Replimune’s oncolytic virus therapy for advanced melanoma was rejected by the FDA for a second time after the company resubmitted an application following earlier concerns. The agency said Replimune did not resolve issues with study results that drove the first complete response letter. The denials keep the debate over regulatory flexibility in focus, particularly for complex viral therapies where the evidentiary bar and trial execution details can determine whether future submissions gain traction. The timeline—an April 10 PDUFA date—underscored how quickly biotech strategies can be reset after regulatory feedback. For investors and competitors, the second rejection signals that changes required by the agency are not limited to minor protocol clarifications. It raises the likelihood that Replimune must generate additional data or restructure key aspects of its clinical package before the program can move forward. Overall, the decision becomes another datapoint in how FDA is handling evolving standards for immuno-oncology biologics built on engineered platforms.