Melanoma inhibitory activity: a novel serum marker for uveal melanoma.

The aim of this study was to evaluate the tumour-associated antigen melanoma inhibitory activity (MIA) as a potential novel serological tumour marker in primary and metastatic uveal melanoma in both the laboratory and the clinical setting. In the laboratory setting, immunohistochemical staining with MIA antibody was performed in paraffin-embedded tissues from six amelanotic uveal melanomas and eight metastatic lesions of uveal melanomas. In the clinical setting, serum samples of 139 patients with uveal melanoma were examined; eight of these patients had overt metastatic disease. Sixty-one initially metastatic disease-free patients were followed over time (median follow-up 240 days, 95% confidence interval 60-883 days) and MIA levels were assessed repeatedly. A one-step enzyme-linked immunosorbent assay was used to quantify the MIA serum levels. In the laboratory setting, five of the six primary uveal melanomas and seven of the eight metastatic lesions stained immunohistologically positive for MIA. In the clinical setting, the 131 patients without overt metastatic disease demonstrated a median serum concentration of MIA of 6.6 ng/ml. In the eight patients with overt metastatic disease, the median serum concentration of MIA was 26.28 ng/ml. This difference was highly statistically significant (P < 0.001, analysis of variance). During follow-up, three initially metastatic disease-free patients developed overt metastatic disease, and the MIA level increased from a median of 6.6 ng/ml before to 29.2 ng/ml after clinical detection of metastatic disease. In the 58 other patients, the serum level remained stable during the entire follow-up period. In conclusion, MIA is expressed in primary and metastatic lesions of uveal melanomas, and a statistically significant elevation in MIA serum levels in patients who develop metastatic disease due to uveal melanoma indicates its promising role as a serum marker for monitoring uveal melanoma patients for metastasis.

Molecular and prognostic classification of advanced melanoma: a multi-marker microcontamination assay of peripheral blood stem cells.

The presence or absence of melanoma cells in human peripheral blood has recently been shown to be associated with disease prognosis, including overall survival. The detection of tyrosinase mRNA-positive circulating melanoma cells by reverse transcription-polymerase chain reaction (RT-PCR) has been limited to disseminated tumours expressing measurable amounts of this melanocyte-specific enzyme. To biologically classify both melanotic and amelanotic melanomas and to evaluate the clinical and prognostic relevance of tumour cell microcontamination, we examined autologous peripheral blood stem cell (PBSC) harvests from patients with advanced malignant melanoma prior to dose-escalated chemotherapy. To assay heterogeneous melanoma cell antigen expression, we developed a highly sensitive RT-PCR using four melanoma- and one tumour-associated antigen as molecular markers. Expression of the melanocyte-associated transcripts of tyrosinase, MART1/Melan-A, tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2) as well as the tumour-specific transcript of MAGE-3 was analysed by RT-PCR in PBSC harvests from 31 patients. Seven of the 31 PBSC harvests tested positive for one or more molecular markers: two patients for tyrosinase only, and one patient for MAGE-3 only, one patient for tyrosinase and MAGE-3, one for tyrosinase and MART1/Melan-A, and two patients for tyrosinase, MART1/Melan-A, TRP-2 and MAGE-3. mRNA-positive patients exhibited a significantly impaired overall survival (P = 0.0032), with a median survival of 3 months as opposed to 10 months in PBSC mRNA-negative patients. In conclusion, the use of this multiple-marker microcontamination assay allowed for molecular and prognostic classification of advanced malignant melanoma.