FDA rejects Scholar Rock’s SMA drug over manufacturing issues

The FDA denied approval of Scholar Rock’s muscle-targeted drug apitegromab for spinal muscular atrophy (SMA), citing manufacturing issues at a Catalent facility.

Why it matters: The rejection delays a potentially game-changing treatment for SMA, a condition that progressively weakens muscles and can be fatal in infants. Apitegromab showed promise in improving motor function where existing therapies fall short.

Backstory: Scholar Rock’s application was tied to a Catalent Indiana site that the FDA flagged during inspection. The facility, now owned by Novo Nordisk, also caused regulatory delays for other drugmakers. Scholar Rock plans to resubmit its application after issues are resolved.

Zoom in: SMA treatment has advanced rapidly since 2016 with gene-targeting and gene therapy options from Biogen, Novartis, and Roche, but these therapies don’t fully halt muscle decline. Scholar Rock's apitegromab, on the other hand, blocks myostatin, a protein that limits muscle growth, and showed strong Phase 3 results, improving motor function when used with standard treatment.

Big picture: The drug industry’s reliance on third-party manufacturers like Catalent can derail drug approvals, even when the drug itself performs well. Scholar Rock is aiming to become a leading rare disease biotech, and apitegromab, despite being likely delayed to 2026, could be its flagship product, with some analysts seeing it as a $2B-a-year product.