US FDA declines to approve Scholar Rock's muscle weakness drug; shares fall

Scholar Rock's shares fell 12% premarket after the FDA issued a complete response letter for its drug apitegromab, citing manufacturing issues at a third-party Catalent facility, not specific to the drug itself. Despite the setback for a product analysts project could generate nearly $2 billion in revenues by the early 2030s, the company plans to resubmit once Catalent resolves the identified problems, with analysts largely expecting eventual approval and a resolution within months.

Analysis

Scholar Rock (SRRK) experienced a 12% premarket share price decline following the U.S. FDA's issuance of a Complete Response Letter (CRL) for its key drug candidate, apitegromab. The rejection is not based on the drug's clinical data but stems from manufacturing issues identified at a third-party Catalent facility, a problem that has also recently impacted other firms like Regeneron. This development delays a critical asset for Scholar Rock, which analysts project could achieve nearly $2 billion in revenue by the early 2030s by targeting spinal muscular atrophy and the emerging market for muscle preservation alongside GLP-1 obesity treatments. Despite the immediate setback and market uncertainty, multiple analysts believe the probability of eventual approval remains unaffected, with BMO Capital Markets estimating a resolution to the manufacturing issues in under three months. The negative market reaction appears to be driven by the uncertainty of the timeline for resubmission rather than a fundamental reassessment of apitegromab's therapeutic or commercial potential.

Key Decisions for Investors

• The 12% share price decline, caused by a non-drug-specific manufacturing delay, may present a tactical opportunity for long-term investors who view the setback as temporary and the analyst-projected resolution timeline as credible.
• Investors should closely monitor communications from Scholar Rock and Catalent regarding the remediation of the FDA's findings, as the timeline for resolving these issues is now the primary catalyst for the stock.
• While the delay is likely transient, it introduces a period of uncertainty that could create a short-term overhang on the stock and provides a window for competitors in the muscle preservation space to advance, a risk factor to consider when assessing position size.