Replimune gets FDA Complete Response Letter

Replimune’s second bid to win United States approval for its melanoma drug RP1 failed on April 10, after the Food and Drug Administration sent the company another Complete Response Letter. (markets.businessinsider.com) The application covered RP1, or vusolimogene oderparepvec, used with Bristol Myers Squibb’s nivolumab for adults with advanced melanoma whose cancer had already progressed on an anti-programmed cell death protein 1 regimen. Replimune said the Food and Drug Administration kept its earlier position that the supporting trial was not enough to show effectiveness. (markets.businessinsider.com) A Complete Response Letter is the agency’s formal notice that it will not approve an application in its current form. Replimune had resubmitted the biologics license application in October 2025, and the agency set an April 10, 2026 action date before issuing this latest rejection. (dermatologytimes.com) RP1 is an oncolytic immunotherapy, a cancer treatment built from a modified herpes simplex virus type 1 that is injected into tumors to kill cancer cells and stir up a broader immune attack. Replimune has been trying to use that approach in melanoma patients who have few standard options left after failing earlier immunotherapy. (dermatologytimes.com) The regulatory fight has centered on IGNYTE, a single-arm study in 140 patients that reported a 33.6% overall response rate and a 15.0% complete response rate. The Food and Drug Administration said in 2025 that the trial’s design and mixed patient population made the results hard to interpret as substantial evidence of effectiveness. (targetedonc.com) That dispute has been running for months. The Food and Drug Administration first rejected the filing in July 2025, Replimune held a Type A meeting with the agency afterward, and by September 2025 the company said a forward path to accelerated approval still had not been determined. (targetedonc.com) Replimune said on April 10 that it “strongly disagrees” with the agency’s view of the data and plans to work with the Food and Drug Administration on possible next steps. Chief executive Sushil Patel said the company still believes the dataset that supported breakthrough therapy designation should be enough to make RP1 available to patients with advanced melanoma. (markets.businessinsider.com) Investors treated the letter as a major setback. Replimune shares fell nearly 20% on April 10 after the decision became public. (biospace.com) The company still has cash, but less room for error than it did a year ago. Replimune reported $269.1 million in cash, cash equivalents and short-term investments as of December 31, 2025, down from $483.8 million on March 31, 2025. (finanznachrichten.de) For now, RP1 remains unapproved in this melanoma setting, and Replimune is back where it was after the first letter in July 2025: trying to persuade regulators that its trial can support approval, or redesign the path forward. (fiercebiotech.com)