Key Highlights
- FDA has now turned down Replimune’s RP1 melanoma immunotherapy twice
- The treatment was under evaluation as a combination therapy with Bristol Myers Squibb’s (BMY) Opdivo
- Regulatory concerns focused on trial design, with FDA deeming it not “adequate and well-controlled”
- Shares of REPL tumbled approximately 19% to $4.76, with trading paused twice for volatility
- Current share price represents a significant decline from the 52-week peak of $13.24
Replimune (REPL) has encountered another major regulatory hurdle as the FDA rejected its RP1 therapeutic candidate for the second consecutive time, maintaining its position on clinical trial methodology concerns.
The regulatory agency delivered a complete response letter denying approval for RP1, scientifically designated as vusolimogene oderparepvec, intended for administration with Bristol Myers Squibb’s (BMY) Opdivo in treating advanced melanoma patients previously exposed to anti-PD-1 therapies.
According to the correspondence addressed to Kari Jeschke, Replimune’s senior vice president of regulatory affairs, the FDA determined that supplementary exploratory data analyses failed to “alter” its previous assessment. The agency continued to view the RPL-001-16 trial as falling short of adequate and well-controlled investigation standards.
Notably, the FDA expressed no reservations regarding the drug’s safety profile — the central obstacle remains demonstrating sufficient efficacy through acceptable trial methodology.
This marks the second regulatory denial. The initial rejection occurred in July 2025, following Vinay Prasad’s appointment to lead the FDA’s Center for Biologics Evaluation and Research by two months. Following that setback, Replimune resubmitted its Biologics License Application in October 2025, which the agency accepted for consideration.
REPL shares declined approximately 19% to $4.76 following the announcement. Circuit breakers triggered two trading halts throughout the session due to excessive volatility. Based on Dow Jones Market Data, this price trajectory suggests the stock is heading toward its weakest closing level since October.
Trading at $4.76, shares now languish substantially beneath the 52-week high of $13.24.
Understanding RP1’s Mechanism
RP1 represents a bioengineered variant of Herpes Simplex Virus type 1 — the identical pathogen responsible for cold sores. Replimune has modified this virus to selectively replicate within malignant cells, destroying them upon replication while simultaneously stimulating an enhanced immune system response through white blood cell activation.
This therapeutic represents the flagship asset within Replimune’s RPx development platform, which concentrates on oncolytic immunotherapy approaches for solid tumor malignancies.
The biotechnology company currently maintains a market capitalization of approximately $393 million. Given its negative earnings — typical for clinical-stage biopharmaceutical companies developing their product pipelines — it lacks a traditional P/E ratio.
Internal Trading and Company Fundamentals
Replimune’s GF Score registers at 40 out of a possible 100 points, with profitability metrics scoring merely 1 out of 10. The company’s financial strength assessment achieves 6 out of 10.
During the most recent three-month period, company insiders disposed of $0.1 million in shares, with no documented insider purchases during the same timeframe.
Shares currently trade at $4.76, representing a substantial discount from the $13.24 yearly high achieved earlier in the fiscal year.
