• 02 Dec 2025
• Admin
• News Article

Eisai and Biogen Seek Approval for At-Home Leqembi Autoinjector in Japan

Eisai and Biogen have taken a major step toward expanding treatment access for Alzheimer’s disease. Eisai has filed a new drug application in Japan for a subcutaneous autoinjector (SC-AI) version of Leqembi (lecanemab), aiming to offer patients a convenient at-home dosing option.

A New Administration Route for Early Alzheimer’s Treatment

The filing follows multiple sub-studies within the Clarity AD Phase 3 open-label extension. These studies included individuals with Mild Cognitive Impairment due to Alzheimer’s or mild AD dementia.

Key findings:

• Once-weekly SC-AI 500 mg dosing achieved drug exposure equivalent to the IV dose given every two weeks.
• Clinical and biomarker benefits were similar to IV administration.
• Safety was comparable, with <2% systemic injection or infusion reactions.

The data show that weekly autoinjector dosing can match the impact of clinic-based IV infusions.

What the Autoinjector Could Change?

If approved, patients could self-administer Leqembi at home, using two 250 mg injections once per week. Each injection takes about 15 seconds.

This shift could:

• Reduce dependence on hospital visits
• Lower healthcare resource use tied to IV preparation and monitoring
• Streamline the Alzheimer’s treatment pathway
• Improve convenience for patients and caregivers

For many families managing early AD, this is more than a formulation change—it’s a lifestyle improvement.

How Leqembi Works?

Alzheimer’s disease is driven by toxic amyloid-beta protofibrils that appear before amyloid plaque buildup. Leqembi targets both:

• Protofibrils (the upstream driver)
• Amyloid plaques (the downstream accumulation)

By reducing these abnormal proteins, Leqembi helps slow disease progression in early AD.

Global Status of Leqembi

Leqembi is currently:

• Approved in 51 countries, including Japan, the U.S., Europe, China and others
• Under review in 9 countries
• Approved across different dosing formats:
  - IV every two weeks (initial treatment)
  - IV every four weeks (maintenance)
  - SC maintenance dosing (U.S., China, U.K.)

The subcutaneous maintenance version, Leqembi IQLIK, received FDA approval in August 2025.

A rolling sBLA for SC initiation therapy was completed in November 2025.

Ongoing Long-Term Studies

Two major trials continue to shape the future of Alzheimer’s therapy:

• AHEAD 3-45: For individuals with preclinical AD who are clinically normal but show elevated amyloid.
  A public-private collaboration involving NIA, ACTC, Eisai and Biogen.
• Tau NexGen (DIAN-TU): For dominantly inherited AD, using lecanemab as the backbone anti-amyloid therapy.

These studies aim to test whether early intervention can delay or prevent symptomatic Alzheimer’s.

The Collaboration Behind Leqembi

Eisai and Biogen have been partners in Alzheimer’s drug development since 2014.

• Eisai leads global development and regulatory submissions.
• Both companies co-promote and co-commercialize Leqembi.
• BioArctic originally discovered the antibody platform behind lecanemab.

The partnership spans nearly two decades and reflects a long-term effort to change the trajectory of Alzheimer’s disease worldwide.

About the Companies

Eisai

A global pharmaceutical company focused on its human health care (hhc) mission: improving patient well-being and reducing health-related anxieties through purposeful innovation.

Biogen

A biotechnology pioneer founded in 1978. Known for advancing therapies for neurological diseases and delivering meaningful value to patients and communities.