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 the agency's initial rejection of the drug earlier this year, sparking both controversy and renewed hope for patients with advanced melanoma.

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 resubmitted application includes additional "information, data and analyses" to address the concerns raised by the FDA during the previous review cycle.

RP1, Replimune's lead candidate, is an engineered strain of the herpes simplex virus designed to be administered in combination with Bristol Myers Squibb's checkpoint inhibitor Opdivo (nivolumab). This innovative approach aims to not only kill cancer cells directly but also stimulate the patient's immune system to target the tumor.

Clinical Data and Previous FDA Concerns

The resubmission is based on findings from a phase 1/2 trial involving 140 patients who had previously progressed on PD-1 inhibitor therapy. The study reported an objective response rate of 32.9%, a figure that Replimune believes demonstrates a strong risk-benefit profile for patients with limited treatment options.

However, the FDA's initial rejection in July 2025 cited concerns about the heterogeneity of the patient population, which the agency claimed made the trial results difficult to interpret adequately. This decision faced significant backlash, including criticism from The Wall Street Journal's editorial board, which argued that the FDA's approach was hindering the development of therapies for rare and deadly diseases.

Market Response and Future Outlook

The 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.

Replimune's CEO, Sushil Patel, Ph.D., expressed optimism about working closely with the FDA to expedite the review process. "RP1 plus nivolumab offers a strong risk benefit profile where there are few options for patients with advanced melanoma, who have progressed on PD-1 based therapy," Patel stated in the company's release.

As the pharmaceutical industry and patients await the FDA's decision in April 2026, the outcome of this review could have significant implications for the treatment landscape of advanced melanoma and potentially influence the regulatory pathway for other innovative cancer therapies.