FDA Approves Isembyld (apitegromab-mstn), the First and Only Muscle-Targeted Therapy for Spinal Muscular Atrophy, Marking a New Milestone in SMA Treatment

New York, Sept. 11, 2026 (GLOBE NEWSWIRE) — The Muscular Dystrophy Association (MDA) marks another milestone for the neuromuscular community with the U.S. Food and Drug Administration (FDA) approval of Isembyld (apitegromab-mstn), a monthly infusion treatment for people living with spinal muscular atrophy (SMA) who are currently receiving a survival motor neuron 2 (SMN2)-targeted treatment. Isembyld (apitegromab-mstn) is the first and only muscle-targeted therapy for SMA, offering new hope for children and adults living with this neuromuscular disease. SMA is a leading genetic cause of death in infants and often requires lifelong support to maintain mobility, breathing, and independence. Today, with more treatments available, people are living longer, more independent lives. Read Scholar Rock’s announcement here.

This milestone builds on more than 75 years of MDA’s legacy of progress, during which the Association has funded research that has led to nearly every approved therapy for neuromuscular diseases, including Isembyld (apitegromab-mstn).

“This is what progress looks like,” said Angela Lek, PhD, Chief Research Officer, MDA. “For decades, Muscular Dystrophy Association has strategically invested in pioneering science and built a research ecosystem that enables scientific discoveries to be translated into disease modifying drugs for patients. We’re thrilled to see regulatory agencies recognize its potential to help people with SMA maintain and improve motor function, independence, and quality of life. Our community has fought hard for these moments, and today we celebrate the momentum of progress.”

This FDA approval reflects the recognition that Isembyld (apitegromab-mstn), represents a significant improvement in treatment. Isembyld (apitegromab-mstn), was designed to improve muscle function in people living with SMA who are already on SMN-targeted therapies, addressing the continued unmet need of motor decline. For families, this milestone is personal.

“Living with SMA hasn’t always been easy for our family, but treatments like Isembyld (apitegromab-mstn) give us hope for a future where Dash can live longer, stronger, and more independently,” said Amanda Stanton, whose son Dash, an MDA Ambassador, lives with SMA. “We want him to keep doing the things he loves without worrying that his muscles will stop keeping up with him. This news feels like a big step forward, not just for Dash, but for everyone living with SMA.”

“The Muscular Dystrophy Association’s support was absolutely pivotal in the early days of my research. Their investment enabled me to explore the biology of myostatin and demonstrate that blocking it could profoundly increase muscle growth. That work elucidating key regulatory components and mechanisms became the conceptual foundation for all anti-myostatin therapies developed since. To see this science now potentially helping people living with SMA through a therapy like Isembyld (apitegromab-mstn) is incredibly meaningful. It’s a powerful example of how sustained research investment can translate into real impact for families,” said Se-Jin Lee, MD, PhD, University of Connecticut School of Medicine and The Jackson Laboratory.

Watch the video story here.

Isembyld (apitegromab-mstn) was approved based on positive results from the pivotal Phase 3 SAPPHIRE study, supported by earlier studies including TOPAZ and ONYX, which demonstrated clinically meaningful improvements in motor function for people living with SMA. Additional analyses from the SAPPHIRE study, including outcomes in nonambulatory  people with Type 2 or Type 3 SMA, were presented at the 2026 MDA Clinical & Scientific Conference, in a poster titled, “Post hoc analyses from the Phase 3 SAPPHIRE study evaluating apitegromab in patients with nonambulatory type 2 or 3 spinal muscular atrophy.”

“The approval of Isembyld (apitegromab-mstn) marks a significant step forward for people living with SMA,” said Pediatric Neurologist, Randal Richardson, MD, MDA Care Center Director at Gillette Children’s Hospital in Saint Paul, Minnesota. “The era of stopping or slowing SMA progression has evolved to a new one focused on improving function. This is the first muscle-directed therapy that can work alongside the remarkable SMN-enhancing treatments we’ve seen transform care in recent years. This milestone reflects decades of progress driven by partners like the Muscular Dystrophy Association and brings new hope to families in the SMA community.”

Industry Update Webinars
Families and clinicians can learn more about Isembyld (apitegromab-mstn) during one of Scholar Rock’s upcoming Industry Update Webinars:

• Families – October 6, 2026 – Scholar Rock community webinar
• Clinicians – October 7, 2026 – Scholar Rock clinician webinar

MDA Research, Care, and Advocacy
Today’s approval underscores MDA’s enduring role in advancing therapies for neuromuscular diseases. Since its inception, MDA has invested more than $1.2 billion in research, including over $50 million in spinal muscular atrophy (SMA), helping pave the way for more than 30 FDA-approved treatments in the last decade. Beyond research, MDA drives progress through its advocacy, nationwide MDA Care Center Network at over 150 top medical institutions, as well as the MDA Resource Center and Gene Therapy Support Network, which provide guidance and support for families living with SMA and more than 300 related neuromuscular conditions. For the SMA community, this milestone represents not only scientific progress, but also a testament to resilience, hope, and renewed possibility.

MDA Support
For more information on SMA, and ongoing support for families and medical professionals, contact the MDA Resource Center by phone 1-833-ASK-MDA1 (1-833-275-6321) or email [email protected]. 

Media inquiries contact [email protected].  

About Muscular Dystrophy Association
Muscular Dystrophy Association (MDA) has been at the center of progress for people living with muscular dystrophy, ALS, and over 300 other neuromuscular conditions for over 75 years. We unite researchers, clinicians, advocates, and families to speed the pace of discovery, improve access to expert care, and ensure inclusion in every aspect of life. Our mission is simple: give the people we serve the tools and opportunities to live longer, more independent lives. To learn more visit mda.org. Follow MDA on social media on Instagram, Facebook, X, TikTok, LinkedIn, and YouTube.

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• FDA Approves Isembyld (apitegromab-mstn), the First and Only Muscle-Targeted Therapy for Spinal Muscular Atrophy, Marking a New Milestone in SMA Treatment

CONTACT: Mary Fiance, National Vice President, Strategic Communications
Muscular Dystrophy Association
[email protected]