C. Hall1, M. Ross1, M. Karhade1, J. B. Bauldry1, J. Upshaw1, R. Royal1, L. Valad1, A. Lucci1 1University Of Texas MD Anderson Cancer Center,Department Of Surgical Oncology,Houston, TX, USA
Introduction: Our group (and others) have demonstrated that circulating melanoma cells (CMCs) can be detected in stage IV melanoma patients, yet there is limited data regarding the prognostic significance of CMCs. The aim of this study was to determine if CMCs detected with a semi-automated platform predict early relapse in stage IV melanoma patients.
Methods: Serial CMC assessments (7.5mL blood) were performed in patients with stage IV cutaneous melanoma (n=58) using the CellSearch® system (Janssen Diagnostics). CD146+ cells were immunomagnetically enriched; CD146+, HMW-MAA+/, CD45-/, and CD34- nucleated cells were considered CMCs. We correlated the identification of CMCs with tumor characteristics using chi-square or Fisher exact tests. Log-rank test and Cox regression analysis was applied to determine the association of circulating tumor cells with relapse-free survival. Relapse-free survival (RFS) was compared between patients with ≥1 CMC detected at baseline (first blood draw) or at second blood draw (6 months after baseline) versus those with no CMCs at baseline and at the second blood draw.
Results: CMCs were identified in 28 of 58 (48%) patients at either baseline or at second blood draw. We observed no significant association between CMC presence at baseline draw and primary tumor factors such as presenting Breslow thickness, number of mitotic figures, or ulceration (P=NS for all factors). Relapse occurred in 22 of 28 (79%) stage IV patients with ≥1 CMC versus 12 of 30 (40%) with no CMCs at baseline and at second draw (log-rank P =0.02, HR 2.24, 95% CI 1.10 to 4.55; P=0.02). No other primary tumor characteristic, including presenting Breslow thickness, number of mitotic figures, ulceration, or Braf status, predicted shortened relapse-free survival.
Conclusion: Using a semi-automated platform, CMCs detected at baseline or at a subsequent blood draw, predicted relapse in stage IV melanoma patients. These data strongly support further study with long follow-up and serial blood draw to validate the prognostic significance and utility of CMC measurement in melanoma patients.
