Replimune Shares Plunge Over 30% as FDA Staff Raise Concerns About Melanoma Drug

Shares of Replimune (NASDAQ: REPL) plummeted 30.5% in pre-open trading after the U.S. Food and Drug Administration (FDA) published critical briefing documents concerning the company's lead drug candidate. The documents were released ahead of a Cellular, Tissue, and Gene Therapies Advisory Committee (AdCom) meeting scheduled for July 30, 2026.

FDA Staff Highlights Key Concerns

The FDA reviewers raised significant questions about Replimune's biologics license application for vusolimogene oderparepvec (RP1), an investigational treatment for advanced cutaneous melanoma. The briefing documents identified several key issues with the supporting IGNYTE clinical study, including:

• Trial Design: Questions were raised about whether the single-arm trial design can adequately prove RP1's specific contribution to clinical benefit when used in combination with nivolumab.
• Patient Population: The agency noted that the heterogeneity of the patients enrolled in the trial limits the ability to interpret the results clearly.
• Regulatory Precedent: The FDA had previously recommended that Replimune conduct a randomized, controlled trial to better establish the drug's effectiveness.

A High-Stakes Regulatory History

The market's severe reaction is amplified by the fact that this is Replimune's third attempt to secure FDA approval for RP1 in this indication. The company has already received two Complete Response Letters (CRLs) for previous submissions.

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Investors are now pricing in a significant regulatory risk, as the company's decision to resubmit its application based on the same single-arm dataset, against prior FDA guidance, appears to have backfired. The selloff represents an acceleration of a de-risking trend that began in the prior trading session as investors grew cautious ahead of the AdCom review.

Implications for the Company's Future

The upcoming regulatory decision is a critical moment for Replimune. The company has warned in its own disclosures that another failure to obtain accelerated approval could force it to halt the RP1 melanoma development program entirely and consider a broad corporate restructuring.

With a cash runway expected to fund operations only into early 2027, the stakes are exceptionally high. The market will be closely watching the advisory committee's vote on July 30 and the FDA's final PDUFA goal date of August 2, which will likely determine the company's near-term trajectory.