Replimune Group faces investor litigation after the U.S. Food and Drug Administration first rejected its Biologics License Application for RP1, or vusolimogene oderparepvec, with Bristol Myers Squibb's Opdivo, also known as nivolumab, for advanced melanoma on April 10, 2026 and later questioned supporting data in July 28 briefing documents. A class action filed on behalf of investors who bought securities between October 20, 2025 and April 10, 2026 alleges the company did not disclose unresolved FDA study-design concerns and that its October 2025 resubmission relied in part on an early unplanned RP1-104 analysis of 40 patients, or 10% of planned enrollment; shareholders have until October 5, 2026 to seek lead-plaintiff status. Replimune shares fell $1.15, or 19.46%, to $4.76 before a trading halt on April 10, then another $3.06, or 64.29%, to $1.70 on April 13 after more detail on the Complete Response Letter, and later dropped $3.28, or 38.01%, to $5.35 on July 28 after the FDA said the IGNYTE response assessment "confounds interpretation of the reported efficacy results and limits FDA's ability to verify the reported results." On Aug. 6, 2026, Pomerantz LLP said it was separately investigating whether Replimune and certain officers or directors engaged in securities fraud or other unlawful business practices.