Liquid biopsy for diagnostic and prognostic evaluation of melanoma

Abstract

Melanoma is the most aggressive form of skin cancer, and the majority of cases are associated with chronic or intermittent sun exposure. The incidence of melanoma has grown exponentially over the last 50 years, especially in populations of fairer skin, at lower altitudes and in geriatric populations. The gold standard for diagnosis of melanoma is performing an excisional biopsy with full resection or an incisional tissue biopsy. However, due to their invasiveness, conventional biopsy techniques are not suitable for continuous disease monitoring. Utilization of liquid biopsy techniques represent substantial promise in early detection of melanoma. Through this procedure, tumor-specific components shed into circulation can be analyzed for not only diagnosis but also treatment selection and risk assessment. Additionally, liquid biopsy is significantly less invasive than tissue biopsy and offers a novel way to monitor the treatment response and disease relapse, predicting metastasis.

Keywords: circulating biomarkers; diagnosis; liquid biopsy; melanoma; prognosis.

FIGURE 1

Circulating biomarkers in melanoma. CTC, circulating tumor cell; miRNA, microRNA; ctDNA, circulating tumor DNA.

FIGURE 2

Potential clinical applications of circulating biomarkers in the treatment of melanoma. (A) Schematic time course of disease management and tumor size in melanoma patients undergoing chemotherapy (or immunotherapy) and surgery. Circulating tumor DNA (ctDNA) analysis allows early detection, monitoring treatment response, monitoring recurrence, and predicting metastasis. Circulating tumor cells (CTCs) analysis can assist the selection of immune checkpoint inhibitor. miRNAs and protein biomarkers analysis can provide complementary information and help in melanoma diagnosis and treatment. (B) Use of miRNAs in combination with ctDNA and CTCs allows higher disease detection. A spike in ctDNA level reflects transient tumor cell death by systemic therapy.