FDA and EMA Review Apitegromab Applications for Spinal Muscular Atrophy

CAMBRIDGE, MA, USA—Scholar Rock, a biopharmaceutical company focused on creating treatments for serious diseases, has announced that the U.S. Food and Drug Administration (FDA) has accepted their Biologics License Application for apitegromab. This investigational treatment targets muscles to improve motor function in individuals with spinal muscular atrophy (SMA) who are currently receiving SMN-targeted therapies. The FDA has designated a priority review status for this application, setting a target action date under the Prescription Drug User Fee Act (PDUFA) for September 22, 2025. This priority review indicates that apitegromab has the potential to offer significant advancements in the treatment of SMA, a serious condition affecting motor functions.

In parallel with the U.S. progress, Scholar Rock has also submitted a Marketing Authorisation Application to the European Medicines Agency (EMA) for apitegromab, which has been validated, allowing the formal review process by EMA to commence. Scholar Rock CEO Jay Backstrom expressed satisfaction with the FDA’s priority review designation, highlighting the drug’s potential to be a transformative therapy for SMA patients who continue to experience motor function decline despite ongoing SMN-targeted treatments. The company is gearing up for a global commercial launch, starting in the U.S. and followed by Europe.

Apitegromab’s regulatory submissions are supported by promising efficacy and safety data from the Phase 3 SAPPHIRE trial. This pivotal trial demonstrated statistically significant and clinically meaningful improvements in motor function among SMA patients treated with apitegromab alongside chronic SMN-targeted therapies compared to those receiving a placebo. The results, including analyses of primary and secondary endpoints, were recently presented at the 2025 Muscular Dystrophy Association Clinical & Scientific Conference.

Scholar Rock plans to initiate a U.S. commercial launch following potential approval in 2025, with an anticipated European launch in 2026. Apitegromab is a fully human monoclonal antibody that inhibits myostatin activation by binding selectively to its pro- and latent forms in skeletal muscle. This muscle-targeted approach is the first of its kind to show clinical success in a pivotal Phase 3 trial for SMA. Myostatin, a growth factor primarily expressed by skeletal muscle cells, is linked to increased muscle mass and strength when its gene is absent, and Scholar Rock’s selective targeting of this factor could result in improved motor function for SMA patients.

Apitegromab has received various designations from the FDA, including Fast Track, Orphan Drug, and Rare Pediatric Disease, as well as Priority Medicines (PRIME) and Orphan Medicinal Product designations from the EMA. However, it has not yet been approved for use by these or any other regulatory agencies.

The Phase 3 SAPPHIRE trial was a randomized, double-blind, placebo-controlled study assessing the safety and efficacy of apitegromab in nonambulatory patients with Types 2 and 3 SMA who were also receiving standard care treatments such as nusinersen or risdiplam. The trial included 156 patients aged 2-12 years, who were randomized to receive different doses of apitegromab or a placebo over 12 months. An exploratory group of 32 patients aged 13-21 was also evaluated, receiving either apitegromab or placebo.

The SAPPHIRE trial met its primary endpoint for the main efficacy population, showing a statistically significant improvement in motor function as measured by the Hammersmith Functional Motor Scale-Expanded. This outcome underscores the potential of apitegromab as a promising treatment for SMA, paving the way for its anticipated approval and launch.

Scholar Rock continues to drive innovation in the biopharmaceutical field, focusing on therapies that address high unmet medical needs through targeted growth factor modulation. The company’s dedication to advancing the standard of care for neuromuscular diseases and other serious conditions remains at the forefront of its mission.