Analysis of surrogate gene expression markers in peripheral blood of melanoma patients to predict treatment outcome of adjuvant pegylated interferon alpha 2b (EORTC 18991 side study)

We analysed mRNA levels of interferon response genes (ISG15, STAT1, CXCL10) of inhibitors of the JAK/STAT pathway (STAT3, SOCS1, SOCS3) and of cytokines (TNF alpha, IL10, TGF1) in peripheral blood of 91 stage III melanoma patients enrolled in EORTC 18991 trial to find biomarkers indicative for disease stage and predictive for efficacy of pegylated interferon alpha-2b (PEG-IFN alpha-2b) therapy. mRNA levels were analysed at baseline and after 6 months. Univariate and multivariate analyses were performed to estimate the prognostic and predictive role of mRNA levels for distant metastasis-free survival (DMFS) and relapse-free survival (RFS). Compared to healthy controls, melanoma patients showed significantly higher TGF beta 1 mRNA levels. In a multivariate model, increasing SOCS1 and SOCS3 mRNA levels were associated with worse RFS (P = 0.02 and P = 0.04, respectively) and DMFS (P = 0.05 and P = 0.05, respectively) due to negative correlation between, respectively, SOCS1/SOCS3 mRNA levels and ulceration or Breslow thickness. No impact of PEG-IFN alpha-2b on mRNA levels was observed except for ISG15 mRNA levels, which decreased in the treatment arm (P = 0.001). It seems that patients with a decrease > 60 % of ISG15 mRNA levels during 6 months PEG-IFN alpha-2b had inferior outcome.