Replimune Group, Inc. (REPL), a clinical-stage biotechnology company, announced that the company received a complete response letter or CRL from the U.S. Food and Drug Administration (FDA) for its Biologics License Application for RP1 (Vusolimogene oderparepvec) in combination with Nivolumab for the treatment of advanced melanoma.
Following the news, REPL fell 55.67% to $2.13 in the overnight market.
Earlier in June 2025, the FDA had already issued a CRL for Replimune, stating that the prespecified response rate in the RPL-001-16 trial for RP1, though numerically higher, cannot be adequately interpreted due to heterogeneity in the RPL-001-16 trial patient population, including the types of prior therapy received.
The FDA also said earlier that the RPL-001-16 trial is not considered an adequate and well-controlled clinical investigation that provides substantial evidence of the required effectiveness.
Following that, in the Type A meeting, Replimune noted that after the testimony from the melanoma experts, the agency did not raise further concerns about the heterogeneity of the patient population in IGNYTE and acknowledged that randomising patients to an anti-PD1-only arm in the confirmatory study was not feasible.
And based on the suggestion, the company submitted a proposal for a descriptive analysis from IGNYTE-3 with data, including median progression-free survival on RP1 plus nivolumab of 30.6 months in responding patients, compared to 4.4 months on their prior PD-1-based regimen.
Also, in the IGNYTE trial, patients with confirmed progression on an anti-PD-1-based regimen who received RP1 plus nivolumab had a 34% response rate with a median duration of 24.8 months, with a favourable safety profile.
During the meeting with the FDA, several points related to the tumour assessment methodology were raised, and the firm says that, as requested by the FDA, responses in IGNYTE were assessed using RECIST 1.1 without modifications.
Melanoma is the fifth most common cancer, with approximately 112,000 new cases estimated in the U.S. in 2026, and the most lethal form of skin cancer, accounting for nearly 8,500 deaths annually, according to the firm.
Feeling disappointed with the CRL, Sushil Patel, PhD, CEO of Replimune, said that the FDA has not exercised regulatory flexibility to meet patients' needs, despite data supporting strong efficacy and a favourable safety profile.
With no safety or manufacturing concerns noted, it appears the FDA strongly disagreed with the trial design and the evidence of efficacy.
Commenting on the FDA decision, Replimune emphasised the commercial and operational impact, stating that "as we previously communicated, without timely accelerated approval, the development of RP1 will not be viable," and added that the therapy may not reach patients "not because the medicine failed, but because the system did."
Apart from RP1, the firm's other development programs include RP2 and RP3, which are investigational oncolytic immunotherapies currently being evaluated in clinical trials across solid tumours, including melanoma, liver cancer.
REPL has traded between $2.6800 and $13.24. The stock closed Friday's trade at $4.76, down 19.46%.
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