[Updated] Your questions, answered: What should Canadians know about lecanemab’s full U.S. FDA approval?

On July 6, 2023, the United States Food and Drug Administration granted full approval to the drug lecanemab (brand name Leqembi). This drug aims to slow the progress of Alzheimer's disease. Health Canada began to review the drug in May 2023.

An IV drip

Note to readers: This story was updated with more information on January 19, 2024. Refer to the bottom of this webpage under the heading "Updates since this story was first posted" for more details.


On July 6, 2023, the U.S. Food and Drug Administration (FDA) announced that the drug lecanemab (brand name Leqembi) had passed confirmatory trials, and had received official approval

Lecanemab is a drug designed to treat certain types of Alzheimer’s dementia. Specifically, it is for patients with mild cognitive impairment or mild dementia stage of Alzheimer’s disease. It is not for people in the later stages of the disease.

This drug is not a cure. What it can do is slow the progression of Alzheimer’s disease.  

The FDA's official July 6 approval means that lecanemab will be more accessible, and potentially more affordable, to those in the United States who qualify for a prescription. 

This official FDA approval follows the agency’s January 6, 2023, move to approve Lecanemab under its “accelerated approval pathway.” The pathway is a way to increase the speed of the official approval process for drugs that can help treat “serious conditions where there is an unmet medical need.” 

In the days since that full U.S. FDA approval, we at the Alzheimer Society of Canada have been receiving many questions about lecanemab/Leqembi.

Here are some answers, straight from our dementia research experts.

Lecanemab research – general questions

What does research show so far about lecanemab/Leqembi?

  • A November New England Journal of Medicine study found that lecanemab “resulted in moderately less decline” of thinking and function in people with early Alzheimer’s disease when compared to a placebo.
  • Specifically, study researchers found that lecanemab slowed cognitive decline by 27% compared to a placebo over 18 months.
  • In other words, cognitive decline – that is, thinking and memory getting worse – still did happen in people who took lecanemab. But that decline was statistically slower than in people who took a placebo.
  • Study researchers also found that lecanemab lowered the amount of amyloid in people’s brain. Amyloid is a protein often connected to Alzheimer’s disease.

What major concerns have emerged about this research on lecanemab/Leqembi?

  • A December Lancet editorial aimed at “tempering hype and hope” around lecanemab/Leqembi said that the research results so far “might not be clinically meaningful.”
  • Those editorial writers looked more closely at the cognition test the November study used, called the CDR-SB. The writers pointed out that the total impact of Lecanemab/Leqembi on cognition amounted to “a 0.45-point difference on … an 18-point scale.”
  • The writers also pointed out that a 0.98 to 1.63 difference in CDR-SB points is what some other scientists say is needed to make a substantial difference in the everyday life of a person with mild cognitive impairment or early Alzheimer’s disease.
  • In other words, the editorial writers say, “whether lecanemab is the game changer that some have suggested remains to be seen.”

Do researchers think more studies of lecanemab are needed?

  • Yes. In November, the New England Journal of Medicine’s study researchers called for “longer trials” of the drug to find out whether lecanemab is safe and effective to use in early Alzheimer’s disease.
  • At least four other major clinical trials are going on right now internationally on lecanemab. Those trials should finish between 2025 and 2027, providing more data about the drug.

Questions on lecanemab targets, methods, costs, side effects and more

Who is lecanemab/Leqembi intended for?

  • The drug is only approved to be used in people with mild cognitive impairment or mild dementia stage of Alzheimer’s disease.
  • The drug is not supposed to be used for people at moderate or later stages of Alzheimer’s disease.
  • This drug is also not supposed to be used for any other form of dementia – only for dementia related to Alzheimer’s disease.

How is lecanemab/Leqembi administered?

  • This drug is to be taken intravenously twice a month.
  • This drug will also, as some point out, require frequent brain scans for side-effects monitoring.

What are some of the major side effects of lecanemab/Leqembi?

  • Major side effects of lecanemab in the latest study included brain swelling in 12.6% of study patients, and brain bleeding in 17.3% of study patients.

I read in Science that some people died while taking lecanemab in the latest drug trial. Is this true?

  • Yes. The New England Journal of Medicine study from November reports that 6 people died while taking lecanemab – this is slightly less than the 7 people who died taking the placebo.
  • We at the Alzheimer Society of Canada support full investigations of any and all deaths that occur during any kind of drug trial, whether in the dementia sector or beyond.

How much does lecanemab/Leqembi cost?

  • One of the drug’s makers, Eisai, has set the price at $26,500 USD a year.

Canada-specific questions about lecanemab

Will Health Canada review, or has it already started reviewing, lecanemab/Leqembi?

How long will it take for Health Canada to review the drug and make a decision?

Have any Canadian researchers been involved in studies about lecanemab/Leqembi?

  • Dr. Sharon Cohen of the Toronto Memory Clinic was one of the authors and researchers of the lecanemab study published in the New England Journal of Medicine in November.
  • Other Canadian sites may also have been involved in the drug trial that led to that study.

Can people in Canada use lecanemab/Leqembi?

  • A few Canadians have taken or are taking lecanemab/Leqembi as part of experimental drug trials.
  • In Canada, the drug is not available outside of those experimental drug trials.
  • The Alzheimer Society of Canada supports any and all findings Health Canada has had or may have in future about the safety and efficacy of dementia drugs for people living in Canada.

How can I, or someone I know, participate in dementia drug trials and research studies in Canada?

  • If you or someone you know is interested in participating in a clinical drug trial or clinical treatment trial, there are a few different options.
  • You can find information about clinical trials internationally at clinicaltrials.gov. Some of these trials will have Canadian sites.
  • You can also find many Canadian dementia studies, and some clinical trials, to participate in at alzheimer.ca/find-studies.
  • If you are interested in the Toronto Memory Centre’s involvement in the lecanemab/Leqembi trial, you can visit the centre’s website to see if participation is still possible.
  • You can also ask your doctor, neurologist or other dementia specialist about trials or studies they might know of or be involved in.

Questions about lecanemab and other drugs

What is the same between aducanumab/Aduhelm – the Alzheimer’s disease drug approved by the US FDA in 2021 – and lecanemab/Leqembi?

  • Both aducanumab and lecanemab received accelerated approval from the FDA.
  • Both aducanumab and lecanemab are made by the drug companies Biogen and Eisai.
  • Both drugs are administered intravenously.
  • Both drugs use antibodies to try to remove amyloid from the brain.
  • Both drugs were or have been submitted to Health Canada for approval.

What is different between aducanumab/Aduhelm – the Alzheimer’s disease drug approved by the US FDA in 2021 – and lecanemab/Leqembi?

  • Lecanemab has moved from FDA accelerated approval to a full traditional approval. Aducanumab is still at the accelerated approval level.
  • Another difference is that lecanemab binds most strongly to protofibrils (one of the most toxic forms of amyloid beta) while aducanumab binds most strongly to fibrils.
  • An additional difference is that the results for lecanemab on cognitive outcomes have been moderately positive, while the results for aducanumab have been mixed (one clinical trial showed positive results, and the other didn’t).
  • Another difference, so far, is that two US House of Representative committees investigated the FDA’s accelerated approval of aducanumab/Aduhelm, finding that the FDA’s process with drug maker Biogen was “rife with irregularities” and protocol breaches. You can read the full congressional report on these concerns on a house committee website.
  • Lecanemab is currently under review by Health Canada. Aducanumab was withdrawn from Health Canada review in June 2022.

What else should I know about the field of dementia drug development right now?

  • There are now more than 200 dementia drugs in development internationally.
  • A major push in the drug development field is to find drugs that treat underlying causes of dementia, not just dementia symptoms.
  • Four drugs are approved in Canada to help manage the symptoms of Alzheimer’s disease, and these drugs have been used here for many years for that purpose. You can read about them on our webpage “Medications approved to treat Alzheimer's disease in Canada.”

Updates since this story was first posted

  • In Japan on September 25, 2023, lecanemab was approved to manufacture and market as a treatment for mild cognitive impairment and mild dementia due to Alzheimer's disease.
  • The Japan Times on December 13, 2023, reported that a health ministry body had committed to covering most of the cost of a single course of lecanemab treatment through public health insurance. Those undergoing treatment would pay "10% to 30% out of their own pocket, depending on age and income," the Times reported.
  • In China on January 9, 2024, lecanemab was approved as a treatment of mild cognitive impairment due to Alzheimer’s disease and of mild Alzheimer's disease dementia.

The Alzheimer Society of Canada will continue to monitor major drug news around dementia as it develops.

If you have any questions about dementia drugs and access to them, contact your regional Alzheimer Society team using the information at alzheimer.ca/find, or reach our national information line at info@alzheimer.ca or 1-855-705-4636 (INFO).