Key Takeaways
- FDA issued a second complete response letter rejecting Replimune’s RP1 melanoma immunotherapy
- The treatment was under review for use with Bristol Myers Squibb’s (BMY) Opdivo
- Regulators maintained their position that the clinical trial lacks adequate controls
- REPL shares plummeted approximately 19% to $4.76, with trading halted twice
- Shares now trade significantly below the 52-week peak of $13.24
Replimune (REPL) has encountered its second regulatory roadblock, as the FDA maintains its position on fundamental concerns regarding the clinical trial methodology supporting the RP1 application.
The regulatory agency delivered a complete response letter refusing approval for RP1, scientifically designated as vusolimogene oderparepvec, intended for combination therapy with Bristol Myers Squibb’s (BMY) Opdivo in treating advanced melanoma patients previously treated with anti-PD-1 therapies.
In correspondence directed to Kari Jeschke, Replimune’s senior vice president of regulatory affairs, the FDA stated that supplementary exploratory analyses of the trial data failed to change its initial assessment. The agency continues to view the RPL-001-16 trial as falling short of adequate and well-controlled investigation standards.
Notably, the FDA expressed no safety reservations regarding the drug — the central issue remains the sufficiency of efficacy data.
This marks the second denial. The initial rejection occurred in July 2025, following Vinay Prasad’s appointment as head of the FDA’s Center for Biologics Evaluation and Research by two months. Replimune subsequently resubmitted its Biologics License Application, which gained acceptance for evaluation in October 2025.
REPL shares declined roughly 19% to $4.76 following the announcement. Volatility triggered two trading halts during the session. This decline positions the stock toward its weakest close since October, based on Dow Jones Market Data.
At current levels, REPL trades substantially below its 52-week peak of $13.24.
Understanding RP1 Technology
RP1 represents a genetically modified variant of Herpes Simplex Virus type 1 — the identical virus responsible for cold sores. Replimune engineered it to reproduce exclusively within tumor cells, causing cellular destruction while simultaneously stimulating enhanced immune activity from the body’s white blood cells.
The drug serves as the flagship candidate within Replimune’s RPx platform, dedicated to developing oncolytic immunotherapies targeting solid tumors.
The organization currently maintains a market capitalization of approximately $393 million. No P/E ratio exists due to negative earnings — a typical characteristic for clinical-stage biotechnology companies developing their product portfolios.
Insider Transactions and Company Fundamentals
Replimune’s GF Score registers at 40 out of 100, with profitability metrics scoring merely 1 out of 10. The company’s financial strength achieves a 6 out of 10 rating.
During the preceding three-month period, company insiders divested $0.1 million in stock, with zero reported acquisitions.
The stock currently trades at $4.76, markedly beneath the 52-week high of $13.24 reached earlier this year.
