The U.S. Food and Drug Administration is expected to make a decision by April 10 on Replimune’s advanced melanoma drug candidate, RP1, following a year marked by high-profile departures from key agency leadership roles.
The outcome of this decision is seen as important for the biopharma sector, as it may indicate how the FDA will approach future regulatory decisions. Cantor Fitzgerald analyst Li Watsek said many in the industry are watching closely, calling RP1’s review "a first indicator of how the FDA is going to act going forward." Watsek also noted ongoing discussions about political pressure and recent changes in FDA leadership.
RP1 was initially rejected last July when the FDA issued a complete response letter (CRL), surprising both analysts and Replimune CEO Sushil Patel. Patel said at the time that issues cited in the CRL were not previously raised during reviews. The rejection was reportedly influenced by senior officials Richard Pazdur and Vinay Prasad, with Pazdur objecting to approval despite consensus support within CBER.
The main concern highlighted by regulators involved variability among trial participants in terms of prior therapies and treatment duration. However, an open letter from 22 experts involved in RP1’s clinical trials argued that such heterogeneity reflects real-world scenarios and that requiring a control arm with Opdivo monotherapy would be "impractical, unacceptable and borders on the unethical." Analyst Robert Driscoll described the trial data as “very convincing,” noting higher response rates compared to previous studies with PD-1s alone.
Following protests from researchers, Replimune resubmitted its application last October. Analyst sentiment has since improved slightly; Driscoll estimated odds of approval at 60–70%, while market prices suggest about even chances. If approved, RP1 could generate peak annual sales of $800 million according to Watsek; if not approved, Replimune may shift focus away from RP1 entirely.
Prasad’s impending departure—and Pazdur’s earlier resignation—have increased expectations for a favorable outcome but have also created uncertainty about future regulatory approaches. “We need someone to come in that allows biotechs to be more confident in how regulatory decisions are being made,” Driscoll said.
