FDA Accepts Replimune's Melanoma Drug Resubmission, Setting April 2026 Decision Date

The U.S. Food and Drug Administration (FDA) has accepted Replimune's resubmission of its biologics license application for RP1, a novel melanoma treatment. This development comes after a high-profile rejection earlier this year, sparking renewed hope for the biotech company and patients alike.

Resubmission Details and FDA Timeline

Replimune announced on October 20, 2025, that the FDA has set a target decision date of April 10, 2026, for RP1. The drug, an engineered strain of the herpes simplex virus, is designed to be used in combination with Bristol Myers Squibb's checkpoint inhibitor Opdivo (nivolumab). RP1's mechanism of action involves directly killing cancer cells while simultaneously stimulating an immune response against the tumor.

The resubmission includes additional "information, data and analyses" to address the FDA's previous concerns. Replimune's CEO, Sushil Patel, Ph.D., expressed the company's commitment to working closely with the agency to expedite the review process.

Previous Rejection and Clinical Data

The FDA's initial rejection in July 2025 cited issues with the heterogeneity of the patient population in Replimune's phase 1/2 trial. This decision faced significant public backlash, including criticism from The Wall Street Journal's editorial board.

The original application was based on a study involving 140 patients who had previously progressed on PD-1 inhibitor therapy. The trial reported an objective response rate of 32.9%, which Replimune believes demonstrates a strong risk-benefit profile for patients with limited treatment options.

Market Response and Future Outlook

News of the FDA's acceptance of the resubmission had an immediate and dramatic effect on Replimune's stock, which surged nearly 100% to close at $8.94 per share on the day of the announcement.

As the April 2026 decision date approaches, all eyes will be on Replimune and the FDA. The outcome could have significant implications not only for patients with advanced melanoma but also for the broader landscape of cancer immunotherapy development.