The path to the FDA’s July 15 approval of donanemab was paved with controversy, clinical risk, and a desperate need for answers. Alzheimer’s disease afflicts millions, and for decades, treatment options have been thin. The new drug, developed by Eli Lilly and Company and to be sold as Kisunla, is a monoclonal antibody. It targets the sticky amyloid plaques in the brain that are a hallmark of the disease.
But the approval did not come quietly. Public interest groups spoke out against it during FDA hearings. Their objections were rooted in the clinical trial data itself. That data showed a clear trade-off: a modest slowing of cognitive decline in patients with mild cognitive impairment or mild dementia, against a significant rate of serious side effects.
The most common of those side effects are amyloid-related imaging abnormalities, or ARIA. These are brain hemorrhages and brain swelling. In the clinical trial, 36.8% of people taking donanemab experienced these abnormalities. That is a stark number. In the placebo group, the rate was 14.9%. The consequences can be severe: strokes, seizures, falls, trouble thinking. Headache and allergic reactions were also reported.
This is not a drug for everyone. It is intended only for those in the early stages of the disease. Healthcare providers face a difficult calculus. They must weigh the potential benefit of slowing progression against a real risk of brain injury. Close monitoring for adverse reactions will be essential for every patient prescribed the drug.
The FDA’s advisory panel had its own internal divisions. Most members had concerns. The agency moved forward anyway. The decision reflects the broader landscape of Alzheimer’s research, where every new therapy is scrutinized for how much it helps versus how much it harms. The disease is relentless. Families watch their loved ones fade. The pressure to deliver something—anything—that works is immense.
Donanemab is not the first drug of its kind. It follows aducanumab, another monoclonal antibody that received controversial FDA approval in 2021. That decision also drew sharp criticism from experts who questioned the strength of the evidence. The pattern repeats. A new drug arrives with promise, but the safety data gives pause.
Eli Lilly now has a product on the market. The company will market Kisunla to a population that is desperate and vulnerable. The financial stakes are high. The human stakes are higher. For patients and their families, the approval offers a new option, but it is an option freighted with risk.
The clinical trials that led to this moment enrolled people with mild symptoms. They were the ones most likely to see a benefit. But even in that group, the benefit was limited. The drug does not reverse Alzheimer’s. It does not cure it. It slows the decline. For some, that may be enough to buy precious time. For others, the side effects may outweigh any gain.
The FDA’s approval of donanemab is a landmark. It is also a warning. The drug works, in a narrow sense. But the cost of that work, measured in brain bleeds and swelling, is high. The debate over whether that cost is acceptable will continue. It will play out in doctors’ offices, in ethics committees, and in the lives of patients who must decide whether to take the risk.
