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Australia has recently approved Lecanemab, a groundbreaking drug for the treatment of early-stage Alzheimer’s disease. Marketed under the brand name Leqembi, it represents a significant scientific advancement in tackling the root causes of Alzheimer’s, rather than merely alleviating its symptoms. However, concerns about its cost, accessibility, and safety continue to temper global enthusiasm.

About Lecanemab

• Lecanemab is a monoclonal antibody drug developed by the Japanese pharmaceutical company Eisai, in collaboration with Biogen.
• It belongs to a new generation of Alzheimer’s drugs designed to slow disease progression by targeting amyloid-beta proteins—abnormal clumps in the brain believed to cause neuronal damage and memory loss.
• Unlike traditional Alzheimer’s medications that address symptoms, Lecanemab acts on the underlying pathological process of the disease.
• It is administered intravenously (IV) through a drip, typically on a fortnightly basis for the initial 18 months, followed by monthly maintenance doses.

Mechanism of Action

• Lecanemab works by using lab-engineered antibodies that bind to amyloid-beta plaques in the brain. Once bound, the antibodies trigger the body’s immune system—particularly microglial cells—to clear these toxic protein deposits.
• This helps reduce amyloid build-up, thereby slowing neuronal damage and cognitive decline. Clinical imaging, such as PET scans, has shown significant reductions in amyloid levels among treated patients.

Efficacy and Clinical Evidence

The approval of Lecanemab followed a large phase 3 clinical trial involving 1,734 participants with early-stage Alzheimer’s or mild cognitive impairment.

• Over an 18-month period, patients receiving Lecanemab showed a 27% reduction in disease progression compared to those given a placebo.
• This translated to roughly five months of slower cognitive decline.
• Long-term follow-up data suggest continued benefit for up to four years of treatment.

However, the drug does not reverse existing symptoms, and its benefit is limited to the early stages of the disease.

Safety Concerns and Side Effects

Despite its promise, Lecanemab poses significant safety risks.

• About 12.6% of trial participants developed brain swelling (ARIA-E), while those carrying two copies of the ApoE4 gene—linked to higher Alzheimer’s risk—had a 32.6% incidence.
• 22% of those affected reported symptoms such as headache, dizziness, or vision problems, and a few cases of fatal brain hemorrhage were reported, particularly in patients also taking blood thinners.
• Regular MRI scans every three months are required to monitor these side effects.

Cost and Accessibility

• Lecanemab remains prohibitively expensive, costing around A$40,000 per year in Australia. It is not yet subsidised under the Pharmaceutical Benefits Scheme (PBS), and associated costs such as MRI and PET scans further limit access.
• The Pharmaceutical Benefits Advisory Committee (PBAC) has also raised concerns about whether the modest benefits justify the financial and healthcare burden.

Comparison with Similar Drugs

• Lecanemab follows Donanemab, another monoclonal antibody drug approved earlier in 2024. Both operate on similar mechanisms, with comparable efficacy and risk profiles.
• PBAC previously rejected Donanemab’s inclusion under the PBS, citing uncertain benefits relative to cost and patient safety—concerns that now shadow Lecanemab as well.

Understanding Alzheimer’s Disease

Alzheimer’s disease is a progressive neurodegenerative disorder and the most common cause of dementia, accounting for 60–80% of all cases. It damages brain areas responsible for memory, thinking, and language, leading to cognitive decline and loss of independence.
While age is the main risk factor (most cases occur after 65 years), genetic and environmental influences also play a role.