Leqembi (lecanemab) converts to full traditional FDA approval for early Alzheimer's disease
FDA granted traditional approval to lecanemab (Leqembi; Eisai/Biogen) for early Alzheimer's disease — converting the January 2023 accelerated approval. The decision was supported by the phase 3 CLARITY AD trial showing a statistically significant 27% slowing of clinical decline on the CDR-SB scale vs placebo at 18 months. Medicare coverage expanded alongside full approval.
Leqembi (lecanemab) ↗ received accelerated approval from FDA in January 2023 based on reduction of amyloid plaques as a surrogate endpoint. On 2 July 2026, FDA converted this to a traditional approval after the confirmatory phase 3 CLARITY AD trial (NEJM) ↗ demonstrated a statistically and clinically meaningful slowing of cognitive and functional decline — a 27% reduction on the CDR-SB (Clinical Dementia Rating–Sum of Boxes) scale vs placebo at 18 months.
About early Alzheimer's disease
Alzheimer's disease affects an estimated 6.9 million Americans ↗. The "early" stage targeted by lecanemab encompasses mild cognitive impairment (MCI) due to Alzheimer's and mild Alzheimer's dementia with confirmed amyloid pathology (PET or CSF). Lecanemab is a humanised IgG1 monoclonal antibody that targets soluble amyloid-beta protofibrils, facilitating their clearance. Background on the amyloid hypothesis is available via NCBI Alzheimer's disease overview ↗.
Medicare coverage and access
Full traditional approval triggered broader Centers for Medicare & Medicaid Services (CMS) ↗ coverage. Under the CMS National Coverage Determination, Medicare covers lecanemab for beneficiaries who meet the approved indication criteria and are enrolled in a qualifying care programme. Patients must have amyloid confirmed before treatment; the FDA prescribing information ↗ includes monitoring requirements for amyloid-related imaging abnormalities (ARIA), which include ARIA-E (oedema) and ARIA-H (haemosiderin deposits).
Safety: ARIA monitoring
Amyloid-related imaging abnormalities (ARIA) are the most significant safety concern. ARIA occurred in approximately 21% of patients on lecanemab in CLARITY AD vs 9% on placebo; most were asymptomatic and detected on MRI. Serious or symptomatic ARIA requires dose interruption or discontinuation. Carriers of the APOE ε4 allele have higher ARIA risk. MRI monitoring is mandated at baseline and during treatment. Full safety data are available in the DailyMed prescribing information ↗.
FAQ
What does FDA approval mean?
FDA approval means the agency has determined, based on scientific evidence submitted by the manufacturer, that a drug's benefits outweigh its known risks for a specific indication and patient population. The review process includes evaluation of clinical trial data, manufacturing quality, and proposed labelling. See the FDA drug approval process overview ↗.
Does approval mean the drug is available immediately?
Not always. Commercial launch timelines depend on manufacturing scale-up, pricing, and distribution. REMS-restricted drugs ↗ require prescriber or pharmacy enrolment before the product can be dispensed. Rare disease drugs may also have limited initial supply. Check the manufacturer's website or RxNav ↗ for availability status.