Drug Update · Neurology

FDA Approves Subcutaneous Lecanemab: CDR‑SB −0.45 in CLARITY AD

July 11, 2026

Drug

Lecanemab (Leqembi; lecanemab-irmb)

Primary efficacy result

CDR‑SB difference -0.45 (95% CI, -0.67 to -0.23) at 18 months vs placebo [1]

Trial

CLARITY AD (phase 3 randomized trial) [1]

Subcutaneous maintenance

360 mg once weekly via LEQEMBI IQLIK autoinjector (label) [11][12]

ARIA (overall)

ARIA observed in 21% of treated patients vs 9% placebo in pivotal dataset [8]

Clinical Perspective

Neurologists and clinicians managing patients with mild cognitive impairment or mild dementia due to Alzheimer’s disease now have an FDA‑cleared subcutaneous maintenance option for lecanemab after an initial period of intravenous dosing, expanding the settings in which maintenance therapy may be administered ^[3]^[4]. The label supports continuing IV 10 mg/kg every 2 weeks for initiation and permits transition after 18 months to either IV 10 mg/kg every 4 weeks or subcutaneous 360 mg weekly via the LEQEMBI IQLIK autoinjector, supported by PK/PD modeling ^[3]^[4]. How best to operationalize ARIA monitoring, genotyping for ApoE ε4 to inform risk, and selection between continued IV versus home subcutaneous maintenance dosing remains an important practical question for care teams?

Dr. Aditi Kulkarni · Neurology

The FDA approved label updates for lecanemab (Leqembi) that add a subcutaneous maintenance option — 360 mg once weekly via the LEQEMBI IQLIK autoinjector — as an alternative to continued intravenous dosing, based on the randomized CLARITY AD trial, which showed an adjusted between-group difference in the Clinical Dementia Rating-Sum of Boxes (CDR‑SB) of -0.45 at 18 months versus placebo (95% CI, -0.67 to -0.23; P<0.001) ^[1]^[4]^[3]. Clinicians should consult current prescribing information for complete dosing guidance.

Clinical Context

Lecanemab (lecanemab-irmb; brand Leqembi) is a humanized IgG1 monoclonal antibody directed to aggregated soluble protofibrils of amyloid-beta and is developed by Eisai and Biogen. The agent was evaluated in early Alzheimer’s disease (mild cognitive impairment or mild dementia) with confirmed amyloid pathology and was previously administered intravenously at 10 mg/kg every 2 weeks in pivotal trials ^[1]^[3]^[4]. Clinicians should consult current prescribing information for full dosing guidance. The FDA label update permits a transition after 18 months of IV dosing either to intravenous 10 mg/kg every 4 weeks or to a subcutaneous maintenance regimen of 360 mg weekly delivered by the LEQEMBI IQLIK autoinjector; the label notes this transition is supported by pharmacokinetic and pharmacodynamic modeling ^[4]^[3]. The clinical questions for neurologists and memory-clinic teams now include implementation of monitoring for amyloid-related imaging abnormalities (ARIA) during and after transition to home subcutaneous dosing ^[2]^[3].

Key Findings

The CLARITY AD phase 3 trial showed that lecanemab reduced decline on the CDR‑SB: adjusted least-squares mean change from baseline at 18 months was 1.21 with lecanemab and 1.66 with placebo (difference, -0.45; 95% CI, -0.67 to -0.23; P<0.001) ^[1].
The trial also demonstrated greater reduction in brain amyloid: a substudy reported a between-group centiloid difference of -59.1 (95% CI, -62.6 to -55.6) favoring lecanemab at prespecified assessments ^[1].
Other prespecified clinical and functional secondary differences in CLARITY AD included ADAS‑Cog14 (-1.44; 95% CI, -2.27 to -0.61), ADCOMS (-0.050; 95% CI, -0.074 to -0.027), and ADCS‑MCI‑ADL (2.0; 95% CI, 1.2 to 2.8) — all favoring lecanemab at 18 months ^[1].
Based on the totality of trial data and modeling, the FDA label now supports continued IV dosing every 4 weeks or a subcutaneous maintenance regimen of 360 mg weekly via the IQLIK autoinjector after a starting period of IV dosing; the label change was reflected in FDA updates in 2026 ^[4]^[3].
Clinicians should consult current prescribing information for full dosing guidance.

Safety & Tolerability

Infusion-related reactions occurred in 26.4% of participants receiving intravenous lecanemab in the phase 3 trial ^[1].
Amyloid-related imaging abnormalities with edema or effusions (ARIA-E) were observed in 12.6% of participants treated with lecanemab in the pivotal trial report ^[1].
In the larger pivotal study population, symptomatic ARIA occurred in 3% (29/898) of lecanemab-treated patients, and serious ARIA-associated symptoms were reported in 0.7% (6/898) ^[2].
Including asymptomatic radiographic events, ARIA was observed in 21% (191/898) of lecanemab-treated patients versus 9% (84/897) on placebo in the pivotal study; ARIA-E occurred in 13% (113/898) versus 2% (15/897), and ARIA-H in 17% (152/898) versus 9% (80/897) ^[2].
ApoE ε4 homozygotes had higher incidence of ARIA on lecanemab (45% on lecanemab vs. 22% on placebo) compared with heterozygotes and noncarriers ^[2].

Study Design

CLARITY AD was an 18‑month, multicenter, double‑blind, phase 3 randomized trial enrolling 1,795 participants 50 to 90 years of age with early Alzheimer’s disease (mild cognitive impairment or mild dementia) and evidence of amyloid pathology; participants were randomly assigned 1:1 to intravenous lecanemab 10 mg/kg every 2 weeks or placebo ^[1]. Clinicians should consult current prescribing information for full dosing guidance. The trial’s primary end point was change from baseline at 18 months in the CDR‑SB; key secondary end points included amyloid PET, ADAS‑Cog14, ADCOMS, and ADCS‑MCI‑ADL ^[1]. The FDA label update permitting subcutaneous 360 mg weekly maintenance after 18 months is supported by pharmacokinetic/pharmacodynamic modeling using observed trial data and was reflected in the 2026 label revisions ^[4]^[3].

FAQ

Q1 What is lecanemab (Leqembi) approved for?

Lecanemab (Leqembi; lecanemab-irmb) is indicated for the treatment of Alzheimer’s disease and should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population studied in the pivotal trials. The label requires confirmation of amyloid pathology prior to initiating treatment and specifies MRI monitoring for amyloid‑related imaging abnormalities during early treatment and at prespecified intervals.

Q2 How does lecanemab work?

Lecanemab is a humanized IgG1 monoclonal antibody that binds with high affinity to aggregated forms of amyloid‑beta, including soluble protofibrils, and reduces brain amyloid burden as measured by amyloid PET; reductions in amyloid were observed in CLARITY AD and in amyloid PET substudies reported in the pivotal publications and labeling.

Q3 What is the recommended dose of lecanemab?

Treatment is initiated with intravenous lecanemab at 10 mg/kg administered after dilution as an intravenous infusion over approximately one hour once every two weeks. After 18 months of starting-dose IV therapy, the label permits continuation of the starting regimen or transition to maintenance dosing: intravenous 10 mg/kg once every 4 weeks or subcutaneous 360 mg once weekly administered using the LEQEMBI IQLIK autoinjector. Confirmatory preparation, administration, and MRI‑monitoring instructions are provided in the full prescribing information. Clinicians should consult current prescribing information for complete dosing guidance.

Q4 What are the most common side effects?

The pivotal trial publications and labeling report infusion‑related reactions (26.4% with IV lecanemab in the trial) and amyloid‑related imaging abnormalities (ARIA) as prominent safety findings. ARIA with edema or effusion and ARIA with hemosiderin deposition (microhemorrhage/superficial siderosis) were observed more frequently than with placebo; symptomatic ARIA occurred in approximately 3% of treated patients in the pivotal dataset, with higher ARIA incidence in ApoE ε4 homozygotes. Rates and management recommendations for ARIA, including MRI monitoring timing and dosing interruption criteria, are detailed in the prescribing information and should guide monitoring and patient counseling.

Clinicians should consult current prescribing information for complete dosing guidance.

FDA Approves Subcutaneous Lecanemab: CDR‑SB −0.45 in CLARITY AD

FDA Approves Subcutaneous Lecanemab: CDR‑SB −0.45 in CLARITY AD

Clinical Perspective

Clinical Context

Key Findings

Safety & Tolerability

Study Design

FAQ

References

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