Authors' objectives: The Academic Technology Assessment Group (ATAG) reviewed a report submitted by the manufacturer of donanemab (Eli Lilly Japan K.K.) regarding the additional benefits and cost-effectiveness of donanemab for patients with mild cognitive impairment and mild dementia due to Alzheimer's disease. This report summarises the results of a review and reanalysis conducted by the ATAG.For the assessment of Improvements in health outcomes relative to the comparator (additional benefits), the target populations were defined by Mini-Mental State Examination (MMSE) scores: (a) patients with MMSE scores of 22–28 and (b) MMSE scores of 20–21. In target population (a), the comparator was lecanemab plus non-pharmacological therapy with or without donepezil, and in target population (b), the comparator was non-pharmacological therapy with or without donepezil. For target population (a), the manufacturer concluded that additional benefits of donanemab over lecanemab were not demonstrated, because of the comparability of TRAILBLAZER-ALZ 2, a phase III trial of donanemab, and Study 301, a phase III trial of lecanemab due to differences in eligibility criteria, baseline characteristics, efficacy and safety assessments, and treatment duration. For target population (b), the manufacturer reported that donanemab significantly reduced clinical deterioration compared with placebo in terms of the Clinical Dementia Rating-Sum of Boxes (CDR-SB) scores. The decline from baseline to Week 76 in the Integrated Alzheimer's Disease Rating Scale (iADRS) score (primary endpoint) was smaller with donanemab, although the result was not statistically significant. The manufacturer claimed that the results were similar to the overall population, and the additional benefit of donanemab over the comparator has been demonstrated. The ATAG accepted the manufacturer's evaluation for the respective populations. For the cost-effectiveness analysis, the manufacturer used a cost-minimisation analysis for target population (a), and a cost-utility analysis using a Markov model accounting for Alzheimer's disease severity, institutionalization, and mortality for target population (b).The ATAG conducted re-analysis on the efficacy of donanemab, the long-term persistence of treatment effects after discontinuation, caregiver utility weights, and patient proportions. The results of the base-case reanalysis showed that, in the target population (a), donanemab was associated with lower costs than lecanemab, with an incremental cost of -581,004 yen. In target population (b), the incremental cost-effectiveness ratio (ICER) of donanemab compared with the comparator was 17,840,060 yen/QALY from the public healthcare payer's perspective, and 17,228,267 yen/QALY from the public healthcare and long-term care payer's perspective. These results indicate that, for patients with MMSE scores of 22–28, donanemab is likely to reduce costs compared with lecanemab, whereas for patients with MMSE scores of 20–21, the ICER is likely to exceed 10 million yen/QALY.

Project Status: Completed

URL for project: https://c2h.niph.go.jp/en/

Year Published: 2026

URL for published report: https://c2h.niph.go.jp/en/results/C2H2406.html

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: Japan

Organisation Name: Center for Outcomes Research and Economic Evaluation for Health

Contact Address: 2-3-6 Minami, Wako-shi, Saitama 351-0197 Japan

Contact Name: Takeru Shiroiwa

Contact Email: t.shiroiwa@gmail.com