New Alzheimer’s Drug Lecanemab Approved in Australia: What You Need to Know
Dementia is a condition characterized by progressive memory and thinking problems. It is now the most common cause of death in Australia. While there are many causes of dementia, Alzheimer’s disease accounts for about 60% to 80% of all cases.
Last week, Australia’s Therapeutic Goods Administration (TGA) approved a new drug for early Alzheimer’s disease: lecanemab, sold under the brand name Leqembi. This approval follows that of a similar drug, donanemab, earlier this year. Although lecanemab has been shown to slow disease progression in some people diagnosed early, its high cost may put it out of reach for many Australians.
How Does Lecanemab Work?
Lecanemab belongs to a class of drugs known as monoclonal antibodies. When our bodies face foreign invaders such as bacteria or viruses, the immune system produces antibodies—proteins that bind to the invader and mark it for destruction by immune cells.
A monoclonal antibody like lecanemab is produced in a laboratory to target a specific substance—in this case, the amyloid protein. Amyloid plaques are a microscopic hallmark of Alzheimer’s disease. By binding to amyloid, lecanemab helps the immune system to remove this protein from the brain, thereby limiting ongoing damage.
How Effective Is Lecanemab?
The TGA’s approval is based on a large clinical trial involving 1,734 participants over 18 months, funded by Eisai, the drug company. All participants had positron emission tomography (PET) scans confirming the presence of amyloid in their brains before the trial.
Results showed that patients with early Alzheimer’s or mild cognitive impairment due to early Alzheimer’s who received lecanemab experienced 27% less disease progression compared to those given a placebo over 18 months. This was measured using the Clinical Dementia Rating Sum of Boxes scale, which assesses both cognition and function. This slowing of decline equates to about five months less deterioration in those treated with lecanemab.
For patients continuing treatment, evidence suggests benefits may persist for up to four years. Participants also showed substantial reductions in amyloid levels as seen on PET scans. By the end of the trial, most participants were below the threshold indicating Alzheimer’s presence, although their symptoms were not reversed.
What Are the Side Effects?
Safety concerns have been raised by regulators. The TGA initially rejected lecanemab’s approval last year based on its risk-benefit profile. In the clinical trial, 12.6% of patients receiving lecanemab experienced brain swelling. This rate increased to 32.6% in individuals carrying two copies of the apolipoprotein E4 (ApoE4) gene, which promotes Alzheimer’s.
Among those with brain swelling, 22% experienced side effects such as headaches, dizziness, blurred vision, and balance problems. Most side effects were mild. However, a small number of participants on blood-thinning medications suffered serious brain bleeds, some of which were fatal.
The remaining 78% with brain swelling showed no symptoms. Due to these risks, patients on lecanemab require MRI brain scans every three months for monitoring.
Furthermore, 17.3% of patients treated with lecanemab experienced small brain bleeds (microhemorrhages), compared to 9.0% in the placebo group.
Following the initial rejection, the TGA appeal included new safety and efficacy data covering up to four years of treatment.
How Much Does Lecanemab Cost?
Lecanemab is not currently subsidized by Australia’s Pharmaceutical Benefits Scheme (PBS). The drug costs approximately A$40,000 per year, making it unaffordable for many potential patients.
The recommended dosing schedule consists of fortnightly infusions for an 18-month period, followed by monthly maintenance doses. Additional costs include required monitoring such as doctor visits, MRI, and PET scans.
As of now, the Pharmaceutical Benefits Advisory Committee (PBAC) has not yet reviewed lecanemab for PBS listing. The committee recently rejected a similar drug, donanemab, in July due to concerns about limited and uncertain benefits relative to treatment burdens.
Lecanemab and donanemab share similar mechanisms, efficacy, risk profiles, and costs.
Bottom Line
Lecanemab is approved only for early-stage Alzheimer’s disease. If you or a loved one experience early signs—such as consistent short-term memory loss or confusion about dates—it is important to seek medical advice promptly. Early diagnosis is essential to explore available treatment options.
It is important to understand that neither lecanemab nor donanemab cures Alzheimer’s disease. These drugs may slow disease progression but do not improve existing symptoms.
Additionally, lecanemab is not effective for dementia caused by conditions other than Alzheimer’s, nor for individuals with advanced stages of Alzheimer’s disease.
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