FDA Accepts Replimune’s RP1 BLA Resubmission for Advanced Melanoma

Replimune Group has reached another key regulatory milestone after the U.S. Food and Drug Administration (FDA) accepted the resubmission of its Biologics License Application (BLA) for RP1 (vusolimogene oderparepvec) in combination with nivolumab for adults with advanced melanoma that has progressed following anti-PD-1 treatment.

The FDA classified the application as a complete Class 1 resubmission and assigned a Prescription Drug User Fee Act (PDUFA) target action date of August 2, 2026. The agency also informed the company that it expects to convene an advisory committee meeting in late July. The resubmission follows the FDA’s issuance of a Complete Response Letter (CRL) in the month of April 2026. 

The resubmission supports accelerated approval based on findings from the Phase 1/2 IGNYTE clinical trial (NCT03767348), which evaluated RP1 plus nivolumab in patients with advanced melanoma whose disease had progressed despite prior anti-PD-1-containing therapy. This patient population has limited treatment options and generally faces poor clinical outcomes after checkpoint inhibitor failure.

RP1 Combines Oncolytic Viral Therapy with Immunotherapy

RP1 is an investigational oncolytic immunotherapy derived from a proprietary strain of herpes simplex virus type 1 (HSV-1). The virus has been genetically engineered to express granulocyte-macrophage colony-stimulating factor (GM-CSF) and a GALV-GP R⁻ fusogenic protein, enhancing direct tumor cell destruction while promoting a broader anti-tumor immune response.

The therapy is administered in combination with the PD-1 inhibitor nivolumab to stimulate both local and systemic immune activity against cancer cells. The strategy aims to overcome resistance in tumors that no longer respond to immune checkpoint blockade.

IGNYTE Trial Supported Accelerated Approval Application

The BLA resubmission is supported by data from the IGNYTE trial, which enrolled patients with advanced melanoma that had confirmed progression on prior anti-PD-1-based therapy. The study evaluated the efficacy and safety of RP1 administered together with nivolumab in a population with substantial unmet medical need.

Although the company did not disclose new efficacy or safety results with this regulatory update, previously reported IGNYTE data demonstrated durable anti-tumor activity that formed the basis of the accelerated approval application. The FDA’s acceptance indicates that the agency considers the resubmission complete and suitable for substantive review.

Leadership Highlights Urgent Need for New Treatment Options

Chief Executive Officer Sushil Patel, Ph.D., said the FDA’s expedited review reflects the urgent need for additional therapies for patients with advanced melanoma who have exhausted standard immunotherapy. He added that the company looks forward to discussing the overall benefit-risk profile of RP1 with the advisory committee before the agency reaches its final decision.

Advanced Melanoma Remains a Major Clinical Challenge

Melanoma is the fifth most commonly diagnosed cancer in the United States, with an estimated 112,000 new cases expected in 2026. It remains the deadliest form of skin cancer, causing approximately 8,500 deaths each year. Once melanoma spreads beyond its primary site, treatment becomes substantially more difficult. While immune checkpoint inhibitors have transformed care, nearly half of treated patients either fail to respond or eventually develop disease progression, underscoring the need for effective therapies after PD-1 inhibitor failure.

Next Regulatory Milestones

The FDA is expected to hold an advisory committee meeting in late July 2026 before issuing its regulatory decision on August 2, 2026. If approved under the accelerated approval pathway, RP1 combined with nivolumab could become a new treatment option for patients with advanced melanoma whose disease progresses after anti-PD-1 therapy, addressing a critical unmet need in melanoma management.

Reference

Replimune Announces FDA Acceptance of RP1 Biologics License Application Resubmission for Advanced Melanoma | Replimune Group Inc.