SOLVE FSHD Accelerates Development of SFH-4090, a Novel DUX4 Inhibitor for FSHD

• SOLVE FSHD announces new nonclinical data supporting SFH-4090 development for FSHD, a progressive muscle-wasting disease with no approved disease-modifying therapies
• The data, presented at the World Muscle Society Annual Congress 2026, build on SFH-4090’s novel chemistry for ASO therapies, with improved tissue penetration following subcutaneous delivery
• Findings show SFH-4090 reaches and remains in skeletal muscle, addressing a long-standing delivery challenge in ASO development for neuromuscular diseases

VANCOUVER, British Columbia--(BUSINESS WIRE)--SOLVE FSHD today announced new nonclinical data supporting SFH-4090 for the treatment of facioscapulohumeral muscular dystrophy (FSHD). The data were presented at the 31st Annual Congress of the World Muscle Society (WMS).

SFH-4090, also known as MT-4090, discovered by Tanabe Pharma Corporation (Head Office: Osaka, Japan; Representative Director, CEO: Akihisa Harada), is a chemically novel antisense oligonucleotide (ASO) designed to reduce the expression of DUX4, the pathogenic driver of FSHD. Through their collaboration, SOLVE FSHD and Tanabe Pharma have advanced SFH-4090 toward clinical trial readiness as a potential disease-modifying treatment for FSHD. The investigational therapy has been granted Orphan Drug Designation by the FDA.

FSHD is a rare, genetic and progressive muscle-wasting disease affecting an estimated 870,000 people worldwide, with no currently approved disease-modifying therapies.

New Data Support Continued Development of SFH-4090

The nonclinical data indicate robust efficacy with a large safety margin of SFH-4090, with skeletal muscle exposure sustained above the efficacious levels required, and predictable plasma and tissue pharmacokinetics.

In non-human primates, concentrations of SFH-4090 in skeletal muscle were approximately 18 times higher than in plasma following weekly subcutaneous administration for 13 weeks. Muscle concentrations were sustained over time, with an apparent terminal half-life of approximately 16 days in both rats and non-human primates. Together with its subcutaneous route of administration, these pharmacokinetic properties support the potential for a patient-friendly dosing regimen as SFH-4090 advances toward clinical development.

Researchers also compared drug levels observed in rat and non-human primate studies with levels associated with efficacy in an FSHD mouse model. In mice, SFH-4090 was associated with reduced DUX4-related gene activity and improved motor function. Skeletal muscle levels achieved in rat and non-human primate studies met or exceeded those linked to efficacy in mice, supporting continued development.

Naoya Masutomi, Executive Officer, Head of Research Division, Tanabe Pharma Corporation: “Efficient delivery of ASO therapies to skeletal muscle has historically been a significant challenge in developing treatments for neuromuscular diseases. By showing sustained skeletal muscle exposure at levels considered relevant for FSHD, these findings provide important support for the further development of SFH-4090 as a potential muscle-targeted therapy. The subcutaneous route of administration may also be relevant as the program advances, including future considerations around treatment delivery for patients.”

Eva Chin, Executive Director, SOLVE FSHD: “As a mission-focused venture philanthropy organization, SOLVE FSHD is committed to accelerating the development of transformative therapies for people living with FSHD. We partnered with Tanabe Pharma because of the potential of SFH-4090 to target a central driver of the disease, its large safety margin and the long-term vision of at-home treatment for FSHD patients. These new findings further support the continued development of SFH-4090 as a potential disease-modifying treatment and reinforce the role of strategic collaboration in advancing therapies for FSHD.”

About FSHD

Facioscapulohumeral muscular dystrophy, or FSHD, is a rare, genetic and progressive muscle-wasting disease with no approved disease-modifying treatments. It is associated with progressive muscle weakness that can lead to pain, fatigue, disability and loss of independence.

Symptoms may begin in childhood or adulthood, and the impact and progression can vary significantly from person to person. FSHD often first affects muscles in the face, shoulders and upper arms, but can involve muscles throughout the body. Around 20% of people living with FSHD require a wheelchair by age 50.

DUX4 is widely recognized as a central therapeutic target in FSHD, and clinical development efforts targeting the underlying biology of the disease have accelerated in recent years. However, there remains a high unmet need for therapies that can modify disease progression and improve outcomes for people living with FSHD.

About SOLVE FSHD

SOLVE FSHD is a venture philanthropic organization dedicated to accelerating treatments for FSHD. SOLVE FSHD provides foundational and strategic funding to de-risk and catalyze the most promising pathways to effective therapies. More information is available at www.solvefshd.com.

About Tanabe Pharma

Tanabe Pharma Corporation is a Japan-focused, innovation-driven pharmaceutical company guided by its mission, "Creating hope for all facing illness." Founded in 1678, the company is one of Japan's oldest pharmaceutical companies and is committed to addressing unmet medical needs through R&D, business development, and strategic partnerships with the aim of improving the lives of patients. For more information, visit https://www.tanabe-pharma.com/en/.