Malignant Melanoma: Landscape of Molecular Markers

<b>Background:</b> In melanoma diagnostics key molecular markers, such as <i>BRAF</i>, <i>NRAS</i>, and <i>KIT</i> mutations also paved the way for targeted therapies. Immunotherapies, including immune checkpoint inhibitors like anti-CTLA-4 and anti-PD-1/PD-L1, have revolutionized treatment, improving survival outcomes for advanced-stage melanoma patients. Despite these advances, challenges such as resistance to targeted therapies and variability in patient responses to immunotherapy remain critical issues. The purpose of the project is to characterize the molecular landscape of a set of 28 malignant melanomas using next-generation sequencing, identify the prevalence and nature of class 3-5 variants (e.g., <i>NRAS</i>, <i>BRAF</i>, <i>KIT</i>, <i>TP53</i>), assess the genetic complexity and molecular patterns, and use these insights to inform personalized therapies and optimize patient stratification for potential combination strategies (targeted therapy followed by immunotherapy). <b>Methods:</b> We analyzed a set of malignant melanoma of the skin of 17 women (61%) and 11 men (39%) at the age of 23 to 85 years (median: 63 years) by tumor-only next generation sequencing. <b>Results:</b> 22/28 cases (79%) present a pathogenic or likely pathogenic variant with an allelic frequency of ≥5%. In total 42 distinct somatic pathogenic or likely pathogenic variants with an allelic frequency of ≥5% could be detected. The most frequent pathogenic molecular alteration in these melanomas were found in <i>NRAS</i> (25%) and <i>BRAF</i> (25%). The most frequent molecular alteration of unknown significance was found in <i>FANDC2</i> (46%), <i>NOTCH3</i> (39%), <i>ARID1A</i> (32%), <i>PMS2</i> (32%), <i>POLE</i> (29%), <i>NOTCH1</i> (29%), <i>TSC2</i> (25%), <i>SMARCA4</i> (25%), <i>ATR</i> (25%) and <i>TERT</i> (21%). <b>Conclusions:</b> While <i>NRAS</i> and <i>BRAF</i> were the most frequent actionable alterations (each 25%), a broad spectrum of variants of unknown significance (e.g., <i>FANDC2</i>, <i>NOTCH3</i>, <i>ARID1A</i>, <i>PMS2</i>, <i>POLE</i>, <i>NOTCH1</i>, <i>TSC2</i>, <i>SMARCA4</i>, <i>ATR</i> and <i>TERT</i>) also predominates, underscoring the genetic complexity of melanoma. These variants complicate clinical decision-making because their contribution to tumorigenesis, therapeutic response, and prognosis remains uncertain. Nevertheless, these variants also offer a valuable resource for future research, as they may uncover novel pathogenic mechanisms or therapeutic targets once their significance is elucidated. Integrating comprehensive genetic profiling with immunologic markers can enhance patient stratification and support rational, potentially synergistic strategies, such as combining targeted therapies with immunotherapy, to optimize clinical outcomes. This study is limited due to a small cohort and limited available clinical data. Larger cohort studies and prospective clinical trials are necessary to validate and explore the interplay between molecular and immune biomarkers as well as general biological mechanism in paving therapeutic way in melanoma.