Biogen Inc. and its partner Eisai Co. filed a new drug application with Japan’s Pharmaceuticals and Medical Devices Agency on November 27, 2025 for a subcutaneous autoinjector formulation of LEQEMBI (lecanemab). The filing follows the U.S. Food and Drug Administration’s August 2025 approval of a subcutaneous maintenance regimen and builds on the 2023 Japanese approval of the intravenous product.
The proposed autoinjector delivers a 500 mg weekly dose that, according to data from the Phase 3 Clarity AD open‑label extension, achieves drug exposure equivalent to the current 10 mg/kg bi‑weekly intravenous regimen while maintaining similar clinical benefits. The data set includes safety, pharmacokinetics, and efficacy outcomes that support the equivalence claim and provide a robust basis for the Japanese submission.
By enabling at‑home administration, the subcutaneous formulation could reduce the need for infusion‑center visits, lower logistical costs, and broaden access for patients and caregivers in Japan’s aging population. The move also positions LEQEMBI more competitively against emerging Alzheimer’s therapies that emphasize patient convenience and home‑based delivery, potentially accelerating market penetration and adoption rates.
Biogen’s broader commercial strategy has been shaped by a mix of legacy product declines and new‑product growth. In Q4 2024, the company reported total revenue of $2.5 billion, a 3% year‑over‑year increase, while full‑year 2024 revenue slipped 2% to $9.7 billion. LEQEMBI’s global in‑market sales reached approximately $87 million in Q4 2024, underscoring the drug’s importance to Biogen’s portfolio. The partnership with Eisai, which holds final decision‑making authority, reflects a shared commitment to expanding LEQEMBI’s global reach and optimizing its delivery platform.
The filing aligns with the broader regulatory trajectory for LEQEMBI, which has secured approvals in the U.S., Europe, and Japan for both intravenous and subcutaneous routes. The Japanese submission is a strategic step to capture a market that values home‑based care, and it complements the U.S. subcutaneous approval that has already broadened patient access. The move is expected to strengthen the competitive position of both companies in the Alzheimer’s treatment landscape and could set a precedent for future subcutaneous formulations of biologics in Japan.
The subcutaneous option is anticipated to improve adherence and reduce infusion‑center demand, potentially translating into higher market share for LEQEMBI in Japan. As the aging population grows, the demand for convenient, home‑based Alzheimer’s therapies is likely to increase, positioning the new formulation to capture a significant share of the expanding market.
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