Kyowa Kirin and Orchard Therapeutics’ Gene Therapy for MLD Earns Key Designations in Japan and Saudi Arabia

TOKYO, JAPAN & BOSTON, MA — October 28, 2025 — Kyowa Kirin Co., Ltd. and Orchard Therapeutics today announced that Japan’s Ministry of Health, Labor and Welfare (MHLW) has granted Orphan Regenerative Medicine Product Designation to OTL-200 (also known as atidarsagene autotemcel).

OTL-200 is an investigational ex vivo autologous hematopoietic stem cell (HSC) gene therapy for the treatment of early-onset metachromatic leukodystrophy (MLD)—an ultra-rare, rapidly progressive, and fatal neurometabolic disease affecting approximately one in 100,000 live births. The designation covers pre-symptomatic late infantile (PSLI), pre-symptomatic early juvenile (PSEJ), and early-symptomatic early juvenile (ESEJ) forms of the disease.

Global Momentum for Single-Dose Therapy

MLD is caused by an error in the gene encoding the ARSA enzyme, leading to severe neurological damage and developmental regression. Children with the most severe form rapidly lose the ability to walk and talk, often passing away within five years of symptom onset. Currently, no approved therapies exist for MLD in Japan beyond supportive care.

• OTL-200 Mechanism: The therapy aims to correct the underlying genetic cause by using a lentiviral vector to insert functional copies of the human ARSA gene into the patient’s own HSCs outside the body. These genetically repaired cells are then infused back, migrate to the central nervous system, and express the necessary functional enzyme with a single administration.
• International Status: OTL-200 is already approved and marketed as Lenmeldy™ in the United States and Libmeldy® in Europe, establishing it as the only therapy intended to correct the underlying cause of MLD for eligible patients.

Expanding Access in the Middle East

In addition to the Japanese designation, OTL-200 has also received Orphan Drug Designation and Priority Review from the Saudi Food and Drug Authority (SFDA). These designations are intended to expedite the review process for new therapies targeting rare diseases in the Kingdom of Saudi Arabia.

Orchard Therapeutics is concurrently working to qualify a treatment center in Saudi Arabia to administer the therapy to eligible children from the country and surrounding regions through pre-approval access pathways.

Takeyoshi Yamashita, Ph.D., Executive Vice President and Chief Medical Officer of Kyowa Kirin, stated, “This designation underscores the importance of OTL-200 as an innovative treatment for young patients suffering from MLD… We are committed to promptly advancing the development of OTL-200 to deliver life-changing value to patients and their families in Japan, working to make this therapy available to patients in other regions worldwide.”

Kyowa Kirin is now preparing to initiate a clinical trial for OTL-200 in children with early-onset MLD in Japan.