What to Know About Leqembi, the Alzheimer’s Drug Approved by the FDA

On Thursday, the Food and Drug Administration gave full approval to the drug Leqembi for patients who are in the early stages of Alzheimer’s disease, and Medicare said it would cover 80 percent of the cost of the $26,500-per-year medication. The decisions by the two federal agencies will vastly increase access to the drug but also present a dilemma for patients and their families.

There are many factors, both financial and medical, to weigh. Here are answers to some crucial questions:

How well does the drug work?

Leqembi is not a cure for Alzheimer’s, and the drug doesn’t improve patients’ memories or cognitive abilities. It also does not stop the disease from getting worse. What Leqembi can do is modestly slow down cognitive decline in patients who are in the early stages of the disease. Data from a large clinical trial suggested that the drug may slow decline by about five months over a period of 18 months for those patients.

How the drug might affect a patient’s daily life is likely to vary widely. For some people, Leqembi might mean several additional months of being able to follow a recipe, balance a checkbook or accomplish other activities without help. For others, the impact might be much more subtle and barely noticeable.

Are there risks from taking it?

Yes. The drug can cause swelling or bleeding in the brain that is often mild or moderate and resolves on its own but can be serious and in very rare cases can be fatal. The F.D.A. was so concerned about these side effects that it is requiring a “black-box warning” — the most urgent level — on the drug’s label, saying that the medication can cause “serious and life-threatening events.”

Patients who are at higher risk include those on blood thinners, those who have had more than four microscopic bleeds in the brain and those with an Alzheimer’s-linked gene mutation called APOE4 — especially if they have two copies of the mutation. They, along with their doctors, should consider whether the increased safety risk outweighs their desire for a medication that might modestly slow cognitive decline.

A large clinical trial of the drug found that nearly 13 percent of patients receiving Leqembi experienced brain swelling, but most of those cases were mild or moderate. Less than 2 percent of patients receiving the placebo experienced such swelling. Most brain swelling did not cause any symptoms and generally resolved within a few months.

About 17 percent of the patients receiving Leqembi experienced brain bleeding, compared with 9 percent of patients receiving the placebo. The most common symptom from brain bleeds was dizziness, the study said.

Who is eligible to take Leqembi?

Leqembi — which is administered by intravenous infusions in a doctor’s office or clinic every two weeks — will be available for people diagnosed as having early-stage Alzheimer’s and for those with a pre-Alzheimer’s condition called mild cognitive impairment. About 1.5 million people in the United States fit that description. An additional 5 million who have Alzheimer’s will not qualify for Leqembi because their disease has progressed too far.

The F.D.A.-required label on the drug instructs doctors not to treat patients without testing to confirm that they have one of the hallmarks of Alzheimer’s: a buildup in the brain of the protein amyloid, which Leqembi attacks. Amyloid levels can be assessed with PET scans, spinal taps or newly available blood tests.

How much will we have to pay?

Most patients will be old enough for Medicare, which has said it will pay for 80 percent of the $26,500 annual cost of the drug. Patients would be left with about $6,600 in co-payments, which may put the drug out of financial reach for many. Some or all of that co-payment might be covered by the supplemental private insurance policies that many Medicare patients have.

There are potentially tens of thousands of dollars of additional costs, however — including medical visits for the infusions and regular brain scans. Some Alzheimer’s experts have estimated that the total cost of taking Leqembi could run to about $90,000 a year. With 80 percent coverage, treatment could potentially leave patients saddled with $18,000 per year in out-of-pocket costs.

How should people and their families decide?

Talk to your doctor. If your doctor is not well-versed in Alzheimer’s treatments, consider talking with a specialist. The most important thing is to discuss the decision with medical experts who will carefully explain the risks for your specific situation.

To learn those risks, ask for genetic testing to determine if you have the APOE4 gene mutation. People with two copies of that mutation — about 15 percent of Alzheimer’s patients — are at especially high risk of brain swelling and bleeding.

There are other factors to consider too. Would going to a clinic for a drug infusion every two weeks pose a burden?

And, importantly, how do you and your family perceive your current cognitive condition and how it affects your life? Because Leqembi is for people with mild symptoms, some people might be less inclined to take safety risks, but others might consider it especially important to try a drug that might keep them at this mild stage a bit longer.