9518 Background: Advanced melanoma has a high mortality rate; however, survival for patients (pts) treated with anti–PD-1–based therapy tends to plateau at 3–4 years, suggesting that pts alive at 3 years are likely to have prolonged benefit. This highlights the need for novel therapies that offer increased survival beyond 3-4 years. RP1 (vusolimogene oderparepvec) is an HSV-1–based oncolytic immunotherapy expressing GM-CSF and a fusogenic glycoprotein (GALV-GP-R − ). In the IGNYTE trial (data cu