Leqembi is a brand-name prescription medication. It’s FDA-approved* to treat Alzheimer’s disease in adults.

Alzheimer’s disease is a condition that affects the brain and cognitive function (the ability to think, communicate, and remember). It’s the most common type of dementia. Alzheimer’s disease is a progressive condition, which means it gets worse over time.

Leqembi treatment may be started in people with Alzheimer’s disease who have mild cognitive impairment or mild dementia. It isn’t known whether the drug is safe or effective if it’s started during earlier or later stages of the disease.

* Leqembi has received accelerated approval from the Food and Drug Administration (FDA). To learn more, see “FDA approval” below.

Drug details

Leqembi contains the active drug lecanemab-irmb. It’s a type of biologic drug called a monoclonal antibody. (The reason “-irmb” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.)

Leqembi belongs to a drug class called amyloid beta-directed antibodies. Amyloid beta is a type of protein. In people with Alzheimer’s disease, this protein builds up and forms deposits called plaques in the brain.

Leqembi comes as a solution inside single-dose vials. It’s given as an intravenous infusion by a healthcare professional.

The drug is available in one strength: 100 milligrams (mg) per milliliter (mL) of solution.

FDA approval

The FDA approved Leqembi in January 2023. It’s important to note that the drug received accelerated approval from the FDA.

Accelerated approval is based on data from early clinical trials of the drug. The FDA’s full approval of Leqembi will be determined after additional clinical trials have been done.

Typically, drugs receive approval from the FDA after undergoing extensive trials. However, for certain types of drugs, such as Leqembi, approval may be granted before all the trials have been completed. Accelerated approval is given for drugs that are used to treat conditions that don’t have many effective treatment options.

Leqembi is used to treat Alzheimer’s disease in adults. It’s a brain condition that’s typically progressive, meaning it gets worse over time. Currently, there aren’t many effective treatment options for people with this condition.

Further, Leqembi’s approval was based on early clinical trials in which the drug was shown to reduce amyloid beta plaques in adults with mild Alzheimer’s disease. (Amyloid beta is a type of protein. In people with Alzheimer’s disease, this protein builds up and forms deposits called plaques in the brain.) However, it isn’t yet known whether the drug reduces the symptoms or slows the progression (worsening) of Alzheimer’s disease.

Effectiveness

For information about the effectiveness of Leqembi, see the “Leqembi uses” section below.

Leqembi is a brand-name drug. There currently isn’t a generic or biosimilar version available.

A biosimilar medication is a drug that’s comparable to a brand-name biologic drug (the parent drug). Leqembi is a biologic medication. Biosimilars are considered just as safe and effective as their parent drug. And like generics, biosimilars tend to cost less than brand-name medications.

Biologic drugs are made from living cells, so it isn’t possible to make exact copies of them. A generic medication, on the other hand, refers to drugs made from chemicals. A generic is an exact copy of the active drug in a brand-name medication.

The Food and Drug Administration (FDA) approves prescription drugs such as Leqembi to treat certain conditions.

Leqembi is a brand-name prescription medication. It’s FDA-approved* to treat Alzheimer’s disease in adults who have mild cognitive impairment or mild dementia.

Leqembi treatment may be started in people with mild Alzheimer’s disease. It isn’t known whether the drug is safe or effective if it’s started during earlier or later stages of the disease.

* Leqembi has received accelerated approval from the FDA. This means the drug has been approved based on data from early clinical trials. The FDA will decide whether to grant full approval of the drug once additional clinical trials have been completed.

Alzheimer’s disease explained

Alzheimer’s disease is a condition that affects the brain and cognitive function (the ability to think, communicate, and remember). It’s the most common type of dementia (cognitive decline). It can affect people of any age but typically affects people ages 65 years and older.

Alzheimer’s disease is a progressive condition. This means the disease causes mild symptoms at first, but the symptoms tend to become more severe over time.

With mild (early stage) Alzheimer’s disease, symptoms may include:

  • trouble with memory
  • confusion
  • wandering away from home or getting lost
  • taking a long time to complete daily activities
  • asking the same questions over and over again

In later stages of the disease, symptoms such as memory loss and cognitive impairment become more severe. Eventually, people with Alzheimer’s disease may no longer recognize their family members and may become dependent on others to take care of them. Behavior changes, such as aggression, can also occur.

The cause of Alzheimer’s disease isn’t fully understood, but it involves changes in the brain. One of these changes is the formation of plaques in the brain. These plaques are caused by a buildup of a protein called amyloid beta.

In clinical trials, Leqembi was shown to reduce amyloid beta plaques in adults with mild Alzheimer’s disease. However, it isn’t yet known whether the drug reduces the symptoms or slows the progression (worsening) of the disease.

To learn more about your condition, visit our dementia hub.

Effectiveness for Alzheimer’s disease

The FDA has approved* Leqembi based on clinical trials in which the drug was shown to reduce amyloid beta plaques in adults with mild Alzheimer’s disease. (Amyloid beta is a type of protein. In people with Alzheimer’s disease, this protein builds up and forms deposits in the brain called plaques.)

However, it isn’t yet known whether the drug reduces the symptoms or slows the progression of Alzheimer’s disease.

* Leqembi has received accelerated approval from the FDA. This means the drug has been approved based on data from early clinical trials. The FDA will decide whether to grant full approval of the drug once additional clinical trials have been completed.

Leqembi and children

Leqembi is not FDA-approved for use in children. Clinical trials of the drug only included adults. The drug is used to treat Alzheimer’s disease, a condition that does not occur in children.

As with all medications, the cost of Leqembi can vary. The actual price you’ll pay depends on your insurance plan, your location, and whether there is a cost for receiving Leqembi infusions.

It’s important to note that your doctor will order Leqembi from a specialty pharmacy. This type of pharmacy carries specialty medications. These are drugs that may be expensive or require help from healthcare professionals to be used safely and effectively. The specialty pharmacy will send the drug directly to your doctor’s office or clinic. (Leqembi is given as an intravenous infusion by a healthcare professional.)

Before approving coverage for Leqembi, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure whether you’ll need to get prior authorization for Leqembi, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Leqembi, or if you need help understanding your insurance coverage, help is available.

A program called the Leqembi Patient Assistance Program is available for Leqembi. For more information and to find out whether you’re eligible for support, call 833-453-7362 or visit the program website.

To learn more about saving money on prescriptions, check out this article.

Biosimilar form

Leqembi is a brand-name drug. There currently isn’t a generic or biosimilar version available.

A biosimilar medication is a drug that’s comparable to a brand-name biologic drug (the parent drug). Leqembi is a biologic medication. Biosimilars are considered to be just as safe and effective as their parent drug. And like generics, biosimilars tend to cost less than brand-name medications.

Biologic drugs are made from living cells, so it isn’t possible to make exact copies of them. A generic medication, on the other hand, refers to drugs made from chemicals. A generic is an exact copy of the active drug in a brand-name medication.

Leqembi can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Leqembi. These lists do not include all possible side effects.

For more information about the possible side effects of Leqembi, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Leqembi, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Leqembi. To learn about other mild side effects, talk with your doctor or pharmacist or view Leqembi’s prescribing information.

Mild side effects of Leqembi can include:

Most of these side effects may go away within a few days to a couple of weeks. However, if they become more severe or don’t go away, talk with your doctor or pharmacist.

* For more information about allergic reaction and Leqembi, see “Allergic reaction” below.

Serious side effects

Serious side effects from Leqembi aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • Amyloid-related imaging abnormalities (ARIA), which are changes that may be seen on an MRI scan of your brain. These changes may involve swelling or bleeding in the brain, which can be life threatening or fatal in rare cases. ARIA doesn’t usually cause symptoms, but some people may experience:
    • headache
    • nausea
    • dizziness
    • confusion
    • changes in vision
  • Severe infusion-related reaction. Symptoms can include:
    • nausea or vomiting
    • trouble breathing
  • Atrial fibrillation (a type of irregular heart rhythm). Symptoms can include:
    • chest pain
    • dizziness
  • Decreased level of lymphocytes (a type of white blood cell).
  • Severe allergic reaction.*

* For details about allergic reaction and Leqembi, see “Allergic reaction” below.

ALLERGIC REACTION

As with most drugs, some people can have an allergic reaction after taking Leqembi. This side effect is possible but wasn’t reported in clinical trials of Leqembi.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Leqembi, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

The cause of Alzheimer’s disease isn’t fully understood, but it involves changes in the brain. One of these changes is the formation of plaques in the brain. These plaques are caused by a buildup of a protein called amyloid beta.

Leqembi contains the active drug lecanemab-irmb.* It’s a type of biologic drug called a monoclonal antibody. Specifically, Leqembi belongs to a drug class called amyloid beta-directed antibodies. It works by targeting amyloid beta proteins and breaking them down to reduce plaques.

In clinical trials, Leqembi was shown to reduce amyloid beta plaques in the brains of adults with mild Alzheimer’s disease. However, it isn’t yet known if the drug reduces the symptoms of the disease. It also isn’t known whether the drug slows the progression (worsening) of Alzheimer’s disease.

How long does it take to work?

It isn’t clear exactly how long it takes for Leqembi to work. To help determine how well Leqembi is working for you, your doctor may use imaging tests, such as a PET scan.

In the drug’s clinical trials, doctors used PET scans to measure the buildup of beta-amyloid protein in the brain. In these trials, Leqembi treatment was shown to reduce plaques in the brains of adults with mild Alzheimer’s disease. These scans were done 53 weeks and 79 weeks after treatment was started.

Your doctor may also use cognitive tests to see if your cognitive function declines while using the drug. They can provide more information on how they’ll monitor whether Leqembi is working for you.

Talk with your doctor if you have questions about what to expect with Leqembi treatment.

* The reason “-irmb” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.

Here are answers to some frequently asked questions about Leqembi.

How does Leqembi compare with Aduhelm?

Clinical trials haven’t been done to directly compare the safety or effectiveness of Leqembi and Aduhelm.

Aduhelm and Leqembi are brand-name drugs prescribed to treat Alzheimer’s disease. Both drugs work in a similar way to reduce plaques (protein buildup) in the brain. It’s thought that reducing plaques may help lessen the symptoms or slow the progression (worsening) of Alzheimer’s disease.

Aduhelm and Leqembi are given as intravenous infusions by a healthcare professional. Aduhelm is typically given once every 4 weeks, while Leqembi is typically given once every 2 weeks.

If you have questions about Leqembi and Aduhelm for Alzheimer’s disease, talk with your doctor.

Can Leqembi cause long-term side effects?

It’s possible, but no known long-term side effects were reported in the drug’s clinical trials. These trials were conducted over a period of 6 to 18 months.

Keep in mind that Leqembi is a new drug. It was approved* by the Food and Drug Administration (FDA) in January 2023. So, limited information is available about the drug’s side effects compared to other drugs that have been on the market for years or decades.

Talk with your doctor if you have questions about Leqembi’s possible long-term side effects.

* Leqembi has received accelerated approval from the FDA. This means the drug has been approved based on data from early clinical trials. The FDA will decide whether to grant full approval of the drug once additional clinical trials have been completed, including data on the long-term safety of Leqembi treatment.

Will Leqembi cure Alzheimer’s disease?

No, there’s currently no known cure for Alzheimer’s disease.

The FDA has approved* Leqembi based on clinical trials in which the drug was shown to reduce amyloid beta plaques in adults with mild Alzheimer’s disease. (Amyloid beta is a type of protein. In people with Alzheimer’s disease, this protein builds up and forms deposits in the brain called plaques.)

However, it isn’t yet known if the drug reduces the symptoms or slows the progression of Alzheimer’s disease.

If you have questions about Leqembi for Alzheimer’s disease, talk with your doctor.

* Leqembi has received accelerated approval from the FDA. This means the drug has been approved based on data from early clinical trials. The FDA will decide whether to grant full approval of the drug once additional clinical trials have been completed.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Leqembi comes as a solution inside single-dose vials. It comes in one strength of 100 milligrams (mg) per milliliter (mL) of solution.

Leqembi vials come in two sizes: 200 mg/2 mL and 500 mg/5 mL.

The drug is prepared and given as an intravenous infusion by a healthcare professional. You’ll receive Leqembi infusions at your doctor’s office or clinic.

Dosage for Alzheimer’s disease

Leqembi’s dosage depends on your body weight in kilograms (kg). One kg is about 2.2 pounds (lb).

The recommended dose of Leqembi is 10 mg per 1 kg. You’ll receive one dose every 2 weeks.

For example, a 110-lb person weighs about 50 kg. If their doctor prescribes 10 mg/kg, their Leqembi dosage would be 500 mg once every 2 weeks.

What if I miss a dose?

If you miss an infusion of Leqembi, call your doctor’s office right away. They’ll help you reschedule to receive your dose as soon as possible.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include noting the appointment on your calendar. You can also ask a caregiver or friend to call you before your appointment to remind you.

Will I need to use this drug long term?

Leqembi is meant to be a long-term treatment. If you and your doctor determine that Leqembi is safe and effective for you, you’ll likely take it long term.

You should take Leqembi according to the instructions your doctor gives you.

You’ll receive Leqembi at your doctor’s office or clinic. Leqembi is given as an intravenous infusion by a healthcare professional. They’ll place a needle into a vein in your arm. Then the drug will flow through a tube connecting an IV bag to the needle and into your body.

It usually takes about an hour to receive a dose of Leqembi. During the infusion, you’ll be monitored by a healthcare professional.

Before you receive your dose of Leqembi, your doctor may give you premedications. These are drugs to help prevent or reduce the side effects of another drug. With Leqembi, premedications may help reduce the risk or severity of infusion-related reactions. Examples of these drugs include:

When to receive

You’ll schedule appointments to receive Leqembi at your doctor’s office or clinic. It’s given as an intravenous infusion once every 2 weeks.

There is no known interaction between Leqembi and alcohol.

However, experts recommend that people with Alzheimer’s disease avoid consuming alcohol. (Leqembi is used to treat Alzheimer’s disease.) This is because drinking alcohol may cause or worsen certain symptoms of Alzheimer’s disease, such as confusion and trouble with memory.

In addition, animal studies suggest that long-term alcohol use may increase the number of amyloid plaques in the brain. So, it’s possible that regular alcohol consumption could make the drug less effective. (Leqembi works by reducing these plaques.) However, the results of animal studies do not always predict what can happen in humans.

If you have questions about drinking alcohol during Leqembi treatment, talk with your doctor or pharmacist.

Leqembi is not known to interact with other medications, herbs, supplements, or foods.

Leqembi is a type of drug called a monoclonal antibody. Based on how this type of drug gets broken down in the body, it should not cause any interactions.

However, this doesn’t mean that interactions won’t be recognized in the future. Before starting Leqembi treatment, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also, tell them about any vitamins, herbs, and supplements you take. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist.

It’s not known if Leqembi is safe for use while pregnant. This drug hasn’t been studied during pregnancy.

If you’re pregnant or planning to become pregnant, talk with your doctor about the potential risks and benefits before starting treatment with Leqembi.

It’s not known if Leqembi is safe to receive during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Leqembi.

For more information about taking Leqembi during pregnancy, see the “Leqembi and pregnancy” section above.

It’s not known if Leqembi is safe for use while breastfeeding a child.

The drug hasn’t been studied in people who are breastfeeding. It also hasn’t been studied in lactating animals.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before starting Leqembi. They may recommend other ways to feed your child.

This drug comes with several precautions. These are considered drug-condition interactions.

Before taking Leqembi, talk with your doctor about your health history. Leqembi may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

Certain APOE genotype

The APOE gene provides instructions for your body to make a protein called apolipoprotein E (ApoE). If you have a certain genotype (version) of this gene called “ε4 homozygous,” you may have an increased risk of swelling or bleeding in the brain. This is also known as amyloid-related imaging abnormalities (ARIA) and is a possible side effect of Leqembi.

A test is available to determine if you have this genotype. Talk with your doctor for more information. They can help you decide if genetic testing is necessary before starting Leqembi. They can also tell you more about how they’ll monitor you for side effects of the drug.

Risk of bleeding in the brain

Leqembi may cause bleeding or swelling in the brain. This is also known as ARIA and is a possible side effect of Leqembi. The drug hasn’t been tested in people who may be at risk for bleeding in the brain.

Examples of risk factors include a history of certain types of stroke or intracranial aneurysm (a bulging blood vessel in the brain). Since Leqembi hasn’t been studied in these situations, it isn’t known if these factors increase the chance of developing this side effect.

For more information, talk with your doctor. They’ll discuss the potential risks and benefits to help determine a safe treatment option for you.

Allergic reaction

If you’ve had an allergic reaction to Leqembi or any of its ingredients, your doctor will likely not prescribe Leqembi. Ask your doctor what other medications may be better options for you.

Pregnancy

It’s not known if Leqembi is safe to receive during pregnancy. For more information, see the “Leqembi and pregnancy” section above.

Breastfeeding

It’s not known if Leqembi is safe to receive while breastfeeding. For more information, see the “Leqembi and breastfeeding” section above.

Note: For more information about the potential negative effects of Leqembi, see the “Leqembi side effects” section above.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.