An FDA advisory panel voted 10-3 that Replimune's RP1 showed clinically meaningful efficacy in advanced melanoma, overruling agency staff concerns about the single-arm trial design.
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Replimune wins 10-3 FDA panel vote for melanoma drug RP1
An FDA advisory panel voted 10-3 that Replimune Group's RP1 showed clinically meaningful efficacy in advanced melanoma, overruling agency staff who said the single-arm trial data was not interpretable.
"In my mind, this should be a therapy that's available to patients in the short term until the Phase 3 trial reads out," Hussein Tawbi, a melanoma specialist at MD Anderson Cancer Center, said.
About one-third of patients in the pivotal study saw some level of tumor response, and 15% achieved complete remission. The trial tested RP1 — an engineered viral immunotherapy injected directly into tumors — in combination with Bristol Myers Squibb's Opdivo in patients whose melanoma had progressed after prior immunotherapy. FDA scientists had argued in pre-meeting briefing documents that the lack of a control arm made it impossible to distinguish RP1's effect from Opdivo's, and that the survival analysis comparing responders to non-responders was unreliable.
The FDA is set to decide on approval by Aug. 2. The agency rejected RP1 twice before — once last year and again in April — citing reliance on the single-arm study. A confirmatory Phase 3 trial is expected to read out in late 2027. If approved, RP1 would serve patients with advanced melanoma who have limited options after treatment with Merck's Keytruda or BMS's Opdivo, a population with particularly poor response rates.
The panel's vote came after roughly 30 patients testified during a public hearing that they had benefited from RP1. Dissenting panelist Paul Chapman, chief medical research officer at Weill Cornell's Meyer Cancer Center, said he could not evaluate the data. "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," he said.
The positive vote increases the likelihood of FDA approval, though the split decision and agency staff's skepticism leave some uncertainty. Replimune's stock will be closely watched ahead of the Aug. 2 PDUFA date, with the confirmatory trial results in late 2027 serving as the next major catalyst.
This article is for informational purposes only and does not constitute investment advice.
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