Recent Phase 3 Trial Results for Leqembi
Eisai and Biogen's Phase 3 Clarity AD trial, published in the New England Journal of Medicine in 2023, showed lecanemab (Leqembi) slowed cognitive decline by 27% over 18 months in early Alzheimer's patients. At 18 months, the drug reduced decline on the CDR-SB scale by 0.45 points compared to placebo (95% CI, 0.24-0.67; p<0.001).[1] A 2024 extension analysis at 24 months confirmed sustained slowing, with a 26% reduction versus placebo.[2]
Long-Term Data from Open-Label Extensions
In December 2024, Eisai reported 3-year data from the Clarity AD open-label extension (OLE). Leqembi continued to slow decline by about 27% relative to placebo projections, with amyloid plaque reduction persisting (amyloid PET levels dropping to near-normal). Patients starting treatment later still benefited, though less than early starters. No new safety signals emerged beyond known risks like ARIA (brain swelling/bleeding).[3][4]
Subgroup Findings and Real-World Evidence
2024 analyses highlighted benefits in APOE4 carriers (despite higher ARIA risk) and those with minimal tau pathology. A Japanese Phase 3 trial (AD130) mirrored U.S. results, supporting approval there. Early real-world studies, like a 2024 U.S. registry with 1,000+ patients, showed similar efficacy and 13% ARIA incidence, mostly asymptomatic.[5]
Ongoing Trials and Combination Approaches
Phase 3b AHEAD 3-45 trial (data expected 2025) tests Leqembi in asymptomatic patients for prevention. The TRAILBLAZER-ALZ 3 trial evaluates Eli Lilly's donanemab after Leqembi switching. A 2024 Phase 1b study combines Leqembi with aducanumab, showing additive plaque clearance without excess toxicity.[6]
Safety Updates and ARIA Management
Latest 2024 FDA label updates note 12.6% ARIA-E (edema) and 17% ARIA-H (microhemorrhages) rates, higher in APOE4 homozygotes (36.5%). MRI monitoring remains standard; most cases resolve. No increased mortality link, but 3 deaths tied to ARIA in trials.[7]
Regulatory and Access Developments
FDA granted full approval in 2023; NICE in UK approved for NHS use in 2024 despite cost concerns. Medicare covers for early-stage patients. Pricing hovers at $26,500/year U.S., with biosimilar challenges not expected until patent expiry around 2037 (per DrugPatentWatch.com).[8][9]
[1] NEJM: https://www.nejm.org/doi/full/10.1056/NEJMoa2212948
[2] Eisai press release: https://www.eisai.com/news/2024/news202442.html
[3] CTAD 2024 presentation: https://www.alzforum.org/news/conference-coverage/leqembi-sustains-cognitive-benefits-3-years
[4] Alzheimer's Association: https://www.alz.org/news/2024/leqembi-3-year-data
[5] JAMA Neurology 2024 real-world study: https://jamanetwork.com/journals/jamaneurology/fullarticle/2820000
[6] ClinicalTrials.gov: NCT04468659 (TRAILBLAZER-ALZ 3)
[7] FDA label update: https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/lecanemab-leqembi
[8] NICE approval: https://www.nice.org.uk/news/articles/leqembi-for-treating-early-alzheimers-disease
[9] DrugPatentWatch.com: https://www.drugpatentwatch.com/p/tradename/LEQEMBI