Key Takeaways
- The FDA has rejected Replimune’s melanoma treatment candidate, RP1, for the second time.
- The agency cited insufficient evidence of effectiveness from the Ignyte trial data and ongoing phase 3 trial results.
- Replimune’s stock price dropped approximately 20% in response to the rejection.
FDA Denies Replimune’s RP1 Application Again
Replimune’s melanoma treatment candidate, RP1, has faced a second setback as the FDA rejected its resubmitted application. Initially declined in July, the FDA concluded that the phase 1/2 Ignyte trial, evaluating RP1 in combination with Bristol Myers Squibb’s Opdivo, lacked adequate control and had a heterogeneous patient pool that complicated result interpretation.
In a complete response letter issued on April 10, FDA reviewers from the Office of Therapeutic Products and the Oncology Center of Excellence unanimously found the presented data insufficient to establish substantial evidence of effectiveness. This decision raises significant concerns regarding the future development of RP1. In a February SEC filing, Replimune indicated that a second rejection might lead it to reconsider the viability of continuing RP1’s development.
RP1, or vusolimogene oderparepvec, is an engineered herpes simplex virus that aims to enhance the patient’s immune response against cancer. Following the FDA’s rejection, Replimune’s stock price fell by about 20%, dropping from $5.91 to $4.76.
The FDA’s review included an analysis of data from the Ignyte trial, alongside new data from a phase 3 trial that Replimune included in its submission. Despite this fresh examination, the agency reiterated its initial stance, stating that the Ignyte trial data failed to meet necessary standards. Moreover, the FDA criticized the new trial data, noting that only 10% of the planned patient population had been treated, which did not provide sufficient insight.
Concerns were also raised about the absence of response duration data and difficulties interpreting progression-free survival metrics due to a lack of prespecification in the analysis. These factors contributed to the FDA’s ability to dismiss the additional data provided by Replimune.
The FDA has developed a reputation under the Trump administration for unexpected rejections, many attributed to Vinay Prasad, M.D., the former director of the Center for Biologics Evaluation and Research. In contrast, the initial rejection of RP1 was associated with Richard Pazdur, M.D., a recognized figure in oncology evaluations at the FDA who has since retired. The recent rejection was conducted by a different review team that did not oversee the first evaluation.
Replimune has not yet responded to inquiries following the latest rejection. The ongoing uncertainty surrounding RP1 raises vital questions about its future and the implications for Replimune’s broader pipeline.
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