Isolation of Circulating Tumor Cells to Diagnose Melanoma and Evaluate the Efficacy of Surgical Resection Using Melanoma‐Specific Microsystem

Abstract

Melanoma is one of the most aggressive skin cancers due to its potential to metastasize widely in the body. The risk of metastasis is increased with later detection and increased thickness of the primary lesion, thus early identification/surgical removal is critical for higher survival rates. Recent advances in liquid biopsy have proposed less‐invasive alternatives for cancer diagnosis and monitoring using minimal invasion at sample collection, and circulating tumor cells (CTCs) have been considered a promising blood‐based surrogate marker of primary tumors. Herein, the melanoma‐specific OncoBean platform (MelanoBean) conjugated with melanoma specific antibodies is used. From the comprehensive studies based on change in the number and characteristics of CTCs/CTCs‐clusters pre‐ and post‐surgical treatment, this work demonstrates that melanoma patients (n = 45) at all stages (I–IV) have a noticeable number of CTCs as well as CTC‐clusters compared to healthy donors (n = 9) (p = 0.0011), and surgical treatment leads to a significant decrease in the CTC number (p < 0.0001). The CTCs recovered from the device undergo molecular profiling for melanoma‐associated genes expression using multiplexed qRT‐PCR, demonstrating the ability to monitor molecular signature through treatment. The presented MelanoBean and the comprehensive approach will empower prognostic value of CTCs in melanoma in much larger cohort studies.

The role of micrometastasis in high‐risk skin cancers

“…2 The recent recognition of early blood borne seeding and of the key role of lymphatic processing for cancer cells has forced a major revision of metastatic progression models. 12,[29][30][31][32][33][34][35][36] Significant evidence is emerging to suggest a high correlation between early circulating cancer cells and poor survival outcomes for solid cancers, including melanoma, 32,33 MCC 12,34,35 and SCC. 13 The recognition that solid cancers seed micrometastases from their inception supports the view that cancer is a systemic disease and overturns the purely mechanistic concept of sequential carcinogenesis.…”

“…This includes CTCs and cell-free circulating nucleic acids (DNA, mRNA, micro-RNA, and long non-coding RNA), serum proteins, 'tumour-educated platelets', and exosomes. 2,4,5 CTCs are detected very early in the course of multiple cancers, including melanoma, 32,33,60 MCC, 4,12,34,36 and recently for SCC. 13,14 CTCs typically have a short half-life in the circulation.…”

“…The metastatic cascade is the term used to describe the process in which cancer cells, singly or as micrometastases disengage from the primary tumour, invade proximate blood or lymph vessels and eventually form overt macro‐metastatic disease 2 . The recent recognition of early blood borne seeding and of the key role of lymphatic processing for cancer cells has forced a major revision of metastatic progression models 12,29–36 . Significant evidence is emerging to suggest a high correlation between early circulating cancer cells and poor survival outcomes for solid cancers, including melanoma, 32,33 MCC 12,34,35 and SCC 13 .…”

“…CTCs are detected very early in the course of multiple cancers, including melanoma, 32,33,60 MCC, 4,12,34,36 and recently for SCC 13,14 . CTCs typically have a short half‐life in the circulation.…”

Orthotopic model for the analysis of melanoma circulating tumor cells

“…Moreover, the number of CTCs reflects patients' responses to BRAF/MEK inhibitor treatment 7 . Recently, a specific microfluidic device for capturing melanoma CTCs was introduced 8 . However, both the understanding and the analysis of CTCs are limited due to challenges associated with the low abundance of CTCs, their phenotypic heterogeneity, the lack of reliable and reproducible detection and isolation techniques, and last but not least, the lack of suitable animal models for studies of melanoma-derived CTCs 9 .…”