Clonal heterogeneity of melanoma in a paradigmatic case study: Future prospects for circulating melanoma cells

Maria Chiara Scaini, Jacopo Pigozzo, Marco Pizzi, Mariangela Manicone, Vanna Chiarion-Sileni, Pamela Zambenedetti, Massimo Rugge, Paola Zanovello, Elisabetta Rossi, Rita Zamarchi, Antonella Facchinetti

Research output: Contribution to journalArticle

Abstract

The management of metastatic melanoma is a difficult matter. Nevertheless, the advent of target therapy has significantly improved patient outcome, provided that tumor molecular characteristics become available: the detection of drug-resistant clones can contribute to understanding the reasons for resistance onset, influencing the choice of subsequent therapy. This work aimed to provide a possible explanation for the early resistance to vemurafenib developed by a patient with melanoma, and concurrently to assess the extent, and role, of the tumor clonal heterogeneity. We analyzed tissue samples from different sites and time points: first/second primary, three lymph node metastases, and circulating melanoma cells (CMCs). We first investigated these samples by the routine Sanger sequencing for BRAF, NRAS, and KIT, and then, we focused on specific hotspots by droplet digital PCR. We detected a BRAF V600E mutation by Sanger sequencing in the second primary and distant lymph node metastases, but not in the first primary or sentinel lymph node. Interestingly, by droplet digital PCR, the V600E mutation was also detected in the first primary, and the V600K in the second primary and metastases. Moreover, we identified a rare KIT V569G mutation, appearing to be CMC exclusive. This finding confirms the potential of CMCs as a source of tumor material for genetic analysis, reflecting real-time systemic disease evolution and, most likely, the most aggressive, treatment-resistant clones. In summary, this work underlines the importance of CMCs in the early identification of tumor clones putatively responsible for therapy resistance.

Original languageEnglish
Pages (from-to)89-94
Number of pages6
JournalMelanoma Research
Volume29
Issue number1
DOIs
Publication statusPublished - Feb 1 2019

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Keywords

  • circulating melanoma cells
  • droplet digital PCR
  • laser capture microdissection
  • melanoma clonal heterogeneity
  • Sanger sequencing
  • target therapy

ASJC Scopus subject areas

  • Oncology
  • Dermatology
  • Cancer Research

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