Replimune (REPL) Stock Falls 19% After FDA Rejects RP1 Melanoma Drug Application Again

TLDR

• The FDA rejected Replimune’s RP1 immunotherapy for advanced melanoma for the second time
• RP1 was being reviewed in combination with Bristol Myers Squibb’s (BMY) Opdivo
• The FDA again cited the clinical trial as not “adequate and well-controlled”
• REPL stock dropped ~19% to $4.76, triggering two trading halts due to volatility
• The stock is now trading well below its 52-week high of $13.24

Replimune’s (REPL) RP1 drug has now been rejected twice by the FDA, with the agency standing firm on its concerns about the clinical trial design used to support the application.

Replimune Group, Inc., REPL

The FDA issued a complete response letter declining to approve RP1, known as vusolimogene oderparepvec, for use alongside Bristol Myers Squibb’s (BMY) Opdivo in advanced melanoma patients who had previously received anti-PD-1 treatments.

In its letter to Replimune’s senior VP of regulatory affairs, Kari Jeschke, the FDA said additional exploratory analyses of trial data did “not alter” its earlier conclusion. The RPL-001-16 trial was deemed not an adequate and well-controlled clinical investigation.

The FDA raised no safety concerns with the drug — the sticking point remains efficacy evidence.

This is the second rejection. The first came in July 2025, two months after Vinay Prasad was appointed to lead the FDA’s Center for Biologics Evaluation and Research. Replimune resubmitted its Biologics License Application, which was accepted for review in October 2025.

REPL stock fell around 19% to $4.76 on the news. Trading was halted twice during the session due to volatility. The move puts the stock on pace for its lowest close since October, according to Dow Jones Market Data.

At that price, REPL sits well below its 52-week high of $13.24.

What Is RP1?

RP1 is a genetically engineered version of the Herpes Simplex Virus type 1 — the same virus behind cold sores. Replimune modified it to replicate only inside tumor cells, causing them to burst while also triggering a stronger immune response from the body’s white blood cells.

It’s the lead candidate in Replimune’s RPx platform, which focuses on oncolytic immunotherapies for solid tumors.

The company currently has a market cap of around $393 million. It carries no P/E ratio due to negative earnings — standard for a clinical-stage biotech still building its pipeline.

Insider Activity and Financial Health

Replimune’s GF Score stands at 40 out of 100, with profitability rated just 1 out of 10. Financial strength comes in at 6 out of 10.

Over the past three months, insiders sold $0.1 million worth of stock, with no reported purchases.

The stock is now trading at $4.76, well below the 52-week high of $13.24 set earlier in the year.

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