Cambridge, Mass. — Scholar Rock said the U.S. Food and Drug Administration has approved Isembyld, or apitegromab-mstn, for the treatment of spinal muscular atrophy in adults and children age 2 and older who are receiving a survival motor neuron 2-targeted treatment.
Isembyld is a muscle-targeted therapy designed to improve motor function in patients with spinal muscular atrophy, a rare neuromuscular disease that causes progressive muscle wasting and loss of motor function.
The approval was based on results from the Phase 3 SAPPHIRE study, a randomized, double-blind, placebo-controlled trial.
Patients receiving Isembyld at 10 mg/kg in addition to an SMN2-targeted therapy showed a 2.2-point improvement in the Hammersmith Functional Motor Scale-Expanded compared with patients receiving background therapy alone after one year.
In addition, 34.2% of patients receiving Isembyld achieved an increase of at least three points on the HFMSE compared with 13.5% of patients receiving placebo.
“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.,” said David L. Hallal, Chairman and Chief Executive Officer of Scholar Rock.
Scholar Rock said the safety database for apitegromab includes more than 500 patients across clinical studies, with some receiving treatment for more than seven years.
The most common adverse reactions in the SAPPHIRE study included upper respiratory tract infections, vomiting, cough, viral infections, headache, gastroenteritis, pharyngitis and hypersensitivity. Fractures occurred in 9% of patients receiving Isembyld 10 mg/kg compared with 2% receiving placebo.
The FDA approval also earned Scholar Rock a Rare Pediatric Disease Priority Review Voucher, which can be used to obtain priority review for a future marketing application.
Scholar Rock said the U.S. commercial launch of Isembyld is underway, with product expected to become available for shipment in the coming days.
