If a patient has a severe infusion reaction or allergy to lecanemab, can the patient transition to donanemab?

Comment by InpharmD Researcher

There appears to be a lack of evidence specifically assessing whether patients with a severe infusion reaction or allergy to lecanemab can safely transition to donanemab. Existing literature and guidance describe infusion-related reactions with both agents, and one observational study suggests that switching between anti-amyloid therapies may be tolerated in the short term. However, the study did not specifically evaluate patients with prior severe reactions or true hypersensitivity, making the safety and risk of cross-reactivity uncertain.

Background

Available literature describes infusion-related reactions with both lecanemab and donanemab, which are generally most common during early infusions, typically mild to moderate, and managed with symptomatic treatment (e.g., antihistamines, acetaminophen, and corticosteroids for more significant reactions), with discontinuation recommended for grade ≥3 reactions. For patients transitioning between anti-amyloid monoclonal antibodies, guidance is based on pharmacokinetic washout principles and re-initiation of standard dosing in treatment-naïve fashion. Unfortunately, the evidence does not specifically address switching in the context of severe infusion reactions or true hypersensitivity, leaving safety in this setting undefined. [1], [2]

References: [1] Cummings J, Apostolova L, Rabinovici GD, et al. Lecanemab: Appropriate Use Recommendations. J Prev Alzheimers Dis. 2023;10(3):362-377. doi:10.14283/jpad.2023.30
[2] Rabinovici GD, Selkoe DJ, Schindler SE, et al. Donanemab: Appropriate use recommendations. J Prev Alzheimers Dis. 2025;12(5):100150. doi:10.1016/j.tjpad.2025.100150
Literature Review

A search of the published medical literature revealed 1 study investigating the researchable question:

If a patient has a severe infusion reaction or allergy to lecanemab, can the patient transition to donanemab?

Level of evidence

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Please see Table 1 for your response.

Safety of switching from lecanemab to donanemab in 20 consecutive patients with Alzheimer’s disease
Design

Retrospective review

N= 20
Objective To assess the safety of switching from lecanemab to donanemab in patients with Alzheimer's disease, focusing on amyloid-related imaging abnormalities (ARIA) and adverse events
Study Groups All patients (n= 20)
Inclusion Criteria Patients with Alzheimer's disease who switched from lecanemab to donanemab after receiving at least 12 lecanemab infusions
Exclusion Criteria Patients with comorbid neuropsychiatric or cerebrovascular conditions
Methods Retrospective review of 20 patients who switched from lecanemab to donanemab. Patients received at least 12 lecanemab infusions before switching. The average interval between therapies was 3.1 weeks. Cognitive assessment was conducted using Clinical Dementia Rating–Global Score (CDR-GS) and MRI monitoring
Duration Not specified for the entire study, but patients completed at least five donanemab infusions
Outcome Measures Primary: Incidence of new amyloid-related imaging abnormalities (ARIA) and significant adverse events Secondary: Stability of cognitive function as measured by CDR-GS
Baseline Characteristics   All patients (n= 20)
Age, mean years  73 ± 9.6
Body weight, mean kg  58 ± 8.6
Gender - Male 12
Ethnicity - Japanese 17
Ethnicity - Caucasian 1
Ethnicity - Taiwanese 1
Ethnicity - Korean 1
Results   All patients (n= 20)
New ARIA cases 0
Infusion-related reactions (IRRs) 1 (5%)
Cognitive function stability (CDR-GS) No change
Adverse Events No new amyloid-related imaging abnormalities (ARIA) were observed. One patient (5%) experienced an infusion-related reaction (IRR) with donanemab.
Study Author Conclusions Switching from lecanemab to donanemab may not increase the short-term risk of ARIA or IRRs. Prior exposure to lecanemab may reduce ARIA susceptibility during subsequent donanemab therapy. Larger, prospective studies are needed to validate these findings.
Critique The study provides initial insights into the safety of switching between anti-amyloid therapies, but its retrospective design and small sample size limit the generalizability of the findings. The short observation period post-switch may not capture long-term effects or cognitive changes. Additionally, the lack of Apolipoprotein E4 genotyping may affect the understanding of ARIA risk factors. The data are not specific to patients with prior severe infusion reactions or allergy, limiting applicability to that subgroup.
References:
[1] [1] Arai H, Aiba S, Arai R. Safety of switching from lecanemab to donanemab in 20 consecutive patients with Alzheimer's disease. J Alzheimers Dis. 2025;107(2):494-495. doi:10.1177/13872877251361051