths reported in the study.

The phase III study showed that Donanemab had slowed down the cognitive decline in early Alzheimer’s patients by 35.1 percent at 76 weeks. The result was based on a study with 1,736 patients, of whom 860 received the infusion every four weeks until the amyloid beta plaque cleared.