Replimmune’s oncolytic immunotherapy RP1 for advanced melanoma was rejected by the FDA, with the agency’s top cancer regulator Richard Pazdur reportedly overriding CBER staff consensus. Concerns focused on patient population heterogeneity and difficulty isolating RP1’s contribution from combination therapy with Opdivo. Experts have urged the FDA to reconsider, citing real-world applicability of trial design. The rejection caused a steep decline in Replimmune’s stock value and has sparked debate over the internal FDA review process.