Replimune Presents New Analyses from the IGNYTE Study of RP1 plus Nivolumab in Anti-PD1 Failed Melanoma at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting

Replimune Group (REPL) presented data at ASCO 2025 highlighting positive results from its IGNYTE trial of RP1 plus nivolumab in anti-PD-1 failed melanoma patients, demonstrating a 32.9% objective response rate and encouraging overall survival rates. Notably, deep/visceral injections of RP1 showed numerically higher response rates compared to superficial injections, with manageable safety profiles in liver and lung lesions; additional biosafety analysis confirmed that standard disinfection procedures are sufficient for RP1 clean-up, minimizing transmission risks.

Analysis

Replimune Group presented compelling updated data from its IGNYTE clinical trial for RP1 (vusolimogene oderparepvec) in combination with nivolumab for anti-PD-1 failed melanoma at the ASCO 2025 Annual Meeting. The trial (n=140) demonstrated an objective response rate (ORR) of 32.9% using RECIST 1.1 criteria, with a notable complete response rate of 15.0%. Landmark overall survival (OS) rates were encouraging at 75.3% at one year, 63.3% at two years, and 54.8% at three years, with the median OS not yet reached, suggesting the potential for durable responses. A significant finding was the numerically higher ORR associated with deep/visceral injections of RP1 (42.9% for deep/visceral plus superficial injections and 40.9% for only deep/visceral injections) compared to superficial injections alone (29.8%). These deep injections, including directly into the liver and lung, were reported as generally well-tolerated, with few manageable organ-specific adverse events and no bleeding events post-liver injection. The data underscored RP1's systemic anti-tumor activity, evidenced by a ≥30% reduction in 93.6% of injected lesions and 79.0% of non-injected lesions, with similar response kinetics. Furthermore, 96.2% of non-injected visceral organ lesions in responding patients showed a reduction from baseline. Complementing these efficacy and safety findings, a separate biosafety analysis indicated that RP1 DNA is primarily detected at the injection site, live RP1 is rarely found elsewhere, and standard disinfection procedures are sufficient for clean-up, minimizing transmission risks and negating the need for additional biosafety protocols.

Key Decisions for Investors

• Investors should view the presented IGNYTE trial data as a positive development for Replimune, as the 32.9% ORR and robust overall survival figures in a difficult-to-treat anti-PD-1 failed melanoma population strengthen the clinical validation for RP1.
• The demonstration of numerically higher efficacy with deep/visceral RP1 injections (up to 42.9% ORR) and their manageable safety profile, including in liver and lung lesions, suggests broader therapeutic potential and a key differentiator for the product candidate.
• The favorable biosafety data, confirming minimal transmission risk and effective neutralization with standard disinfectants, alleviates practical concerns for clinical handling and could enhance RP1's adoptability upon potential approval, warranting continued observation of Replimune's clinical and regulatory advancements.