Lecanemab, marketed by Eisai and Biogen as LEQEMBI, is a humanized IgG1 monoclonal antibody selective for amyloid protofibrils, an intermediate species in amyloid-beta aggregation associated with synaptic dysfunction. The FDA granted accelerated approval in January 2023 and full approval in July 2023 for early Alzheimer's disease. The subcutaneous maintenance-dosing formulation LEQEMBI IQLIK received FDA BLA approval in August 2025. At AAIC 2026 (July 12-15 London), Eisai and Biogen presented additional SC autoinjector data supporting a fully SC treatment pathway from initiation through maintenance, with anti-drug antibody incidence at 1.4% in the 500 mg SC-AI group and no neutralizing antibodies observed.
Real-world outcomes come from the LEADER Study, a multicenter US retrospective analysis of 432 early Alzheimer's patients who received at least seven LEQEMBI infusions as of May 2026. Presented Tuesday July 14 at AAIC 2026, the data show that 75.9% of patients remained clinically stable and 6.6% improved (moving from mild AD dementia to mild cognitive impairment due to AD) over an average of 17 months of treatment. 87% chose to remain on treatment, with results consistent across sex, race, ethnicity, and APOE genotype.
Stories here cover LEQEMBI clinical readouts, commercial and regulatory milestones, and real-world outcome analyses. See [[eisai]], [[biogen]], and [[alzheimers-disease]] for adjacent threads.
Eisai (TSE: 4523) and Biogen (NASDAQ: BIIB) announced Wednesday August 26, 2026 that once-weekly subcutaneous lecanemab-irmb (brand name Leqembi Iqlik) is now commercially available in the United States for initiation therapy in adults with early Alzheimer's disease (AD). Approved patient population: adults with mild cognitive impairment (MCI) or mild dementia due to AD, the same patient population that was approved for the IV formulation. Mechanism: lecanemab is a humanized IgG1 monoclonal antibody targeting soluble amyloid-beta protofibrils and preventing their aggregation into amyloid plaques that drive Alzheimer's pathology. Delivery format shift: the US launch represents the anti-amyloid class's substantive transition from the existing twice-monthly IV infusion format (requiring 1 hour of infusion time plus monitoring) to a weekly subcutaneous injection that substantially improves patient accessibility and reduces the infrastructure burden that has constrained the ongoing global Leqembi launch. Practical impact on Leqembi commercial trajectory: the SC format removes several barriers including infusion center scheduling constraints, long chair time per dose, and IV line placement complications. Eisai and Biogen have been struggling with slower-than-expected Leqembi launch since initial 2023 FDA approval due to reimbursement complexity, MRI monitoring requirements for amyloid-related imaging abnormalities (ARIA), and infrastructure requirements; the SC availability addresses one substantive barrier. Q2 2026 Leqembi worldwide sales reached roughly $340 million; the SC transition is expected to accelerate the commercial trajectory in Q4 2026 and into 2027.
Biogen (NASDAQ: BIIB) reported Q2 2026 earnings before market open Wednesday July 29, 2026 with total revenue of $2.74 billion (+3% year-over-year), GAAP diluted EPS of $0.66, and non-GAAP diluted EPS of $3.60, beating Wall Street consensus. Growth-portfolio drugs (LEQEMBI, SKYCLARYS, SYFOVRE, and EMPAVELI) delivered year-over-year growth and, in aggregate, growth-portfolio revenue exceeded $1 billion for the quarter, surpassing Biogen's legacy multiple sclerosis franchise. Two major pipeline milestones anchored the earnings call: the FDA approved LEQEMBI IQLIK (lecanemab-irmb, a subcutaneous autoinjector formulation) for at-home initiation dosing (following the earlier approval of LEQEMBI IQLIK for maintenance dosing), providing patient-friendly dosing throughout the treatment course; and the Apellis acquisition that closed May 14, 2026 contributed $128 million in combined SYFOVRE (pegcetacoplan intravitreal, for geographic atrophy) and EMPAVELI (pegcetacoplan subcutaneous, for paroxysmal nocturnal hemoglobinuria and C3 glomerulopathy) revenue in the partial quarter. Biogen expects approximately 0.85 EPS dilution from the Apellis acquisition in 2026 with accretion in 2027 and estimated run-rate synergies of at least $250 million exiting 2027. 2026 revenue guidance raised to mid-single-digit growth with non-GAAP EPS guidance of $12-13.
Eisai and Biogen announced Tuesday July 14, 2026 that data from the real-world Lecanemab in Early Alzheimer's Disease (LEADER) Study, presented at AAIC 2026 in London during the Developing Topics Session '#3-33-DEV-A: Lecanemab Three Years Post-Approval: A Comprehensive Multicenter, Real-World, Retrospective Study (LEADER) in Diverse US Clinical Settings,' documented durable clinical outcomes with LEQEMBI in early Alzheimer's disease. The analysis included 432 early Alzheimer's disease patients from diverse US clinical settings who had received at least seven LEQEMBI infusions as of May 2026. Over an average of 17 months of treatment, 75.9% of patients remained clinically stable and 6.6% improved (moving from mild Alzheimer's disease dementia to mild cognitive impairment due to Alzheimer's disease). 87% of patients chose to remain on LEQEMBI treatment. Results were consistent across sex, race, ethnicity, and APOE genotype, supporting long-term benefits of continuous treatment outside of a controlled clinical trial setting.
Eisai and Biogen announced Sunday July 12, 2026 that new clinical data presented at AAIC 2026 in London support that the LEQEMBI (lecanemab) subcutaneous autoinjector (SC-AI) formulation offers efficacy and safety comparable to intravenous (IV) administration in people with early Alzheimer's disease. Data were featured during the Developing Topics Session titled 'Lecanemab Subcutaneous Formulation in Early Alzheimer's Disease: Emerging Clinical Evidence and Practical Use Considerations,' covering the SC formulation, long-term use across diverse patient groups, maintenance dosing, and at-home administration. The findings support a fully subcutaneous treatment pathway from initiation through maintenance treatment, offering greater convenience and flexibility for patients and care partners. The FDA approved Eisai's Biologics License Application (BLA) for subcutaneous maintenance dosing with LEQEMBI IQLIK in August 2025; the SC autoinjector data at AAIC 2026 extends that framework to initial treatment and long-term dosing. Lecanemab is a humanized IgG1 monoclonal antibody selective for amyloid protofibrils; the July 12 dataset is peptide-adjacent to the broader biologic-CNS delivery coverage.
The Alzheimer's Association International Conference (AAIC 2026) opens Sunday July 12 and runs through Wednesday July 15 at the ExCeL London, drawing approximately 12,000 researchers and health-care professionals from around the globe. The peptide-adjacent centerpiece already flagged in Wednesday's Vaccinex announcement is the Featured Research Session on Monday July 13 for pepinemab (humanized IgG4 anti-Semaphorin 4D monoclonal antibody), chaired by Elizabeth Evans, PhD, presenting new glial biomarker data from the Phase 1b/2 SIGNAL-AD study alongside plans for the expanded Phase 2b SIGNAL-AD2 trial. AC Immune (NASDAQ: ACIU) will present three programs from its Morphomer platform: a first-in-class TDP-43 PET tracer with encouraging early human imaging data in frontotemporal dementia and ALS, a novel brain-penetrant NLRP3 inhibitor in Phase 1 that supports an orally delivered CNS therapy profile, and an alpha-synuclein Morphomer showing potent, brain-penetrant inhibition of pathology with neuroprotective effects. Eisai will present 50-plus abstracts spanning the lecanemab (LEQEMBI) Alzheimer's disease portfolio, including biomarker, long-term safety, and clinical-utility readouts.