Scholar Rock (NASDAQ: SRRK), a late-stage biopharmaceutical company dedicated to developing innovative treatments for spinal muscular atrophy (SMA), cardiometabolic disorders, and other severe conditions driven by protein growth factors, has officially submitted a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) for apitegromab. This muscle-targeted therapy aims to provide clinically meaningful improvements in motor function for SMA patients already receiving SMN-targeted treatments. The company also plans to submit a Marketing Authorisation Application to the European Medicines Agency (EMA) in the first quarter of 2025.
Dr. Jing Marantz, Chief Medical Officer at Scholar Rock, expressed confidence in the application, citing the success of the SAPPHIRE Phase 3 trial. The trial’s primary endpoint demonstrated a statistically significant 1.8-point improvement in motor function for patients treated with apitegromab compared to placebo, as measured by the Hammersmith Functional Motor Scale-Expanded at week 52. Marantz emphasized the strength of the Phase 3 data and the company’s commitment to working closely with the FDA to secure approval on behalf of SMA patients and their families.
The FDA’s Division of Neurology Products will review the BLA, which is backed by data from both the Phase 3 SAPPHIRE trial and the Phase 2 TOPAZ trial. Scholar Rock has also requested Priority Review, which, if granted, would reduce the FDA’s review time to six months from the date of acceptance. Apitegromab has already received Fast Track, Orphan Drug, and Rare Pediatric Disease designations from the FDA. Additionally, the EMA has granted it Priority Medicines (PRIME) and Orphan Medicinal Product designations.
Looking ahead, Scholar Rock intends to expand its research on apitegromab through the Phase 2 OPAL trial, scheduled to launch in mid-2025. This trial will assess the therapy in SMA patients under two years old who have received or are currently undergoing treatment with any approved SMN therapy, including nusinersen, risdiplam, or onasemnogene abeparvovec.
About Apitegromab
Apitegromab is an investigational, fully human monoclonal antibody designed to inhibit myostatin activation. By selectively binding to the pro- and latent forms of myostatin in skeletal muscle, apitegromab is the first muscle-targeted treatment candidate to demonstrate statistically significant and clinically meaningful motor function improvements in a pivotal Phase 3 trial for SMA. Myostatin is a member of the transforming growth factor beta (TGFβ) superfamily and is primarily expressed by skeletal muscle cells. Research indicates that genetic deletion of myostatin results in increased muscle mass and strength across multiple animal species, including humans.
Despite the promising results, apitegromab remains an investigational therapy and has not yet been approved for use by the FDA or any other regulatory body. However, its regulatory designations from both the FDA and EMA highlight its potential impact on the SMA treatment landscape.
About the Phase 3 SAPPHIRE Trial
SAPPHIRE was a randomized, double-blind, placebo-controlled Phase 3 trial evaluating the safety and efficacy of apitegromab in nonambulatory patients with Types 2 and 3 SMA. The trial focused on patients receiving standard SMA treatments such as nusinersen or risdiplam.
The primary efficacy population consisted of 156 patients aged 2-12, randomized in a 1:1:1 ratio to receive either 10 mg/kg or 20 mg/kg of apitegromab or a placebo, administered via intravenous infusion every four weeks for 12 months. Additionally, an exploratory cohort of 32 patients aged 13-21 was included, with a 2:1 randomization for 20 mg/kg of apitegromab versus placebo.
The study met its primary endpoint, demonstrating a statistically significant 1.8-point improvement on the Hammersmith Functional Motor Scale-Expanded (HFMSE) for the primary efficacy group receiving apitegromab. These results bolster apitegromab’s potential as a transformative therapy for SMA patients who are already on SMN-targeted treatments.
About Scholar Rock
Scholar Rock is a clinical-stage biopharmaceutical company committed to discovering, developing, and delivering innovative treatments for serious diseases driven by protein growth factors. Named for the resemblance of a scholar rock to protein structures, the company is a recognized leader in the biology of the TGFβ superfamily. Its pioneering research has led to a pipeline of novel therapies that aim to redefine treatment paradigms for neuromuscular diseases, cardiometabolic disorders, cancer, and other conditions where growth factor-targeted interventions hold promise.
Scholar Rock’s proprietary platform enables the design of monoclonal antibodies that modulate protein growth factors with exceptional selectivity. By leveraging advanced scientific insights, the company is committed to addressing historically unmet medical needs through breakthrough therapies.
Investor and Public Engagement
Scholar Rock actively communicates with investors and the public through its website, www.scholarrock.com, and social media channels, including Twitter and LinkedIn. These platforms provide company updates, investor presentations, regulatory filings, press releases, and conference call transcripts. While this information may be deemed material, it is not incorporated by reference in any regulatory filing under the Securities Act of 1933.
Scholar Rock® is a registered trademark of Scholar Rock, Inc.
As the company moves forward with regulatory submissions in both the U.S. and Europe, the potential approval of apitegromab could mark a significant milestone in the treatment of SMA, offering new hope for patients and their families.
