Long-Term Results of the Randomized Phase III Trial EORTC 18991 of Adjuvant Therapy With Pegylated Interferon Alfa-2b Versus Observation in Resected Stage III Melanoma

PURPOSE: Adjuvant pegylated interferon alfa-2b (PEG-IFN-α-2b) was approved for treatment of resected stage III melanoma in 2011. Here, we present long-term follow-up results of this pivotal trial. PATIENTS AND METHODS: In all, 1,256 patients with resected stage III melanoma were randomly assigned to observation (n = 629) or PEG-IFN-α-2b (n = 627) for an intended duration of 5 years. Stratification factors were microscopic (N1) versus macroscopic (N2) nodal involvement, number of positive nodes, ulceration and tumor thickness, sex, and center. Recurrence-free survival (RFS; primary end point), distant metastasis-free survival (DMFS), and overall survival (OS) were analyzed for the intent-to-treat population. RESULTS: At 7.6 years median follow-up, 384 recurrences or deaths had occurred with PEG-IFN-α-2b versus 406 in the observation group (hazard ratio HR, 0.87; 95% CI, 0.76 to 1.00; P = .055); 7-year RFS rate was 39.1% versus 34.6%. There was no difference in OS (P = .57). In stage III-N1 ulcerated melanoma, RFS (HR, 0.72; 99% CI, 0.46 to 1.13; P = .06), DMFS (HR, 0.65; 99% CI, 0.41 to 1.04; P = .02), and OS (HR, 0.59; 99% CI, 0.35 to 0.97; P = .006) were prolonged with PEG-IFN-α-2b. PEG-IFN-α-2b was discontinued for toxicity in 37% of patients. CONCLUSION: Adjuvant PEG-IFN-α-2b for stage III melanoma had a positive impact on RFS, which was marginally significant and slightly diminished versus the benefit seen at prior follow-up (median, 3.8 years). No significant increase in DMFS or OS was noted in the overall population. Patients with ulcerated melanoma and lower disease burden had the greatest benefit.