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Interim analysis of all-case post-marketing surveillance study in Japan: lecanemab in patients with early Alzheimer's disease
Iwata A, Sakata Y, Koizumi K, Endo A, Kuang W, Sumitomo K, Ishii M.. The journal of prevention of Alzheimer's disease, 2026-03-17
Topic: Amyloid, tau and blood-test diagnosis
Background Lecanemab is a monoclonal antibody targeting amyloid-beta protofibrils, indicated for patients with mild cognitive impairment (MCI) and mild dementia due to Alzheimer's disease. Objectives This study reports interim findings of an ongoing, multicenter, prospective, observational post-marketing study for all patients treated with lecanemab in routine clinical practice in Japan, focusing on amyloid-related imaging abnormalities (ARIAs) and infusion-related reactions primarily observed during up to 28 weeks after treatment initiation. Methods Patients treated with lecanemab at any medical institutions across Japan are included in the study. Data are collected using an electronic data capture system via standardized case report forms (CRFs). Study items included the incidence of ARIA, ARIA-edema or effusion (-E), ARIA-hemorrhage (-H: cerebral microhemorrhages, superficial siderosis, and macrohemorrhage), and infusion-related reactions, reported as adverse drug reactions. Results As of July 5, 2025, CRFs from 2675 patients were collected, of whom 2672 had data available for the interim analysis. The median age was 76.0 years, and 62.6 % (1672/2672) of patients were diagnosed with MCI. At Week 28, 7.3 % (195/2672) of patients discontinued treatment, with a mean treatment duration of 189.6 ± 34.4 days. Among 2634 patients confirmed to have undergone MRI scans after treatment initiation, ARIA was observed in 7.1 % (188/2634) of patients, ARIA-E in 3.0 % (78/2634), and ARIA-H in 5.2 % (137/2634). Serious ARIA-H (macrohemorrhage) occurred in two patients (0.1 %). Infusion-related reactions were observed in 17.0 % (455/2672), including 0.7 % (18/2672) serious cases. The proportion of patients who experienced ARIA was highest in patients with apolipoprotein E (APOE) ε4 homozygotes. Conclusion This interim analysis represents one of the largest real-world lecanemab cohorts reported globally to date. Although absolute rates are not directly comparable with those from clinical trials, the trends in ARIA distributions across APOE genotypes and infusion-related reactions were comparable to those observed in clinical trials.
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APA 7th
Iwata, A., Sakata, Y., Koizumi, K., Endo, A., Kuang, W., Sumitomo, K., et al. (2026). Interim analysis of all-case post-marketing surveillance study in Japan: lecanemab in patients with early Alzheimer's disease. The journal of prevention of Alzheimer's disease. https://doi.org/10.1016/j.tjpad.2026.100541
Vancouver
Iwata A, Sakata Y, Koizumi K, Endo A, Kuang W, Sumitomo K, et al. Interim analysis of all-case post-marketing surveillance study in Japan: lecanemab in patients with early Alzheimer's disease. The journal of prevention of Alzheimer's disease. 2026. doi:10.1016/j.tjpad.2026.100541. PMID: 41849958.
BibTeX
@article{iwata2026-41849958,
author = {Iwata, A. and Sakata, Y. and Koizumi, K. and Endo, A. and Kuang, W. and Sumitomo, K. and Ishii, M.},
title = {{Interim analysis of all-case post-marketing surveillance study in Japan: lecanemab in patients with early Alzheimer's disease}},
journal = {The journal of prevention of Alzheimer's disease},
year = {2026},
doi = {10.1016/j.tjpad.2026.100541},
pmid = {41849958},
url = {https://doi.org/10.1016/j.tjpad.2026.100541}
}
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Key findings
- Results As of July 5, 2025, CRFs from 2675 patients were collected, of whom 2672 had data available for the interim analysis.
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Study details
- Study designcase report
- Participants2,675
- Evidence strengthLow
How this study scored 57/100
Published in a peer-reviewed journal. Scored zero for study design, effect reported and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record and institution's track record, so those were left out: it earned 35 of the 61 points we could judge it on, which is 57 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (The journal of prevention of Alzheimer's disease) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | Design recorded as “case report”, which our rubric does not rank (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 3 / 4 | 2,675 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | 2 / 3 | PubMed indexes it as a multicentre study |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41849958) |
| Free to read | 2 / 2 | Free to read |
| Points | 35 / 61 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 35 of the 61 points we could judge it on is 57 out of 100. |
| Total | 57 / 100 | — |
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