Replimune Group's RP1 (vusolimogene oderparepvec), in combination with Bristol Myers Squibb’s Opdivo (nivolumab), has received priority review from the FDA for the treatment of adult patients with advanced melanoma who have failed prior anti-PD-1 therapy. This regulatory milestone accelerates the potential approval of a novel therapeutic approach for a challenging patient population.
The FDA has set a target decision date of July 22, 2025. Notably, the agency has indicated that it does not currently plan to hold an advisory committee meeting related to the BLA, suggesting confidence in the data submitted. The BLA is based on data from the IGNYTE study, which evaluated the combination in patients with melanoma who had progressed on anti-PD-1 therapy.
IGNYTE Study Results
The IGNYTE study demonstrated a 33.6% overall response rate (ORR) by modified RECIST 1.1 criteria, the primary endpoint, and 32.9% by RECIST 1.1 criteria. Responses were durable, with all responses lasting more than six months and the median duration of response exceeding 35 months. The combination therapy was generally well-tolerated, with mainly grade 1-2 constitutional-type side effects.
Breakthrough Therapy Designation
RP1 had previously been granted Breakthrough Therapy designation by the FDA in combination with Opdivo for this indication. This designation is reserved for therapies that demonstrate the potential for substantial improvement over existing treatments for serious conditions, and it allows for more intensive FDA guidance and organizational support during the drug development process.
Ongoing Phase III Trial
Replimune is currently enrolling patients in the confirmatory phase III IGNYTE-3 study. This trial is evaluating RP1 in combination with Opdivo in advanced melanoma patients who have progressed on anti-PD1 and anti-CTLA-4 therapy, or who are not eligible for anti-CTLA-4 treatment. The global study plans to enroll patients at over 100 sites.
RP1 Mechanism of Action
RP1 is based on a proprietary strain of herpes simplex virus, engineered and genetically armed with a fusogenic protein (GALV-GP R-) and GM-CSF. This design aims to maximize tumor killing potency, enhance the immunogenicity of tumor cell death, and activate a systemic anti-tumor immune response.
Broader Development Program
Beyond melanoma, Replimune is investigating the RP1/Opdivo combination in other cohorts of the IGNYTE study for non-melanoma skin cancer indications. RP1 is also being evaluated as a monotherapy in solid organ transplant recipients with skin cancers, and in combination with Libtayo for cutaneous squamous cell carcinoma. Replimune's pipeline includes RP2, being evaluated for uveal melanoma and hepatocellular carcinoma (HCC).
