LAUSR

2512 Background: Since 2015, ipilimumab (Ipi) is an approved treatment for stage III melanoma based on a significantly (P=0.0013) prolonged recurrence-free survival (RFS) (Eggermont et al, Lancet Oncology, 2015). At a median follow-up of 5.3 years, RFS (HR=0.76) and distant metastasis-free survival (DMFS) (HR=0.76), assessed by an IRC, and overall survival (OS) (HR=0.72) were prolonged in the Ipi group as compared to the placebo (Pbo) group (Eggermont et al, NEJM, 2016), despite a 53.3% (Ipi) vs 4.6% (Pbo) treatment discontinuation rate due to adverse events. Methods: In this randomized double-blind trial, eligible patients (pts) included those ≥18 yrs of age who underwent complete resection of stage III cutaneous melanoma (excluding lymph node metastasis ≤1 mm or in-transit metastasis). 951 pts were randomized (stratified by stage and region) 1:1 to Ipi 10 mg/kg (n=475) or placebo (Pbo, n=476) q3w for 4 doses, then every 3 mos for up to 3 yrs until completion, disease recurrence, or unacceptable toxicity. Here, we report the comparison between the Ipi and Pbo groups regarding the long-term efficacy outcomes using the local investigator assessments. Results: Overall, 20%/44%/36% of pts had AJCC-7 stage IIIA/IIIB/IIIC, 42% ulcerated primary, and 58% macroscopic lymph node involvement. Median follow-up was 6.9 yrs. The RFS, DMFS and OS benefit observed in the Ipi group was long-lasting (almost 10% difference at 7 years) and consistent across subgroups: no significant predictive factors could be detected. Conclusions: In this phase III trial, Ipi, administered at 10 mg/kg, as adjuvant therapy provided, at a 6.9 yr median follow-up, a sustained improvement in the RFS, DMFS, and OS long-term results in patients with high-risk stage III melanoma. Clinical trial information: NCT00636168. [Table: see text]