Predictive utility of circulating methylated DNA in serum of melanoma patients receiving biochemotherapy

Purpose Currently, no validated blood-based assays accurately predict treatment response or outcome in melanoma patients. We hypothesized that methylation of tumor-related genes detected in serum DNA could predict disease outcome and therapeutic response in patients receiving concurrent biochemotherapy (BC) for metastatic melanoma. Patients and Methods American Joint Committee on Cancer stage IV melanoma patients (N = 50) had blood drawn before administration of BC. Patients (n = 47) were classified as BC responders or nonresponders. Responders (n = 23) demonstrated a complete or partial response following BC; nonresponders (n = 24) demonstrated progressive disease. Hypermethylation of Ras association domain family 1 (RASSF1A), retinoic acid receptor-beta 2 (RAR-beta 2), and O-6-methylguanine DNA methyltransferase (MGMT) genes were assessed by methylationspecific polymerase chain reaction. Results Circulating methylated RASSF1 was significantly less frequent for responders (three of 23 patients; 13%) than nonresponders (10 of 24 patients; 42%, P = 028). Patients with RASSF1, RAR-beta 2, or at least one serum methylated gene had significantly worse overall survival than patients with no methylated genes (log-rank, P = .13, .021, and 01, respectively). Methylated RASSF1 was the only factor that significantly correlated with overall survival and BC response (risk ratio, 2.38; 95% Cl, 1.16 to 4.86; P = 018; odds ratio 0.21; 95% Cl, 0.05 to 0.90; P = 036). Conclusion Detection of circulating methylated DNA in serum can predict response to BC and disease outcome.