Scholar Rock De-Risks Apitegromab SMA BLA and Enters Phase 2 in FSHD

Scholar Rock De-Risks Apitegromab SMA BLA and Enters Phase 2 in FSHD

Scholar Rock has made significant regulatory and clinical strides with apitegromab, its investigational monoclonal antibody designed to selectively inhibit the activation of myostatin. The company has successfully de-risked its regulatory pathway for spinal muscular atrophy (SMA) ahead of its September 30, 2026 PDUFA date, while expanding apitegromab's clinical pipeline into facioscapulohumeral muscular dystrophy (FSHD).

De-risking the SMA Filing Pathway

In September 2025, the FDA issued a Complete Response Letter (CRL) for the original apitegromab BLA in SMA due to manufacturing observations at Catalent Indiana LLC, a third-party fill-finish facility. Crucially, the observations were not specific to apitegromab, and no other issues regarding the drug's safety or efficacy were cited.

Scholar Rock resubmitted its BLA in March 2026, and in mid-August 2026, the company successfully de-risked its filing by completely removing the troubled Catalent Indiana facility from its global regulatory applications. Under FDA guidance, the review is now progressing solely with an alternate, established U.S.-based fill-finish facility.¹ The FDA's PDUFA action date remains on track for September 30, 2026, with a commercial supply of vials already prepared for an immediate launch upon approval.

Pipeline Expansion into FSHD

On September 2, 2026, Scholar Rock announced that the FDA granted both Fast Track and Orphan Drug designations to apitegromab for the treatment of facioscapulohumeral muscular dystrophy (FSHD). This regulatory milestone coincided with the commencement of participant dosing in the Phase 2 FORGE trial, a study evaluating the safety, tolerability, and efficacy of apitegromab in adults living with FSHD.