Lecanemab (Leqembi) for early-stage Alzheimer's disease

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Lecanemab (Leqembi) for early-stage Alzheimer's disease

Lecanemab (Leqembi) for mild Alzheimer's dementia

In 2026, the German Institute for Quality and Efficiency in Health Care (IQWiG) last assessed whether lecanemab has advantages or disadvantages compared with cholinesterase inhibitors in adults with mild Alzheimer's dementia who meet the other necessary criteria to be able to have treatment with lecanemab.

The manufacturer provided one study involving just under 1,800 participants. For the assessment, researchers at IQWiG analyzed the data of a relevant subgroup of almost 280 people in this study. All of them were taking cholinesterase inhibitors (donezepil, galantamine or rivastigmine). The people in this subgroup met all of the other necessary criteria to be able to have treatment with lecanemab:

  • They had mild Alzheimer's dementia.
  • Certain protein deposits (amyloid plaques) typical of Alzheimer's disease had been found in their brain.
  • They had only one copy, or no copies, of a specific version of a gene (ApoE4).
  • They were not taking anticoagulants ("blood thinners") at the start of the study.

139 of the people in the subgroup received lecanemab, and 138 of them were given a placebo (a "fake" medication). All of them had treatment with a cholinesterase inhibitor, too. Study participants who had been given memantine were not included in IQWiG's analysis. Memantine has not been approved for the treatment of mild Alzheimer's dementia in Germany and is not part of the standard treatment there.

After 18 months of treatment, the study showed the following:

What are the advantages of lecanemab?

Urinary tract infections (UTIs): The study suggests that lecanemab has an advantage here. This side effect occurred in about 4 out of 100 people who received lecanemab, and in about 12 out of 100 people who did not receive lecanemab.

What are the disadvantages of lecanemab?

Reaction to the infusion: The study suggests that lecanemab has a disadvantage here. With lecanemab, about 23 out of 100 people had symptoms that could be related to the infusion, such as a fever and chills. Without lecanemab, around 7 out of 100 people had these kinds of symptoms.

No difference

Life expectancy: Based on the study data, the researchers deduced that there was no difference in life expectancy between the groups during the 18-month study period.

Severe side effects and stopping treatment due to side effects: About 10 to 14 out of 100 people in each group had severe side effects. In total, around 3 to 7 out of 100 people in the study stopped their treatment because of side effects.

Problems caused by swelling and bleeding in the brain: There was no relevant difference between the groups here. Up to 5 out of 100 people had these kinds of side effects.

There was also no difference between the groups regarding the following aspects. IQWiG concluded this based on the responder analyses provided by the manufacturer. This kind of analysis makes it possible to see how many people's symptoms were noticeably worse after 18 months.

  • Dementia symptoms: The dementia symptoms were noticeably worse in around 27 to 34 out of 100 people, regardless of whether they had received both lecanemab and cholinesterase inhibitors or just cholinesterase inhibitors. The symptoms were assessed using the CDR-SB score.
  • Memory and thinking skills: In each of the groups, the participants' memory and thinking skills became noticeably worse in around 14 to 23 out of 100 people.
  • General health: There was a noticeable decline in overall health in around 16 to 22 out of 100 people, regardless of which treatment they had received.
  • Health-related quality of life: In each of the groups, this became noticeably worse in about 10 to 17 out of 100 people.

What is still not clear?

The manufacturer did not provide any suitable data on the participants' independence in daily life or changes in behavior.

The study did not look at the effects of lecanemab when used alone (monotherapy). Because of this, it is not clear whether lecanemab (on its own, without cholinesterase inhibitors) has any advantages or disadvantages compared to cholinesterase inhibitors (the currently recommended standard treatment) in adults with mild Alzheimer's dementia.

Further information

This information summarizes the main results of reviews produced by the Institute for Quality and Efficiency in Health Care (IQWiG, Germany). The reviews were commissioned by the German Federal Joint Committee (G-BA) as part of the “early benefit assessment of medications.” On the basis of the reviews and the hearings received, the G-BA passed a resolution on the added benefit of lecanemab (Leqembi).

Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Lecanemab (early Alzheimer’s disease) – Benefit assessment according to §35a Social Code Book V. Dossier assessment; Commission A25-111. 2025.

Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Lecanemab (early Alzheimer’s disease) – Addendum to Project A25-111. Commission A26-01. 2026.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Lecanemab (Leqembi) for mild Alzheimer's dementia

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Updated on February 23, 2026

Next planned update: 2029

Publisher:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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