Leqembi vs Kisunla: Key Differences
Both Leqembi (lecanemab) and Kisunla (donanemab) are FDA-approved anti-amyloid monoclonal antibodies for early Alzheimer's disease, but they differ significantly in dosing schedule, treatment duration concept, eligibility criteria, and ARIA risk profiles.
Dosing Schedule
Leqembi: 10 mg/kg IV every 2 weeks initially, with option to transition to every 4 weeks after 18 months 1.
Kisunla: Uses a modified titration approach that significantly reduces ARIA risk. The modified titration regimen reduced ARIA-E to 13.7% compared to 23.7% with standard dosing 2. This gradual up-titration maintains comparable amyloid reduction while improving safety 2.
Treatment Duration Philosophy
Leqembi: Continuous therapy model—treatment continues indefinitely at either the initial every-2-week schedule or transitions to maintenance every-4-week dosing after 18 months 1.
Kisunla: Treatment course completion model—patients can be switched to placebo after meeting amyloid-based treatment completion criteria, typically by 52 or 76 weeks, with sustained benefit continuing through 154 weeks 3.
Eligibility Criteria
Leqembi:
- Mild cognitive impairment or mild dementia stage
- Confirmed amyloid pathology
- ApoE4 testing recommended but not required (though patients cannot be risk-stratified without it) 1
- Recent baseline brain MRI required 1
Kisunla (EU-specific, most restrictive):
- Early symptomatic AD
- ApoE4 non-carriers or heterozygotes ONLY (homozygotes excluded from EU indication) 3
- No superficial siderosis at baseline
- No uncontrolled hypertension
- No anticoagulant use 3
The ApoE4 homozygote exclusion for Kisunla in the EU represents a major eligibility difference, as approximately 15% of AD patients are homozygotes 1.
ARIA Risk Profile
ARIA-E Incidence:
Leqembi:
- Overall ARIA-E <10% in phase 2 studies 4
- Real-world data shows 11.2% 5
- Higher risk in ApoE4 homozygotes (2.19 times higher in carriers vs non-carriers) 6
Kisunla:
- Standard dosing: 23.7% at 24 weeks 2
- Modified titration: 13.7% at 24 weeks 2
- Real-world with modified titration: 8.1% (vs 28.6% with original protocol) 5
- EU-eligible population (non-carriers/heterozygotes): 19.5% 3
ARIA-H Risk:
Both agents show increased ARIA-H in ApoE4 carriers (3.45 times higher risk) 6. The risk is particularly elevated in patients with pre-existing microhemorrhages or superficial siderosis 1.
Symptomatic ARIA:
Leqembi: <3% symptomatic ARIA-E cases, generally mild-to-moderate severity 4
Kisunla: Modified titration also reduced ARIA-E severity compared to standard dosing 2
MRI Monitoring Requirements
Leqembi: MRI required at baseline and prior to the 5th, 7th, and 14th infusions 1. This represents monitoring at approximately weeks 8,12, and 26.
Kisunla: Specific FDA-mandated monitoring schedule not detailed in provided evidence, but real-world data shows surveillance MRI captured 95.2% of ARIA events under FDA-approved intervals 5.
Anticoagulation Considerations
Critical caveat: Both agents carry increased hemorrhage risk. The Leqembi Appropriate Use Recommendations specifically state that patients requiring anticoagulants should not receive lecanemab until more data are available 7. Kisunla's EU eligibility explicitly excludes anticoagulant users 3.
Dosing Interruption Protocols
Leqembi has detailed, severity-based suspension criteria 1:
- Asymptomatic mild ARIA-E: May continue dosing
- Asymptomatic moderate/severe ARIA-E: Suspend dosing
- Any symptomatic moderate/severe ARIA-E: Suspend dosing
- Intracerebral hemorrhage >1 cm: Suspend until radiographic stabilization; use clinical judgment whether to resume or permanently discontinue
Real-World Safety Comparison
In a direct within-center comparison, lecanemab and modified-titration donanemab showed comparable safety profiles (all p's >0.40) 5. Both demonstrated ARIA rates matching or better than pivotal trials in a real-world cohort that included patients typically excluded from trials (those with ≥2 chronic comorbidities, autoimmune disorders, concurrent immunomodulators) 5.
Infusion Reactions
Leqembi: 9.0% 5
Kisunla: 12.0% (standard) and 8.0% (EU-eligible population) 5, 3
Key Clinical Decision Points
ApoE4 homozygotes: Can receive Leqembi (with informed consent about higher ARIA risk) but are excluded from Kisunla in the EU 1, 3
Anticoagulation needs: Neither agent is recommended, but this is an absolute contraindication for EU Kisunla eligibility 7, 3
Treatment philosophy preference: Choose Kisunla if treatment course completion appeals; choose Leqembi for continuous therapy model
Baseline MRI findings: >30% of amyloid-positive patients may be excluded due to vascular lesions that increase ARIA risk 8
ARIA risk tolerance: Modified-titration Kisunla may offer lowest ARIA-E rates (8.1% real-world) 5, though Leqembi without titration shows <10% in phase 2 data 4