FDA staff reiterate concerns about Replimune skin cancer treatment ahead of advisory meeting

FDA staff reiterated concerns that Replimune lacks adequate data for its skin cancer drug, RP1, ahead of an advisory meeting. This is the company's third approval attempt for the "highly controversial" drug. The FDA questions the single-arm trial design used, arguing it's insufficient to prove efficacy. Replimune counters that a randomized trial would be unethical for patients who have stopped responding to other treatments.

FDA concerns about Replimune trial

• ▪The U.S. Food and Drug Administration (FDA) argued that Replimune's study is insufficient to properly evaluate the drug's efficacy.
• ▪FDA staff released briefing documents with their concerns on July 28, 2026, ahead of an advisory committee meeting.
• ▪FDA regulators have reiterated concerns that Replimune lacks adequate data to support the approval of its investigational skin cancer treatment, RP1.
• ▪The FDA questioned whether the locally injected treatment has systemic benefits.

Single-arm study design issues

• ▪The FDA has taken issue with the single-arm trial that Replimune is relying on for its drug's approval.
• ▪The trial involved patients, who had already tried a PD-1 inhibitor, taking Replimune's drug RP1 in combination with the PD-1 inhibitor Opdivo.

Replimune's ethical defense

• ▪Replimune argued there is no evidence that continued anti-PD-1 monotherapy benefits patients whose cancer has stopped responding to it.
• ▪Replimune stated in its briefing document that conducting a randomized, placebo-controlled study would not be "feasible or ethical."

Third approval attempt

• ▪Replimune's investigational skin cancer drug, RP1, is described as "highly controversial."
• ▪The biotech company Replimune is making its third attempt to seek regulatory clearance for its drug, RP1.

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