Chugai Launches Japan's First Gene Therapy for Duchenne Muscular Dystrophy
Key Insights
Chugai Pharmaceutical launched ELEVIDYS as Japan's first regenerative medical product for Duchenne muscular dystrophy (search), marking a significant milestone in rare disease treatment.
The gene therapy is approved for ambulatory DMD (search) patients aged 3-8 years who test negative for anti-AAVrh74 (search) antibodies and meet specific genetic criteria.
ELEVIDYS received conditional approval based on the EMBARK Phase III study, though the primary endpoint did not reach statistical significance at 52 weeks.
Chugai Pharmaceutical Co., Ltd. announced the commercial launch of ELEVIDYS® Intravenous Infusion (delandistrogene moxeparvovec) in Japan on February 20, 2026, marking the country's first regenerative medical product approved for treating Duchenne muscular dystrophy (search) (DMD (search)). The gene therapy received conditional and time-limited approval on May 13, 2025, and was added to Japan's national health insurance reimbursement price list.
Targeted Patient Population and Eligibility
ELEVIDYS is indicated for a specific subset of DMD (search) patients who meet stringent criteria. Eligible patients must be ambulatory, aged 3 years to less than 8 years, test negative for anti-AAVrh74 (search) antibodies, and cannot have deletions in exon 8 and/or exon 9 of the DMD gene (search). The therapy is administered as a single intravenous infusion, with dosing based on patient weight: 1.33×10¹⁴ vector genomes per kilogram for patients weighing 10-70 kg, or a fixed dose of 9.31×10¹⁵ vector genomes for those weighing 70 kg or more.
"DMD (search) is a progressive disease that begins in early childhood and significantly impacts daily life due to gradual muscle weakness," said Dr. Osamu Okuda, Chugai's President and CEO. "We are very pleased to be able to deliver ELEVIDYS to patients diagnosed with DMD and their families who have been eagerly awaiting new treatment options."
Clinical Evidence and Regulatory Approval
The approval is based on results from the global Phase III EMBARK study, which evaluated ELEVIDYS efficacy and safety for up to two years in 125 ambulatory boys with DMD (search) aged 4-7 years. The multinational, randomized, double-blind, two-part crossover, placebo-controlled trial used a 1.33×10¹⁴ vg/kg dose of delandistrogene moxeparvovec.
While the primary endpoint measuring motor function through the North Star Ambulatory Assessment (NSAA) did not achieve statistical significance at 52 weeks compared to placebo, clinically meaningful improvements were observed in key secondary endpoints. These included time to rise from the floor, 10-meter walk time, stride velocity 95th centile, and time to ascend 4 steps.
Safety Concerns and Enhanced Monitoring
The launch comes with heightened safety measures following reports of two fatal cases of acute liver failure (search) in non-ambulatory DMD (search) patients treated with ELEVIDYS overseas. In response, Chugai has implemented comprehensive safety protocols, including revised electronic package inserts and educational materials for healthcare professionals and patients.
The company established a framework for promoting appropriate use through industry-government-academia collaboration and developed specialized materials including an Appropriate Use Guide and Patient Handbook. Additionally, a specialist consultation framework has been created through the Japanese Society of Child Neurology, featuring internet-based consultation via BRIDGE-NMD, a multidisciplinary expert panel comprising specialists in pediatric neurology, hepatology, hepatobiliary surgery, cardiology, immunology, nephrology, and hematology.
Companion Diagnostic and Market Access
For patient eligibility determination, Roche Diagnostics (search) K.K. launched the Elecsys anti-AAVrh74 (search) assay in Japan on February 1, 2026, as a companion diagnostic to detect anti-AAVrh74 antibody negativity prior to ELEVIDYS administration. The therapy carries a substantial price of JPY 304,972,042 per patient, determined through official rules following discussions at the Central Social Insurance Medical Council.
Disease Background and Unmet Need
DMD (search) affects approximately one in 5,000 boys worldwide and represents a rare, genetic muscle-wasting disease that progresses rapidly from early childhood. The condition is caused by mutations in the DMD gene (search), which affects production of dystrophin (search), a critical muscle protein component that strengthens muscle fibers and protects them from injury during contraction. Without functional dystrophin, muscle cells become more sensitive to injury, and muscle tissue is progressively replaced with scar tissue and fat.
All patients with DMD (search) eventually lose walking ability, upper limb function, lung and cardiac function, leading to fatal outcomes. The diagnosis requires full-time caregiving, typically provided by parents, with the majority finding it difficult to carry out usual work or household activities while suffering from depression, physical pain, and discomfort.
Global Regulatory Status
ELEVIDYS was first approved in the United States in June 2023 as the first gene therapy for DMD (search), though the indication for non-ambulatory patients was subsequently removed following the fatal liver failure cases. In Europe, the Committee for Medicinal Products for Human Use of the European Medicines Agency recommended against granting conditional marketing approval, with the European Commission endorsing this recommendation in September 2025. The therapy is currently approved for ambulatory DMD patients in nine countries worldwide.
The conditional approval in Japan includes a three-year time limit and requires post-marketing clinical studies and all-case surveillance to confirm long-term efficacy and safety. ELEVIDYS was originated by Sarepta Therapeutics, co-developed with Roche, and in-licensed to Chugai, which holds exclusive marketing rights in Japan.