FDA Rejects Scholar Rock's Spinal Muscular Atrophy Drug Due to Manufacturing Site Issues

In a setback for patients with spinal muscular atrophy (SMA), the U.S. Food and Drug Administration (FDA) has declined to approve Scholar Rock's investigational myostatin blocker apitegromab. The rejection, announced on Tuesday, stems from problems at a third-party manufacturing facility rather than concerns about the drug's efficacy or safety.

Manufacturing Woes at Novo Nordisk-Owned Facility

The FDA's decision hinges on observations made during a routine inspection at Catalent Indiana LLC, a fill-finish site recently acquired by Novo Nordisk in December 2024. Scholar Rock emphasized that these observations were not specific to apitegromab, suggesting broader quality control issues at the facility.

This rejection follows a troubling pattern of manufacturing problems at the Catalent site. Last month, STAT News revealed an FDA investigation report detailing poor quality control, substandard equipment maintenance, and alarming contamination issues at the facility. The report cited instances of "atypical extrinsic particles" such as cat hair, bacterial contaminations, and pest infestations, with some problems dating back to June 2022.

Novo Nordisk, responding to these findings, stated they are taking the issues "seriously" and implementing "appropriate actions" to address them "promptly and holistically."

Impact on Scholar Rock and Other Pharmaceutical Companies

The FDA's decision has had an immediate impact on Scholar Rock's market performance, with shares dropping 12.5% in pre-market trading on Tuesday. CEO David Hallal announced that the company is working closely with Catalent Indiana to address the FDA's concerns and plans to resubmit the application "as soon as possible," though no specific timeline has been provided.

Scholar Rock isn't the only pharmaceutical company affected by issues at the Catalent facility. Regeneron recently announced delays in FDA decisions for its high-dose formulation of Eylea, pushing expected rulings into the fourth quarter of 2025 due to problems at the same manufacturing site.

Apitegromab's Potential in SMA Treatment

Despite the setback, apitegromab's clinical data remains promising. The drug's application was supported by results from the Phase III SAPPHIRE study, which demonstrated significant improvements in motor function for SMA patients. Benefits were observed as early as 8 weeks into treatment and continued to improve through 52 weeks of follow-up.

The FDA's rejection letter did not cite any concerns regarding apitegromab's efficacy or safety, which BMO Capital Markets analysts consider a "mild positive" for Scholar Rock. This development could potentially "mitigate further concerns" surrounding the rejection and bodes well for the drug's future prospects once manufacturing issues are resolved.