5 Things to Know About the New Alzheimer’s Drug, Kisunla

Reviewed By: Sharyn Rossi, PhD, BrightFocus Foundation 

In July 2024, the Food and Drug Administration approved a new amyloid-clearing Alzheimer’s drug, Kisunla. It’s the second disease-modifying anti-amyloid therapy to receive traditional approval by the FDA. (The first, Leqembi, was approved in 2023.)   

Alzheimer’s researcher and neurology professor at the University of Southern California’s Keck School of Medicine Paul Aisen, MD, joined BrightFocus Foundation’s Zoom In on Dementia & Alzheimer’s virtual discussion series to answer your most pressing questions about Kisunla. Check out his answers below.  

#1: What is Kisunla?   

Dr. Aisen: Kisunla is an effective disease-modifying treatment for Alzheimer's disease. It is actually an antibody that is administered intravenously that attacks amyloid plaques.  

Amyloid plaques are a principal part of the Alzheimer's disease change in the brain. It is the first change that occurs in the disease, the accumulation of this plaque. And amyloid seems to drive the onset of Alzheimer's disease. The body is not able to get rid of amyloid. It's a glue-like substance. It sticks to the brain tissue and can't be cleared.  

The antibody, Kisunla, enters the brain and binds to this substance, to the amyloid, and enables clearance. It allows the body to be more effective in removing amyloid from the brain. Treatment over time with this antibody removes amyloid from the brain, and it's actually quite a dramatic effect.  

We see amyloid using a PET scan. It's a brain scan that can show molecular changes in the brain, and amyloid PET scans show us amyloid. Treatment with this antibody, with Kisunla, removes amyloid and can normalize the PET scan. It's not a subtle effect—it's a draumatic removal of a principal abnormality of Alzheimer's disease. A very exciting development in our ability to address this disease.    

#2: Who is eligible for Kisunla? Who can prescribe it? 

Dr. Aisen: Kisunla and Leqembi have been proven to be effective at a stage of disease that we call early Alzheimer’s disease. Early Alzheimer’s is more specific than just meaning early in the course of disease. It means this—individuals who have a degree of impairment that we, clinicians, call mild cognitive impairment or mild dementia. These are people who have symptoms of difficulty learning new things, difficulty with memory, and difficulty with other aspects of cognitive function. They have some challenges in day-to-day tasks. But the challenges that they have functionally are relatively mild. It is this group of people that have been enrolled in the large definitive trials of Leqembi and Kisunla. And these are the people that are candidates for treatment now. We think that the stage of disease is more important in predicting the benefit than the age. 

Any clinician who can prescribe drugs can prescribe these drugs. However, there needs to be a good understanding of how to use the drugs, how to identify the right people to get the drugs, and how to monitor the treatment so that if there are side effects, they can be managed effectively.  

#3: Will Kisunla be covered by Medicare or insurance? What will it cost? 

Dr. Aisen: The simple answer is yes. Kisunla and Leqembi are covered by insurance and the testing is covered by insurance, because these are full approvals of these two drugs. CMS is the government agency that decides whether Medicaid and Medicare cover a drug. CMS has already decided to approve and pay for a treatment with Leqembi, the drug that was approved last year, and will certainly also cover treatment with Kisunla and the tests necessary to identify who is a candidate for treatment.  

That's a good thing, because they are both expensive. The costs for the drugs themselves are around $30,000 a year. And that's not including the costs of the intravenous infusions, the diagnostic testing, and the monitoring with MRI scans. The costs are quite substantial, but they are being covered and will be covered by Medicare and by insurance.   

#4: What are the risk factors for Kisunla? 

Dr. Aisen: When Leqembi and Kisunla attack amyloid in brain, they essentially bind to the abnormal chemicals in the brain and enable the body's natural defenses to become effective against those abnormal deposits. The abnormal deposits are then cleared by scavenging cells in the brain, and they're cleared through the vasculature, the blood vessels in the brain. As the amyloid moves out, there can be a reaction in the small blood vessels to the removal process. That reaction can cause areas of swelling, and it can cause what we call microhemorrhages, tiny areas of bleeding in the brain.   

How often does this happen? Well, it happens in a significant portion of people who are on these treatments, ranging from about 15% to 25%. In the majority of people who have these effects, they don't know it. The effects just go away, even with continued treatment.  

In some cases, they cause symptoms—the most common is headache. There can be some confusion, unsteadiness, visual symptoms, or neurologic symptoms. Typically, those symptoms just resolve. But in some cases, the symptoms can persist and can become serious.  

In very rare cases, they can become life threatening. The most serious type of reaction is significant bleeding in the brain, and that can be life threatening. How often does that happen? Not often, something like 1 in 1,000. But it is a potential risk.   

One thing I will say is that the risk seems to be greater in people with the Alzheimer’s genetic risk factor, APOE4. The drugs seem to be safer in those people with early Alzheimer’s who don't carry E4. But the benefits outweigh the risks in our view and in the language of the approval in all people with early Alzheimer’s. But, in my opinion, people should consider their genetics when they are evaluating the treatment, because the expected results of this treatment are different depending upon your genetic background. In particular, people with two copies of the E4 gene have a significantly higher risk of side effects from these treatments. So that has to be part of the discussion, part of the consideration of treatment between clinicians and patients and families— what the risk based on APOE is. 

#5: How does Kisunla compare to Leqembi? Can you switch from one Alzheimer’s treatment to the other? 

Dr. Aisen: These two drugs that were both approved in the last year or so represent a huge step forward in Alzheimer's disease therapeutics. They are treatments that are effective at removing one of the principal molecular causes of Alzheimer's disease, the amyloid plaque. That means that they slow disease progression, something that the symptomatic drugs do not do. Symptomatic drugs have no effect on the overall course of Alzheimer's disease.  

Leqembi and Kisunla don't stop progression, but they slow disease progression by 30%. Is that a meaningful slowing? I think it's hugely meaningful. If you want to think about what a 30% slowing means, well, if you were to treat someone for three years, that means saving a year. That means that if you are going to eventually lose the ability, say, to drive a car or to manage your finances down the road, then that would be delayed by a year over the course of three years of treatment.  

What are the differences between Kisunla, the new drug, and Leqembi, the drug that was approved last year? Well, they attack a different part of the amyloid molecule. And that has some implications for how they work.  

• Leqembi has to be administered initially every two weeks intravenously. Kisunla is administered every month intravenously.  

• Kisunla works faster. The removal of the amyloid occurs more quickly with Kisunla than with Leqembi.  

• The side effects appear to be somewhat greater with Kisunla, perhaps related to its faster removal of the amyloid.  

So, these drugs have clear benefits. They also have risks. They need to be used by people who understand these drugs. But that caution aside, it's a major breakthrough and I think really has the potential to improve the lives of millions of people.   

Want to learn more? Watch the full Zoom In on Dementia & Alzheimer’s episode with Dr. Aisen and register for upcoming episodes.   

Responses have been edited for length and clarity.  

Additional Resources: 

• Alzheimer’s Treatments Fact Sheet 
• What’s Next for Alzheimer’s Disease Treatments: A 2024 Forecast 
• (Watch) Alzheimer’s Clinical Trials 2024: The Inside Story with Dr. Jeffrey Cummings 
• Breaking News Dispatch: Alzheimer’s International Conference 

About BrightFocus Foundation           

BrightFocus Foundation is a premier global nonprofit funder of research to defeat Alzheimer’s, macular degeneration, and glaucoma. Through its flagship research programs — Alzheimer’s Disease Research, National Glaucoma Research, and Macular Degeneration Research — the Foundation has awarded nearly $300 million in groundbreaking research funding over the past 51 years and shares the latest research findings, expert information, and resources to empower the millions impacted by these devastating diseases. Learn more at brightfocus.org.    

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