Massachusetts-based Replimune Group (Nasdaq: REPL) has announced plans to resubmit a Biologics License Application (BLA) to the US FDA for Rp1 (vusolimogene oderparepvec) in combination with nivolumab for the treatment of advanced melanoma in patients who have progressed on prior anti-PD-1 based therapy. The resubmission, described as imminent, follows what the company characterized as productive dialogue with the agency and represents a renewed attempt to secure approval for an oncolytic immunotherapy in a patient population with limited post-checkpoint options.
The BLA resubmission covers Rp1 used in combination with Bristol Myers Squibb's PD-1 inhibitor nivolumab, targeting patients with advanced melanoma who have confirmed progression on an anti-PD-1 containing regimen. Replimune said the FDA has indicated it will treat the resubmission as an urgent matter upon receipt and will prioritize its review, citing the significant unmet need in this patient population. No specific PDUFA date has been disclosed, though the expedited handling suggests a compressed review timeline relative to standard processes. The company said the resubmission would be filed within days of the May 29 announcement.
The BLA is supported by data from the IGNYTE clinical trial, which evaluated Rp1 combined with nivolumab in patients with advanced melanoma who had documented progression on an anti-PD-1 containing regimen. The trial enrolled a population with limited remaining treatment options, and results from IGNYTE formed the primary evidentiary basis for the original BLA submission. Specific response rate data and durability outcomes were not reiterated in the May 29 announcement, but the FDA's willingness to engage on a resubmission path and its stated intent to prioritize review suggests the agency views the clinical dataset as potentially actionable.
Mechanism and competitive context
Rp1 is engineered from a proprietary herpes simplex virus strain and is designed to selectively replicate within and kill tumor cells while simultaneously stimulating a systemic anti-tumor immune response. The construct incorporates a fusogenic protein (GALV-GP R⁻) and GM-CSF, intended to enhance immunogenic cell death and broaden immune activation beyond the injected lesion. This mechanism differentiates it from standard checkpoint inhibition by attempting to convert immunologically "cold" tumors into ones more responsive to immune attack.