Key Takeaways
- FDA issued second complete response letter denying approval for Replimune’s RP1 melanoma immunotherapy
- The treatment was under consideration for use with Bristol Myers Squibb’s (BMY) Opdivo
- Regulators maintained their position that the clinical trial lacked “adequate and well-controlled” design
- Shares of REPL plummeted approximately 19% to $4.76, with trading suspended twice due to extreme volatility
- The current price represents a significant decline from the 52-week peak of $13.24
Replimune (REPL) has encountered its second regulatory roadblock from the FDA, with the agency maintaining its previous objections regarding the clinical trial methodology supporting the RP1 application.
The regulatory body delivered a complete response letter rejecting vusolimogene oderparepvec, marketed as RP1, which was proposed as a combination therapy with Bristol Myers Squibb’s (BMY) Opdivo for treating advanced melanoma in patients who previously underwent anti-PD-1 therapy.
In correspondence directed to Kari Jeschke, Replimune’s senior vice president of regulatory affairs, the FDA indicated that supplementary exploratory data analyses failed to “alter” their original assessment. The agency determined that the RPL-001-16 clinical trial did not meet standards for an adequate and well-controlled investigation.
Notably, the FDA expressed no safety-related objections to the therapeutic candidate — the primary obstacle centers on demonstrating sufficient efficacy.
This marks the second time regulators have declined approval. The initial rejection occurred in July 2025, following Vinay Prasad’s appointment two months earlier to head the FDA’s Center for Biologics Evaluation and Research. The company submitted a revised Biologics License Application, which received acceptance for review in October 2025.
Shares of REPL declined roughly 19% to reach $4.76 following the announcement. The stock experienced two trading halts throughout the session as circuit breakers activated due to sharp price swings. According to Dow Jones Market Data, this pricing level tracks toward the lowest closing figure since October.
At the current valuation, REPL trades substantially beneath its 52-week peak of $13.24.
Understanding RP1’s Mechanism
RP1 represents a genetically modified variant of Herpes Simplex Virus type 1 — the identical virus responsible for cold sores. The company engineered this virus to selectively replicate within cancerous tumor cells, ultimately destroying them while simultaneously activating an enhanced immune response through the body’s white blood cell system.
This therapeutic candidate serves as the flagship product within Replimune’s RPx platform, which concentrates on developing oncolytic immunotherapies targeting solid tumor malignancies.
The biotechnology firm currently maintains a market capitalization of approximately $393 million. The company lacks a price-to-earnings ratio given negative earnings — a typical characteristic for clinical-stage biotechnology companies still developing their product portfolios.
Stock Trading Activity and Company Fundamentals
Replimune’s GF Score registers at 40 on a 100-point scale, with profitability metrics scoring merely 1 out of 10. The company’s financial strength receives a rating of 6 out of 10.
During the previous three-month period, company insiders disposed of $0.1 million in shares, while no insider purchases were documented.
The equity currently trades at $4.76, representing a substantial discount from the $13.24 high-water mark established earlier this year.
