Eighteen-month real-world outcomes of lecanemab treatment and transition to maintenance therapy in early Alzheimer’s disease

The 18-month time point is a key milestone in lecanemab treatment, marking completion of the initial treatment course and consideration of transition to maintenance therapy. Real-world data on treatment continuation, discontinuation, and maintenance-transition decisions remain limited. We report a retrospective, single-center cohort of consecutive patients with biomarker-confirmed early Alzheimer’s disease who initiated lecanemab and for whom 18 months had elapsed since treatment initiation. The primary analysis describes treatment status, timing and reasons for discontinuation and transition to maintenance therapy. Cognitive trajectory, cognitive-stage progression and safety were secondary outcomes, MMSE and subgroup analyses were exploratory. The cohort included 84 patients; mean age was 72.0 ± 8.2 years, 47 (56.0%) were female, and 62 (73.8%) had mild cognitive impairment (MCI) at baseline. Six patients (7.1%) continued treatment elsewhere and had unknown maintenance status. Among 78 patients with known status, 43 (55.1%) transitioned to maintenance and 35 (44.9%) discontinued before or at Month 18. Reasons for discountinuation were dementia progression ( n = 13), amyloid-related imaging abnormalities ( n = 8), other medical reasons ( n = 8) and non-medical factors ( n = 6). Estimated MMSE change from baseline was − 1.31, -2.74, and − 2.65 points at 6, 12, and 18 months, respectively. Interpretation was limited by decreasing availability of follow-up assessments and the possibility that missing data were related to clinical course. Amyloid-related imaging abnormalities occurred in 23 patients (27.4%), including edema/effusion in 5 (6.0%). Maintenance transition was not automatic, 44.9% of patients did not continue treatment because of cumulative safety, medical, clinical and non-medical barriers. These findings support ongoing reassessment throughout treatment, with Month 18 serving as a distinct decision point marking the planned transition from the initial biweekly treatment course to longer-term maintenance.