Full Breakdown
FDA Advisory Panel Backs Replimune’s RP1 for Advanced Melanoma
8/1/2026, 3:12:21 PM
Core Event – Advisory Committee Vote
On July 31, 2026, the FDA’s Cellular, Tissue, and Gene Therapies Advisory Committee (CTGTAC) voted 10-3 to deem the efficacy results from Replimune’s IGNYTE trial of RP1 (vusolimogene oderparevec) plus nivolumab “evaluable and clinically meaningful.” The panel’s recommendation raises the likelihood of accelerated approval, which the FDA must decide by August 2, 2026.
Background & Context – RP1 Development and Prior FDA Rejections
RP1 is an oncolytic herpes-simplex-virus immunotherapy injected into tumors and combined with Bristol Myers Squibb’s PD-1 inhibitor Opdivo. It targets patients with unresectable or metastatic cutaneous melanoma who have progressed after anti-PD-1 therapy. Replimune’s Biologics License Application was declined in April 2026 and July 2025 because the single-arm IGNYTE study was deemed insufficiently controlled. After alignment meetings, the same data were resubmitted in June 2026, prompting the advisory panel meeting.
Data & Statistics – IGNYTE Trial Results and Disputed Figures
- Objective response rate (ORR): Company reported 33.6 % (47/140); FDA reviewers calculated 15.7 % (22/140).
- Complete responses: About 15 % of patients.
- Median duration of response: 24.8 months (company) vs 14.1 months (FDA).
- Overall survival: Company cited a median of 32.9 months with 47 % alive at three years; FDA staff called the data “not interpretable.”
- Safety: FDA identified several serious, potentially life-threatening adverse events possibly related to RP1, though panel members said the overall toxicity profile appeared preferable to existing alternatives.
Official Statements & Responses
Replimune CEO Sushil Patel said the company is “encouraged by today’s outcome.” FDA acting deputy director Megha Kaushal said the agency will weigh the committee’s recommendation, the public hearing, and the “totality of the scientific discussion” before deciding.
Conflicting Reports & Gaps – Divergent Interpretations of the Same Trial
The key discrepancy is the ORR calculation (33.6 % vs 15.7 %). Median response duration also differs markedly. FDA staff questioned whether tumor shrinkage in non-injected lesions could be attributed to RP1 or to nivolumab rechallenge, noting the lack of a control arm limits attribution.
Why It Matters – Unmet Need in PD-1-Refractory Melanoma
Patients who have progressed after anti-PD-1 therapy have few options. Existing alternatives, such as Iovance’s T-cell therapy Amtagvi, require intensive lymphodepletion. RP1 would offer an intratumoral, virus-based approach without extensive conditioning, potentially expanding access.
What’s Next – FDA Decision Timeline
The FDA’s target action date is August 2, 2026. The agency will consider the advisory committee’s recommendation, public testimony, and its own assessment before issuing a final decision on accelerated approval.
