Business Description

1. Nature of the Business and Basis of Presentation Organization Scholar Rock Holding Corporation and its subsidiaries (collectively, the “Company”) is a global biopharmaceutical company dedicated to dramatically improving the lives of children and adults with spinal muscular atrophy (“SMA”) and additional rare, severe and debilitating neuromuscular diseases. As a leader in the biology of the transforming growth factor beta (“TGFβ”) superfamily, the Company’s novel understanding of the molecular mechanisms of growth factor activation enabled the development of a proprietary platform for the discovery and development of monoclonal antibodies that locally and selectively target the precursor, or latent, forms of growth factors. Based on the Company’s innovative, proprietary, and scalable technology platform, the Company is building a world-leading anti-myostatin pipeline. The Company’s lead pipeline product candidates include apitegromab, a subcutaneous formulation of apitegromab, and SRK-439. Apitegromab is a novel, investigational, fully human monoclonal antibody that inhibits myostatin activation by selectively binding the pro- and latent forms of myostatin in skeletal muscle. Myostatin is a catabolic agent that functions as a negative regulator of muscle mass, therefore inhibition of myostatin results in increased muscle mass and strength. Apitegromab is in development for the treatment of people with SMA and for the treatment of people with facioscapulohumeral muscular dystrophy (“FSHD”). Positive data from the successful Phase 3 SAPPHIRE study evaluating apitegromab in children and adults with SMA was reported in October 2024. The Company submitted a U.S. Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) in January 2025 and the BLA was granted priority review designation. In September 2025, the Company received a Complete Response Letter (“CRL”) from the FDA related to observations identified during an FDA inspection of a third-party fill-finish facility. The facility was issued a Form 483 by the FDA in July 2025 and the inspection classification of this facility is official action indicated (“OAI”). The observations were related to the facility and were not specific to apitegromab. The CRL did not cite any other approvability concerns, including apitegromab’s efficacy and safety data or the third-party drug substance manufacturer. In November 2025, the Company completed an in-person Type A meeting with the FDA that included participation of representatives from the third-party fill-finish facility. Also in November 2025, the third-party fill-finish facility received a Warning Letter from the FDA and continues to work with the FDA to resolve the outstanding issues cited in the warning letter. The Company plans to resubmit the apitegromab BLA at such time after the facility resolves the cGMP deficiencies identified in the CRL. In March 2025, the Company submitted to the European Medicines Agency (“EMA”) and received validation of its marketing authorisation application (“MAA”) for apitegromab for the treatment of SMA. If apitegromab is approved by the FDA or EMA, the Company expects to initiate a commercial product launch in the applicable jurisdictions upon approval. The Company continues to develop apitegromab in SMA with its ongoing long-term extension ONYX trial and its Phase 2 OPAL trial in SMA patients under two years of age, which was initiated in the third quarter of 2025. Additionally, a Phase 2 study evaluating apitegromab in patients with FSHD is expected to initiate in mid-2026. In addition to the current intravenous (“IV”) formulation, the Company is developing a subcutaneous (“SC”) formulation of apitegromab. A Phase 1 study in healthy volunteers has been completed, demonstrating that SC apitegromab has favorable bioavailability and a comparable pharmacodynamic profile relative to IV administered apitegromab. Further development activities are ongoing, including planned FDA and EMA regulatory engagements. The Company’s clinical-stage pipeline also includes SRK-439, a novel, investigational, subcutaneously administered fully human anti-pro/latent myostatin antibody that has high inhibitory potency while maintaining selectivity towards myostatin. SRK-439 is being developed for the treatment of patients with rare, severe, and debilitating neuromuscular diseases.…