BioArctic AB's (publ) presented new data on the investigational subcutaneous formulation of LEQEMBI showing that it clears 14% more amyloid plaques as measured by PET compared to intravenous infusion (IV), with pharmacokinetics (AUC) 11% higher and similar ARIA rates. An additional analysis of the phase 3 Clarity AD data for LEQEMBI in the PET low tau population revealed that 76% of patients in the low tau population showed no decline and 60% showed clinical improvement at 18 months of treatment. The data was presented in the Late Breaking Symposium 4 "Lecanemab for Early Alzheimer's Disease: Long-Term Outcomes, Predictive Biomarkers and Novel Subcutaneous Administration" at the 16th annual Clinical Trials on Alzheimer's Disease (CTAD) conference held in Boston, Massachusetts, United States and virtually October 24-27, 2023.

Eisai aims to submit a LEQEMBI subcutaneous formulation Biologics License Application (BLA) with the U.S. Food and Drug Administration by March 31, 2024. Subcutaneous formulation interim data; safety and effects on brain amyloid. However, due to the sample size of newly treated patients in the SC substudy, no exact comparison can be made.

Based on Phase II and III clinical studies, Cmax (maximum exposure) was the strongest predictor of ARIA-E incidence following IV administration. In the SC substudy, the steady-state exposure (AUCss) appears to be a better predictor of ARIA-E rates in the SC due to a relatively stable exposure profile. Importantly, in this low-tau subgroup, LEQEMBI treatment also showed consistent clinical response across multiple endpoints.

In the population studied with tau PET, LEQEMBI treatment favored cognition and function in the earlier stage of early AD. The efficacy results of the tau PET substudy in the Clarity AD study, were consistent with overall results of the Clarity AD study. b. Tau PET substudy showed LEQEMBI slows development of tau tangles in early AD; Tau spread in the brain is a hallmark of disease progression.

This release discusses investigational uses of an agent in development and is not intended to convey conclusions about efficacy or safety. There is no guarantee that such investigational agents will successfully complete clinical development or gain health authority approval. Lecanemab is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Ab).

In the U.S., LEQEMBI was granted traditional approval by the US Food and Drug Administration (FDA) on July 6, 2023. LEQEMBI is an amyloid beta-directed antibody indicated as a disease-modifying treatment for Alzheimer's disease (AD) in the US. Treatment with LEQEMBI should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials.

In Japan, Eisai received approval from the Ministry of Health, Labour and Welfare (MHLW) on September 25, 2023, to manufacture and market lecanemab as a treatment for slowing progression of MCI and mild dementia due to AD. In China and Israel, the applications have been designated for priority review, and in Great Britain, lecanemab has been designated for the Innovative Licensing and Access Pathway (ILAP), which aims to reduce the time to market for innovative medicines. Eisai has completed a lecanemab subcutaneous bioavailability study, and subcutaneous dosing is currently being evaluated in the Clarity AD (Study 301) open-label extension (OLE) study.

A maintenance dosing regimen has been evaluated as part of the Phase 2b study. Since July 2020 Eisai's Phase 3 clinical study (AHEAD 3-45) for individuals with preclinical AD, meaning they are clinically normal and have intermediate or elevated levels of amyloid in their brains, is ongoing. AHEAD 3-45 is conducted as a public-private partnership between the Alzheimer's Clinical Trial Consortium that provides the infrastructure for academic clinical trials in AD and related dementias in the U.S, funded by the National Institute on Aging, part of the National Institutes of Health and Eisai.