Replimune Group, Inc. announced the topline results from the primary analysis of the IGNYTE clinical trial of RP1 plus nivolumab in anti-PD1 failed melanoma. The results by independent central review show one-third of patients receiving RP1 plus nivolumab responded to treatment, improving upon the investigator-assessed data presented at ASCO 2024, with all responses lasting greater than 6 months from baseline. The anti-PD1 failed melanoma cohort from the IGNYTE clinical trial includes 140 patients who received RP1 plus nivolumab after confirmed progression while being treated with at least 8 weeks of prior anti-PD1 therapy (+/- anti-CTLA-4).

The primary analysis by independent central review was triggered once all patients had been followed for at least 12 months. The topline results show the overall response rate was 33.6% by modified RECIST 1.1 criteria, the primary endpoint as defined in the protocol, and 32.9% by RECIST 1.1 criteria, an additional analysis requested by the FDA. Responses from baseline were highly durable, with all responses lasting more than 6 months and median duration of response exceeding 35 months.

The Company plans to submit the full primary analysis data from the anti-PD1 failed melanoma cohort including key secondary endpoint data and subgroups for presentation at an upcoming medical congress. RP1 combined with nivolumab continues to be well-tolerated, with mainly Grade 1-2 constitutional-type side effects, observed. Treatment-related adverse events associated with RP1 in combination with nivolumab were predominantly Grade 1-2 constitutional type events (> 5% of patients), including fatigue, chills, pyrexia, nausea, influenza-like illness, injection-site pain, diarrhea, vomiting, headache, pruritis, asthenia, arthralgia, myalgia, decreased appetite, and rash, with a low incidence of Grade 3-5 events.

Grade 4 events were one each of lipase increased, alanine aminotransferase increased, blood bilirubin increased, cytokine release syndrome, myocarditis, hepatic cytosis and splenic rupture. There were no Grade 5 events.