A class action lawsuit has been filed on behalf of investors who bought Replimune Group, Inc. securities between October 20, 2025 and April 10, 2026, with shareholders having until October 5, 2026 to seek appointment as lead plaintiff. The case centers on Replimune’s statements after the U.S. Food and Drug Administration accepted the resubmission of its Biologics License Application (BLA, formal request to market a biologic drug) for RP1 in combination with nivolumab to treat advanced melanoma in patients whose disease progressed on an anti-PD-1 regimen. The complaint alleges the company failed to tell investors that FDA concerns about study design had not been resolved and that the resubmission relied in part on an early unplanned RP1-104 analysis involving 40 patients, or 10% of the planned 400-patient enrollment. On April 10, 2026, the FDA issued a Complete Response Letter (CRL, rejection requiring more work before approval), saying the evidence did not meet the evidentiary standard for approval and that exploratory analyses did not change its conclusion on the RPL-001-16 trial. Replimune shares fell $1.15, or 19.46%, to $4.76 before trading was halted on April 10, 2026, then dropped a further $3.06, or 64.29%, to $1.70 on April 13, 2026 after the company disclosed more detail about the FDA response.