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More than 75% of Leqembi®-treated patients remained stable and nearly 7% improved over an average of 17 months of treatment in real-world LEADER study data presented at AAIC® 2026

BIOA
  • BioArctic AB's partner Eisai presented LEADER study results at the Alzheimer's Association International Conference 2026 in London, showing 82.5% of early Alzheimer's patients remained stable (75.9%) or improved (6.6%) over an average of 17 months of Leqembi treatment.
  • Findings were consistent across sex, race, ethnicity, & APOE genotype groups, supporting long-term benefits of continuous treatment in real-world clinical settings.
  • The three-year retrospective LEADER study analyzed deidentified data from 432 early Alzheimer's patients across 13 US sites who received at least seven Leqembi infusions as of May 2026.
  • Baseline patient characteristics included a mean age of 74 years, 55.8% female patients, 63.9% with mild cognitive impairment due to AD, & 36.1% with mild AD dementia.
  • Treatment duration averaged 520 days with a mean of 26 doses, & nearly 87% of patients chose to remain on Leqembi.
  • Among APOE ε4 heterozygotes, 81.7% remained stable or improved, while 81.0% of APOE ε4 homozygotes showed similar outcomes.
  • Of 432 participants, 155 transitioned to once-every-four-weeks intravenous maintenance therapy (81% stable or improved) & 14 transitioned to once-weekly subcutaneous maintenance therapy (85.7% maintained disease stage).
  • Safety profiles remained consistent with the US FDA-approved label, with amyloid-related imaging abnormalities (ARIA) observed in 12.3% of patients overall.
  • ARIA-E occurred in 6.3% of patients & ARIA-H in 7.9%, with most cases being asymptomatic & mild in radiographic severity.
  • No new severe ARIA-E events, macrohemorrhages, or intracerebral hemorrhages greater than 1cm were reported during once-every-four-weeks intravenous maintenance therapy.
  • ARIA-E rates varied by APOE ε4 status: 5.3% in noncarriers, 6.1% in heterozygotes, & 10.3% in homozygotes, with all ARIA cases in homozygotes graded as mild to moderate.
  • Antithrombotic therapy was used by 24.5% of the study population, & the incidence of ARIA in this group was not meaningfully different from patients not receiving such therapy.
  • Leqembi is approved in 53 countries, with subcutaneous formulations approved in the US for starting & maintenance doses, & regulatory applications pending in additional regions.
  • BioArctic & Eisai maintain a long-term collaboration where Eisai handles global development & commercialization, while BioArctic retains commercialization rights in the Nordic region.