New Alzheimer’s Drugs Lecanemab and Donanemab: Benefits and Limitations

Leqembi (Lecanemab), a disease-modifying monoclonal antibody therapy, slows cognitive decline in early-stage Alzheimer’s disease by roughly 27% to 33%.

Clinical Efficacy and the Mechanism of Action

Leqembi is designed to target amyloid-beta plaques, a primary pathological hallmark of Alzheimer’s disease. According to findings from the Phase 3 Clarity AD clinical trial, this targeted immunological mechanism alters the underlying pathophysiology of the neurodegenerative process rather than merely masking symptoms.

The clinical benefit translates to a 27% to 33% relative slowing of cognitive and functional decline compared to placebo cohorts. It changes the trajectory of disease progression during its earliest windows.

In Plain English: The Clinical Takeaway

• Disease Modification: Unlike older medications that only treat memory symptoms temporarily, Leqembi targets the root biological cause—amyloid plaque buildup in the brain.
• Target Population: The therapy is strictly indicated for patients with mild cognitive impairment (MCI) or mild dementia due to Alzheimer’s disease, verified via biomarker testing.
• Time Gained: Clinical trials show a delay in cognitive decline.

Global Market Expansion and Regulatory Approvals

The global rollout of disease-modifying therapies (DMTs) has accelerated significantly. The Central Drugs Standard Control Organisation (CDSCO) authorized Leqembi’s introduction in India in August 2026. This launch makes it the first approved disease-modifying therapy for early Alzheimer’s in the region, bringing the drug’s global availability to 53 countries.

Photo: ad-hoc-news.de

Commercial performance reflects growing integration into international neurology workflows. Eisai reported global sales of $554 million for the 2025 fiscal year, followed by $352 million in the first half of 2026. This uptake occurs alongside competing treatments, such as Eli Lilly’s Donanemab (marketed as Kisunla), which demonstrated a 35% slowing of disease progression in Phase 3 trials and recorded $124 million in first-quarter 2026 revenue.

Epidemiological context underscores the urgency driving these market entries. Data from 2023 indicated that approximately 8.8 million individuals aged 60 and older suffered from dementia in India alone, representing a 7.4% prevalence rate. Projections suggest this patient population will double by 2036, mirroring broader demographic aging patterns across global healthcare systems.

Comparison of Anti-Amyloid Disease-Modifying Therapies

Medication	Active Ingredient	Primary Trial Efficacy	Target Pathology
Leqembi	Lecanemab	27%–33% slower cognitive decline	Amyloid-beta plaques
Kisunla / Lormazi	Donanemab	35% slower clinical progression	Amyloid-beta plaques

Contraindications & When to Consult a Doctor

References

• U.S.