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
Rhea-AI Summary
BioArctic (Nasdaq Stockholm: BIOA B) reported that partner Eisai presented interim real-world data from the three-year LEADER study of Leqembi in early Alzheimer's disease at AAIC 2026. Among 427 evaluable patients treated for an average of 17 months (mean 520 days, 26 doses), 82.5% remained stable or improved in disease stage, with 75.9% stable and 6.6% improving from mild AD dementia to MCI due to AD. Results were consistent across sex, race, ethnicity and APOE genotype, and nearly 87% of patients chose to remain on treatment.
In 155 patients on once-every-four-weeks IV maintenance, about 81% were stable or improved, while 12 of 14 on weekly SC maintenance maintained stage. Overall safety was described as consistent with the US FDA-approved label; ARIA occurred in 12.3% of patients, mostly asymptomatic and mild, with no new ARIA-E events, macrohemorrhages or intracerebral hemorrhages >1 cm during IV maintenance.
Positive
- 82.5% of 427 patients stable or improved over ~17 months
- High treatment persistence, with nearly 87% choosing to remain on Leqembi
- IV maintenance cohort showed ~81% stable or improved disease stage
- SC maintenance cohort: 85.7% (12 of 14) maintained disease stage
- Safety described as consistent with US FDA label; no macrohemorrhages >1 cm during IV maintenance
- ARIA incidence among antithrombotic users not meaningfully different from non-users in this cohort
Negative
- Overall 12.3% ARIA incidence; ARIA-E 6.3% and ARIA-H 7.9%
- APOE ε4 homozygotes had 10.3% ARIA-E and 12.1% ARIA-H incidence
News Market Reaction – B
In the Jul 14 session, B gained 1.53%, reflecting a mild positive market reaction.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Historical Context
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Jul 13 | Clinical data presentation | Positive | -2.0% | AAIC 2026 data on Leqembi subcutaneous autoinjector efficacy and safety. |
| Jul 10 | Earnings date announcement | Neutral | -0.4% | Scheduling of Q2 2026 financial results release and webcast details. |
| Jul 02 | Corporate membership update | Neutral | -0.3% | Renewal of corporate membership in an industry talent development group. |
| Jun 30 | Conference presentation preview | Positive | -0.5% | Announcement of extensive lecanemab clinical and real-world data at AAIC 2026. |
| Jun 29 | CFO appointment | Neutral | -1.0% | Appointment of a new chief financial officer at a peer company. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Recent news — including AAIC-related clinical updates and other corporate items — has generally been followed by modest share price declines, regardless of topic.
Key Terms
apoe ε4 medical
intravenous medical
subcutaneous medical
electronic medical record medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
The data were presented during the session "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" at the Alzheimer's Association International Conference® (AAIC®) 2026 in
LEADER study design
The three-year LEADER study is a multicenter, retrospective real-world study designed to examine Leqembi utilization, treatment persistence, transition to maintenance therapy, safety, cognitive and functional assessments, and healthcare professional (HCP) implementation learnings in diverse US clinical settings for patients with early AD. The study integrated deidentified chart and electronic medical record (EMR) data from 13 US sites, HCP surveys and HCP interviews. This interim analysis included 432 patients with early AD who received at least seven Leqembi infusions as of May 2026.
Patient characteristics at baseline:
- Mean age: 74 years
- Female Patients:
55.8%
Disease stage at baseline:
- Mild cognitive impairment (MCI) due to AD:
63.9% - Mild AD dementia:
36.1%
Treatment:
- The mean duration of Leqembi treatment was 520 days
- The mean number of Leqembi doses was 26
- Change in disease stage was defined as:
- Stable: Patient remaining in the same disease stage (MCI due to AD or mild AD dementia) from baseline throughout the course of Leqembi treatment.
- Improvement: Patient transitioning from mild AD dementia at baseline to MCI due to AD over the course of Leqembi treatment.
- Progression: Patient advancing from MCI at baseline to mild/moderate AD dementia or from mild AD dementia at baseline to moderate AD dementia throughout the course of Leqembi treatment.
LEADER study key findings
- Real-world evidence shows long-term benefit with continuous Leqembi treatment across sex, race, ethnicity and APOE genotype
- Real-world safety consistent with US FDA-approved label
Overall study population findings
- Of the 432 participants enrolled in the LEADER Study, disease stage could be evaluated in 427. Among these patients with early Alzheimer's disease,
82.5% remained stable or improved while receiving Leqembi, with consistent results across sex, race, ethnicity, and APOE genotype groups. 75.9% remained stable compared with baseline, meaning they remained in the same disease stage throughout treatment.6.6% improved from baseline, moving from mild AD dementia to MCI due to AD.- Nearly
87% of patients chose to remain on Leqembi treatment. - In analyses by APOE ε4 status, clinician-evaluated stable or improved disease stage was observed in:
-
-
Maintenance Dosing Population Findings
- Of the 432 participants in the LEADER study, 155 transitioned to once-every-four-weeks intravenous (IV) maintenance treatment, and 14 transitioned to once-weekly subcutaneous (SC) maintenance treatment.
- Among the 155 participants who transitioned to IV maintenance therapy, nearly
81% remained stable (72.3% ) or improved (8.4% ). - Of the 14 patients who transitioned to SC maintenance treatment, 12 (
85.7% ) maintained their disease stage.
Overall safety observations in this real-world study were consistent with the US FDA-approved label.
- ARIA[1] was observed in
12.3% of patients overall; ARIA-E was observed in6.3% and ARIA-H in7.9% and isolated ARIA-H in6.0% . Most ARIA cases were asymptomatic and mild in radiographic severity. - No new ARIA-E events, macrohemorrhages or intracerebral hemorrhages greater than 1cm were reported during once-every-four-weeks IV maintenance therapy.
APOE ε4 status safety observations were consistent with the overall cohort and the US FDA-approved label.
- ARIA-E was observed in
5.3% of APOE ε4 noncarriers,6.1% of APOE ε4 heterozygotes and10.3% of APOE ε4 homozygotes. - ARIA-H was observed in
12.1% ,4.8% and12.1% , respectively. - In APOE ε4 homozygotes, no severe ARIA was reported, and all graded ARIA cases were mild to moderate in radiographic severity.
Antithrombotic therapy, including anticoagulants or antiplatelet medications, was used by 106 patients, representing
- Of these, 11 patients were receiving an anticoagulant, either alone or with an antiplatelet medication, and 95 patients were receiving antiplatelet therapy only.
- Among patients receiving antithrombotic therapy, the incidence of ARIA was not meaningfully different from that observed in patients not receiving antithrombotic therapy.
The information was released for public disclosure, through the agency of the contact person below, on July 14, 2026, at 5:15 pm CEST.
For further information, please contact:
Oskar Bosson, Chief Investor Relations & Communications Officer ~
E-mail: oskar.bosson@bioarctic.com
Telephone: +46 704 107 180
Jenny Ljunggren, External Communications and Investor Relations Manager
E-mail: jenny.ljunggren@bioarctic.com
Telephone: +46 76 013 86 08
About Leqembi® (lecanemab)
Leqembi is the result of a strategic research alliance between BioArctic and Eisai. It is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Aβ).
Leqembi is approved in 53 countries and is under regulatory review in 6 countries. Following the initial phase with treatment every two weeks for 18 months, intravenous (IV) maintenance dosing with treatment every four weeks is approved in 8 countries, including the
Since July 2020, Eisai's Phase 3 clinical study (AHEAD 3-45) with lecanemab in individuals with preclinical Alzheimer's disease meaning they are clinically normal and have intermediate or elevated levels of amyloid in their brains, is ongoing. The study was fully recruited in October 2024. AHEAD 3-45 is a four-year study conducted as a public-private partnership between Eisai, Biogen and the Alzheimer's Clinical Trial Consortium that provides the infrastructure for academic clinical trials in Alzheimer's disease and related dementias in the US, funded by the National Institute on Aging, part of the National Institutes of Health. Since January 2022, the Tau NexGen clinical study for Dominantly Inherited Alzheimer's disease (DIAD), that is conducted by Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU), led by Washington University School of Medicine in
About the collaboration between BioArctic and Eisai
Since 2005, BioArctic has a long-term collaboration with Eisai regarding the development and commercialization of drugs for the treatment of Alzheimer's disease. The most important agreements are the Development and Commercialization agreement for the lecanemab antibody, which was signed 2007, and the Development and Commercialization agreement for the antibody lecanemab back-up for Alzheimer's disease, which was signed 2015. In 2014, Eisai and Biogen entered into a joint development and commercialization agreement for lecanemab. Eisai is responsible for the clinical development, application for market approval and commercialization of the products for Alzheimer's disease. BioArctic has the right to commercialize lecanemab in the Nordic region and is currently preparing for commercialization in the Nordics together with Eisai. BioArctic has no development costs for lecanemab in Alzheimer's disease and is entitled to payments in connection with sales milestones as well as royalties on global sales.
About BioArctic AB
BioArctic AB (publ) is a Swedish research-based biopharma company focusing on innovative treatments that can delay or stop the progression of neurodegenerative diseases. The company invented Leqembi® (lecanemab) – the world's first drug proven to slow the progression of the disease and reduce cognitive impairment in early Alzheimer's disease. Leqembi has been developed together with BioArctic's partner Eisai, who are responsible for regulatory interactions and commercialization globally. In addition to Leqembi, BioArctic has a broad research portfolio with antibodies against Parkinson's disease and ALS as well as additional projects against Alzheimer's disease. Several of the projects utilize the company's proprietary BrainTransporter™ technology, which has the potential to actively transport antibodies across the blood-brain barrier to enhance the efficacy of the treatment. BioArctic's B share (BIOA B) is listed on Nasdaq Stockholm Large Cap. For further information, please visit www.bioarctic.com.
[1] ARIA refers to amyloid-related imaging abnormalities that can be observed with anti-amyloid beta antibody treatment and includes ARIA-E, which involves edema/effusion, and ARIA-H, which involves hemosiderin deposition, including cerebral microhemorrhage, cerebral macrohemorrhage and superficial siderosis, as observed on brain magnetic resonance imaging (MRI)
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