The vote raises the chance the FDA will approve RP1, an engineered viral immunotherapy, ahead of an Aug. 2 decision deadline
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Replimune Group announced that an FDA advisory panel voted 10-3 on Thursday in favor of its experimental melanoma treatment, RP1, increasing the likelihood of approval after two prior rejections. The committee determined that efficacy results from the company's IGNYTE clinical trial were evaluable and clinically meaningful, according to BioPharma Dive.
The FDA faces an Aug. 2 deadline to render a final decision on RP1. While the agency typically gives weight to its advisory panels' conclusions, it retains full authority to reach a different outcome, according to STAT News.
Replimune is seeking approval for RP1 — also known as vusolimogene oderparepvec — in combination with Bristol Myers Squibb $BMY's immunotherapy Opdivo for patients whose melanoma has progressed after treatment with drugs such as Merck $MRK & Co.'s Keytruda or Bristol Myers Squibb's Opdivo. The company said roughly one-third of patients in the IGNYTE study responded to the treatment, with 15% achieving complete remission, and that the median duration of response stretched close to two years.
Before the meeting, FDA scientists raised objections in briefing documents, contending that the trial's single-arm structure prevented any reliable distinction between the contributions of RP1 and those of Opdivo, according to The Wall Street Journal. That limitation, agency reviewers argued, fatally undermined the survival data pitting those who responded to the treatment against those who did not.
Several panelists acknowledged the data were difficult to interpret. "I just don't even understand the data. I don't know what the response rate is. I don't know what to compare it to," said Paul Chapman, chief medical research officer of Weill-Cornell's Meyer Cancer Center, who voted against RP1, according to BioPharma Dive. But the majority concluded that the results were meaningful enough given the lack of treatment options for this patient group. "In my mind, this should be a therapy that's available to patients in the short term until the Phase 3 trial reads out," said Hussein Tawbi, a melanoma specialist at MD Anderson Cancer Center. More than 30 people spoke in favor of the drug during a public comment period at the meeting, including several who said they had taken the medication, according to the Wall Street Journal.
The vote capped a prolonged regulatory saga. Replimune reached an agreement with the FDA to pursue a third submission following a period of significant friction with regulators. Replimune first applied for approval in November 2024, was rejected in July 2025, then rejected again in April 2026. A third submission was allowed in June, with the FDA treating it as a priority review.
Earlier this week, the FDA released briefing documents warning that some results from the IGNYTE study were "not interpretable," sending Replimune stock down more than 30%. Trading in the stock was halted on Thursday during the advisory committee meeting, a standard practice around such panels.
Another rejection from the FDA would leave Replimune sidelined until data from a confirmatory Phase 3 trial arrive, which is not anticipated until late 2027, before any fresh application could be filed.
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