FDA Approves Isembyld as First Muscle-Targeted Treatment for Spinal Muscular Atrophy
- Scholar Rock has secured Food and Drug Administration approval for Isembyld, the first muscle-targeted therapy designed to treat spinal muscular atrophy in adults and children aged two and...
- The FDA approval is based on findings from the Phase 3 randomized, placebo-controlled SAPPHIRE study, according to disclosures from Scholar Rock.
- Hallal, chairman and chief executive officer of Scholar Rock, described the authorization as a defining moment for the patient community.
Scholar Rock has secured Food and Drug Administration approval for Isembyld, the first muscle-targeted therapy designed to treat spinal muscular atrophy in adults and children aged two and older, according to company announcements on September 11, 2026. The drug, scientifically known as apitegromab-mstn, is approved for patients who are already receiving survival motor neuron 2 targeted treatments, offering a new approach to combat progressive muscle wasting in a rare and severe neuromuscular disease.
Clinical Trial Results and Efficacy Data
The FDA approval is based on findings from the Phase 3 randomized, placebo-controlled SAPPHIRE study, according to disclosures from Scholar Rock. The trial met its primary endpoint by showing a statistically significant motor function improvement in patients receiving the therapy. Patients treated with a recommended dose of 10 mg/kg of Isembyld demonstrated a 2.2-point improvement in motor function after one year, measured by the Hammersmith Functional Motor Scale-Expanded compared to a placebo group, with a nominal p-value of 0.0121, according to company data. Furthermore, 34.2 percent of patients receiving the drug achieved an increase of three points or more on the scale, compared to 13.5 percent of patients in the placebo group, yielding an odds ratio of 3.8 and a nominal p-value of 0.0125.
Industry Significance and Patient Access
David L. Hallal, chairman and chief executive officer of Scholar Rock, described the authorization as a defining moment for the patient community.
Today’s FDA approval of ISEMBYLD marks a defining moment for the SMA community as we now launch the world’s first-ever muscle targeted treatment for children and adults living with SMA in the U.S.
David L. Hallal, Scholar RockScholar Rock Hallal added that after decades of failed industry-wide efforts to unlock the potential of myostatin inhibition, the company has delivered a therapeutic breakthrough.
The company stated that its commercial launch is underway, with product shipments expected in the days following the announcement, and a dedicated support team established to assist patients and caregivers. Management plans to host an investor call on September 14, 2026, at 8:00 a.m. Eastern Time.