All you need to know about 2 new HSA-approved Alzheimer's drugs

Tackling Alzheimer's disease in Singapore received a boost earlier in 2025, when the authorities approved two new drugs for the neurodegenerative disease.

- Zhaki Abdullah

Although these drugs - lecanemab and donanemab - cannot cure or reverse the effects of Alzheimer's, they have been shown to slow the progression of the disease, which accounts for almost 70 per cent of dementia cases worldwide.

Simply Science looks at what these drugs do, how effective they are, as well as the risks and costs.

HOW DO THEY WORK?

The two new drugs are monoclonal antibodies, which are lab-produced proteins that mimic natural antibodies.

They work by targeting and removing beta-amyloids - molecules that accumulate in the frontal cortex and hippocampus of the brain - causing Alzheimer's disease.

Lecanemab, which is marketed as Leqembi, is developed by pharmaceutical firms Eisai, Biogen and BioArctic.

Donanemab, marketed as Lormalzi in Singapore and Kisunla in other countries, is developed by Eli Lilly.

Both are intravenous injections - lecanemab is administered every two weeks over about 1½ years, and donanemab is administered every four weeks over the same period.

HOW EFFECTIVE ARE THEY?

During clinical trials, both drugs demonstrated the ability to slow Alzheimer's disease.

Findings from the clinical trial of lecanemab, published in the New England Journal of Medicine, showed that it slowed decline for people with early Alzheimer's disease by about 27 per cent to 37 per cent.

Meanwhile, results from donanemab's Phase 3 clinical trial, published in the Journal of the American Medical Association, showed that the drug slowed cognitive decline by about 20 per cent to 29 per cent.

Eisai medical director Amitabh Dash said lecanemab differs from existing drugs, which treat symptoms and manage memory or behavioural issues only temporarily.

"It works by clearing these protofibrils and amyloid plaques, which are believed to contribute to the progression of the disease," said Dr Dash.