Eisai Co., Ltd. and Biogen Inc. announced that the Therapeutic Goods Administration (TGA) of Australia has approved LEQEMBI® (lecanemab), a humanized anti-soluble aggregated amyloid-beta (Aβ) monoclonal antibody, for the treatment of adults with mild cognitive impairment (MCI) or mild dementia due to Alzheimer’s disease (AD) – collectively referred to as early AD – who are either ApoEε4 non-carriers or heterozygous carriers.

This approval follows a February 2025 decision by the TGA not to approve lecanemab for early AD. Eisai subsequently requested a review by the Administrative Review Tribunal in March 2025. As a result of constructive discussions during the process, an agreement was reached with the TGA that led to today’s approval of LEQEMBI.

Addressing an Urgent and Growing Unmet Need in Australia

In 2024, it was estimated that approximately 425,000 people were living with dementia in Australia, a number projected to rise to nearly 1.1 million by 2065. Alzheimer’s disease, the most common cause of dementia, typically accounts for 60–70% of all cases. AD is a progressive, debilitating disease marked by the accumulation of amyloid beta (Aβ) and tau proteins, which lead to ongoing neurotoxic processes and cognitive decline.

LEQEMBI is the first and only approved treatment that acts in two distinct ways against AD:

• Targeting toxic protofibrils – believed to be the most damaging form of Aβ, associated with neuronal injury and cognitive decline.

• Reducing amyloid plaque – which can impact tau pathology downstream.

Regulatory and Commercial Leadership

Eisai is the lead for global development and regulatory submissions of lecanemab. Eisai and Biogen will continue to co-commercialize and co-promote LEQEMBI worldwide, with Eisai retaining final decision-making authority.

Safety Information

Apolipoprotein E (ApoE) status is an important factor in Alzheimer’s disease treatment. Individuals with two copies of ApoEε4 (homozygous) are at higher risk for amyloid-related imaging abnormalities (ARIA), a recognized side effect of lecanemab involving brain swelling and potential bleeding. The TGA approval reflects this clinical consideration by limiting treatment to non-carriers and heterozygous carriers of ApoEε4.

Executive Commentary

“Today’s approval of LEQEMBI in Australia represents a meaningful step forward for patients and families facing early Alzheimer’s disease,” said Haruo Naito, CEO at Eisai. “By targeting protofibrils, which are thought to be the most toxic form of amyloid beta, LEQEMBI addresses the root biology of Alzheimer’s and helps advance the fight against this devastating disease.”

“Alzheimer’s disease is one of the most urgent healthcare challenges of our time,” said Christopher A. Viehbacher, CEO at Biogen. “We are proud to work with Eisai to bring LEQEMBI to patients in Australia, where the need for innovative therapies is growing rapidly as the population ages.”