Microphthalmia transcription factor as a molecular marker for circulating tumor cell detection in blood of melanoma patients.

PURPOSE: Microphthalmia transcription factor (Mitf), which is important in melanocyte development and melanoma growth, was assessed using real-time quantitative reverse transcription-PCR assay to investigate its expression as a marker for circulating melanoma cells in blood and determine the correlation with disease stage and survival in melanoma patients. EXPERIMENTAL DESIGN: In optimization studies for Mitf, we tested 15 melanoma cell lines, 41 peripheral blood lymphocytes from healthy volunteers, and 21 metastatic melanoma tissues. Blood specimens were procured from 90 patients with stage I (n = 20), stage II (n = 20), stage III (n = 28), and stage IV (n = 22) melanoma. Blood specimens were also obtained at four bleed intervals from 58 patients enrolled in a prospective multicenter trial of biochemotherapy before and after surgical treatment of American Joint Committee on Cancer stage III melanoma. RESULTS: Under the optimized conditions, Mitf was negative in healthy peripheral blood lymphocytes and positive in all melanoma cell lines and 18 (86%) melanoma tissues. In the 90 patients, the rate of Mitf detection was higher with increasing American Joint Committee on Cancer stage (P < 0.0001). In the 58 patients treated with biochemotherapy and surgery, Mitf detection decreased with treatment (P = 0.019). Mitf detection after treatment was associated with a significantly lower relapse-free (P < 0.0001) and overall (P = 0.001) survival and was a significant independent prognostic factor for relapse-free (risk ratio, 5.63; P = 0.0004) and overall (risk ratio, 5.36; P = 0.005) survival. CONCLUSIONS: Mitf detection in blood can indicate subclinical metastatic disease and predict treatment outcome in melanoma patients.

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-beta2 (RAR-beta2), and O6-methylguanine DNA methyltransferase (MGMT) genes were assessed by methylation-specific polymerase chain reaction. RESULTS: Circulating methylated RASSF1A was significantly less frequent for responders (three of 23 patients; 13%) than nonresponders (10 of 24 patients; 42%; P = .028). Patients with RASSF1A, RAR-beta2, or at least one serum methylated gene had significantly worse overall survival than patients with no methylated genes (log-rank, P = .013, .021, and .01, respectively). Methylated RASSF1A was the only factor that significantly correlated with overall survival and BC response (risk ratio, 2.38; 95% CI, 1.16 to 4.86; P = .018; odds ratio = 0.21; 95% CI, 0.05 to 0.90; P = .036). CONCLUSION: Detection of circulating methylated DNA in serum can predict response to BC and disease outcome.

Impact of gene polymorphisms on clinical outcome for stage IV melanoma patients treated with biochemotherapy: an exploratory study.

PURPOSE: Biochemotherapy can achieve high response rates in advanced melanoma, but the factors that influence regression and survival remain unknown. The present exploratory study tested the hypothesis that cytokine gene polymorphisms predict clinical outcome in stage IV melanoma patients treated with biochemotherapy. EXPERIMENTAL DESIGN: Ninety patients with stage IV melanoma were treated with biochemotherapy, including cisplatin, vinblastine, and dacarbazine combined with interleukin (IL)-2 and IFN-alpha either with or without tamoxifen. Cytokine gene polymorphisms for IFN-gamma (+874A-->T) and IL-10 (-1082G-->A) were assessed. X-ray repair cross-complementing gene 1 (XRCC1; Arg399Gln), xeroderma pigmentosum complementary group D (XPD; Lys751Gln), and excision repair cross-complementing gene 1 (ERCC1; codon 118) DNA repair polymorphisms were also determined. RESULTS: IFN-gamma (+874A-->T) gene polymorphism was statistically significantly associated with response (P = 0.001), progression-free survival (P = 0.0012), and overall survival (P < 0.001), whereas the IL-10 polymorphism was marginally associated with response (P = 0.03) and overall survival (P = 0.065). Multivariate analysis revealed that IFN-gamma (+874A-->T) independently predicted overall survival (P = 0.003). The ERCC1 polymorphism was weakly associated with overall survival (P = 0.045). Combining polymorphisms for IFN-gamma, IL-10, and ERCC1 stratified patients into four distinct groups with significantly different clinical outcome (P < 0.001), so that patients with more "favorable" polymorphisms had a better outcome. CONCLUSIONS: Cytokine gene polymorphisms predicted clinical outcome for advanced melanoma patients who received biochemotherapy. The combined effects of multiple genetic polymorphisms may provide more accurate prognostic information. Additional independent studies are needed to confirm these pilot findings.