Pair-matched analysis of Circulating Melanoma Cells (CMCs) before and after Immunotherapy in Relation to other Melanoma-Specific Biomarkers

Melanoma remains challenging in terms of diagnosis and treatment, and there is an urgent need to implement accurate diagnostic methods and personalized treatment to improve clinical outcomes. Therefore, it may be useful to enrich the panel of melanoma markers already in use and develop combinations of biomarkers for disease prognosis and monitoring. Data suggest that a promising biomarker for such a combination is circulating melanoma cells (CMCs). Although the relevances of various biomarkers in diagnosis, prognosis and treatment monitoring in melanoma have been extensively studied, we aimed at comprehensive investigation and comparison of liquid biopsy and tissue biomarkers with clinical status of the patient. Specifically, we focused on CMCs, by comparing the number of CMCs, including pre- and post-treatment. Furthermore, we have assessed the expression of the PMEL and Melan-A markers and the S100B and TIMP-1 protein levels in representative blood samples from melanoma patients and healthy controls. The number of CMCs in the study group was significantly higher than in the CMC-negative control group. However, there was no significant difference between the incidence of CMCs in the pre- and post-treatment blood draws. Nonetheless, we have observed a negative correlation between LDH levels and PFS, and a negative correlation between S100B levels and lymphocyte counts. The results of the study indicate that combinations of biomarkers, rather than any single biomarker alone, possess the highest clinical application potential, which urges further research on larger patient groups.