FDA Panel Votes 10-3 That Replimune's RP1 Shows Meaningful Efficacy in Advanced Melanoma

The FDA's Cellular, Tissue, and Gene Therapies Advisory Committee (CTGTAC) voted 10–3 on July 30 that efficacy results from the phase 1/2 single-arm IGNYTE trial of Replimune's vusolimogene oderparepvec (RP1) combined with nivolumab (Opdivo) are "evaluable and clinically meaningful" in advanced melanoma patients who progressed on anti-PD-1 therapy, CancerNetwork reported. The vote came despite skeptical FDA briefing documents questioning whether the single-arm design could demonstrate substantial evidence of effectiveness.

A Long Road to the Table

RP1's biologics license application has already received two complete response letters — in July 2025 and April 2026 — making the panel's positive vote a critical step toward potential approval. The FDA's target action date for the application is August 2, 2026, and Replimune's stock more than doubled on the news. The committee also debated whether responses in non-injected lesions could be attributed to RP1's systemic mechanism rather than to a nivolumab rechallenge effect.

"The unmet need is substantial: patients with anti-PD-1-refractory advanced melanoma have historically faced a five-year survival rate below 25%," committee discussion noted.

What the Vote Means

Advisory committee votes are nonbinding, but the FDA typically follows them. If approved, RP1 would be the first oncolytic immunotherapy cleared for melanoma in this treatment-refractory setting, and a validation of Replimune's approach of engineering herpes-simplex-based vectors to prime the tumor microenvironment. The decision date of August 2 also lands days before the EU AI Act's enforcement deadline — a reminder that this has been one of the most consequential regulatory weeks of the year for both drugs and technology.