Replimune RP1 AdComm: Third Try in Melanoma, PDUFA Aug 2

Replimune Group (REPL) has a PDUFA date of August 2, 2026 for its resubmitted Biologics License Application for RP1 (vusolimogene oderparepvec) in combination with nivolumab for advanced melanoma in patients who progressed on anti-PD-1 therapy. This is the company’s third BLA submission after two Complete Response Letters, and the FDA has notified Replimune to expect an advisory committee meeting in late July.

The stock closed at $10.46 on July 23 with volume of 3.8 million shares, giving the company a market cap near $0.9 billion. This is a binary catalyst: approval could double or triple the stock. A third rejection would be devastating for a clinical-stage company with no revenue.

What RP1 is and why it has been rejected twice

RP1 is an oncolytic virus immunotherapy built on a proprietary strain of herpes simplex virus 1, engineered with a fusogenic protein and GM-CSF to maximize tumor killing and activate a systemic anti-tumor immune response. It is designed to be combined with checkpoint inhibitors like Bristol Myers Squibb’s Opdivo (nivolumab).

The FDA issued the first CRL in July 2025, citing inadequate evidence of effectiveness. A senior member of the original review team later stated publicly that clinical reviewers believed Replimune had provided adequate evidence of RP1’s contribution of effect, but FDA leadership disagreed. A second CRL followed in April 2026.

The June 2026 resubmission was classified as a complete Class 1 response, the most expedited review type. Replimune said the FDA has signaled a more collaborative posture following recent leadership changes at the agency.

The data behind the application

The BLA seeks accelerated approval based on the Phase 2 IGNYTE trial, which evaluated RP1 plus nivolumab in patients with confirmed progression on anti-PD-1 therapy. Key results:

• Objective response rate: 34%
• Median duration of response: 24.8 months
• RP1 holds Breakthrough Therapy and Priority Review designations

The contribution of effect question is central: the FDA’s past concern was whether RP1 adds meaningful benefit beyond nivolumab alone. The 34% response rate in a post-anti-PD-1 population, where nivolumab monotherapy has limited activity, is Replimune’s core argument.

What to watch next

The advisory committee meeting, expected before the August 2 PDUFA date, is the next catalyst. AdComm votes are not binding but heavily influence FDA decisions. If the panel recommends approval, the odds shift meaningfully. If the panel raises concerns about contribution of effect again, a third CRL becomes more likely.

The risk is clear: two prior rejections, a small Phase 2 dataset, and an agency that has already pushed back twice. Replimune is betting that new FDA leadership and the melanoma community’s support for expanded treatment options will tip the balance.

For context on how the FDA evaluates oncology drugs after rejection, see our GSK Jideytro approval coverage.

Source: Replimune IR press release | Dermatology Times