Replimune (REPL) Stock: Biotech Shares Surge 100% on Regulatory Breakthrough

TLDR

• FDA accepted Replimune’s resubmitted Biologics License Application for RP1 combined with Bristol Myers Squibb’s Opdivo to treat advanced melanoma
• The agency set April 10, 2026 as the decision deadline for the drug’s approval
• Replimune stock doubled on Monday, rising 100% to $9.00 per share in late-session trading
• The resubmission followed a complete response letter the FDA sent in June 2025, which rejected the initial application
• RP1 targets melanoma patients who have progressed on PD-1 based therapy, where treatment options are limited

Replimune Group stock doubled on Monday, closing at $9.00 per share after rising 100% in late-session trading. The biotech company announced the FDA accepted its resubmitted Biologics License Application for RP1.

Replimune Group, Inc., REPL

The regulatory agency set April 10, 2026 as the decision deadline. This timeline follows the standard Class II resubmission process under the Prescription Drug User Fee Act.

The announcement came before market open on Monday. The news erased months of uncertainty that had weighed on the company’s share price since June.

RP1 works in combination with Bristol Myers Squibb’s Opdivo to treat advanced melanoma. The therapy targets patients who have progressed on PD-1 based treatments, where options are limited.

Replimune CEO Sushil Patel described the combination therapy as offering a strong risk benefit profile. He pointed to the limited alternatives available for this patient population.

The path to this acceptance wasn’t smooth. The FDA sent Replimune a complete response letter in June 2025, essentially rejecting the initial application.

The Road to Resubmission

A complete response letter means the regulatory agency won’t approve a drug application as submitted. Companies must address the FDA’s concerns and provide additional information.

Replimune held a meeting with the FDA in mid-September to discuss the feedback. At the time, the meeting appeared inconclusive to market observers.

The company worked to compile additional information, data and analyses requested by the agency. Monday’s acceptance indicates the FDA considers this a complete response to the June letter.

The agency raised concerns about the IGNYTE trial’s effectiveness during the review process. Questions about patient population heterogeneity affected how regulators interpreted the results.

JPMorgan downgraded Replimune’s stock rating from Neutral to Underweight earlier in the process. The firm acknowledged compelling data for RP1 while expressing concern about regulatory hurdles.

H.C. Wainwright maintained its Neutral rating on the company throughout the review period. Analyst perspectives remained cautious given the uncertainty.

What RP1 Does

RP1, also known as vusolimogene oderparepvec, represents Replimune’s lead product candidate. The drug is based on a proprietary strain of herpes simplex virus.

The company engineered the virus with a fusogenic protein and GM-CSF. This design aims to kill tumor cells while activating an immune response against cancer.

Replimune built the therapy using its RPx platform. The platform relies on HSV-1 backbone technology for developing oncolytic immunotherapies.

The stock had traded as low as $2.68 and as high as $17.00 over the past 52 weeks. Monday’s surge brought the market cap to $698 million.

Trading volume reached 220,246 shares on Monday. The average volume typically sits at 11,611,226 shares, indicating the day’s activity was lighter than usual despite the price movement.

The company was founded in 2015 and operates as a clinical stage biotechnology firm. Replimune is based in Woburn, Massachusetts.

The company maintains a current ratio of 6.94x, showing cash reserves exceeding debt obligations. This liquidity position provides runway as the company awaits the FDA’s decision next April.

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