FDA 批准 Scholar Rock 的 SMA 肌肉靶向药 ISEMBYLD（apitegromab-mstn），公司由临床阶段转为商业化阶段，股价周五盘后一度冲 +26% 后回落至 +12%

Scholar Rock Holding (SRRK) surged 12% in extended trading Friday after the Food and Drug Administration approved isembyld, the company’s treatment for spinal muscular atrophy.
Isembyld, also known as apitegromab-mstn, was approved for adults and children ages 2 and older who are already receiving a treatment targeting survival motor neuron 2, or SMN2. Scholar Rock (SRRK) described isembyld as the first and only approved SMA treatment that directly targets muscle.
The Cambridge, Massachusetts-based biotechnology company said its U.S. commercial launch is underway, with the drug expected to become available for shipment in the coming days. Its Scholar Rock Supports program will help patients and caregivers navigate insurance coverage, financial assistance and infusion arrangements.
For investors, the approval transforms Scholar Rock (SRRK) from a clinical-stage biotechnology company into a commercial drugmaker and removes a major regulatory risk surrounding its lead product. Attention now shifts to isembyld’s pricing, insurance coverage and adoption among patients already taking established SMN2 therapies.
The broad label, covering adults as well as children ages 2 and older, may expand the addressable market. Scholar Rock (SRRK) also received a rare pediatric disease priority review voucher, an asset that could be used to accelerate review of another drug application or potentially be sold to another company.
FDA approval was based on the Phase 3 SAPPHIRE study, which evaluated isembyld in combination with existing SMN2-targeted therapy.
Patients receiving the recommended 10-milligram-per-kilogram dose showed a 2.2-point improvement over placebo after one year on the Hammersmith Functional Motor Scale-Expanded, a standard measure of physical abilities in people with SMA. The analysis covered 103 patients ages 2 through 12.
The company also reported that 34.2% of patients receiving isembyld achieved an improvement of at least three points on the scale, compared with 13.5% of patients receiving placebo. That represented an odds ratio of 3.8.
Scholar Rock (SRRK) said 98% of SAPPHIRE participants chose to enter the ONYX long-term extension study. Its broader safety database includes more than 500 people, some of whom have received apitegromab for more than seven years.
The most common adverse reactions in SAPPHIRE included upper respiratory infections, vomiting, cough, headache, gastroenteritis, pharyngitis and hypersensitivity. Fractures occurred in 9% of patients receiving the approved dose, compared with 2% of those receiving placebo.
SMA causes the progressive loss of motor neurons and muscle function. Existing therapies address the genetic or neurological basis of the disease, while ISEMBYLD is intended to improve muscle function alongside those treatments.
Scholar Rock (SRRK) will discuss the approval and commercial rollout during an investor call Monday at 8 a.m. Eastern time.