title: Prevalence and heterogeneity of circulating tumour cells in metastatic cutaneous melanoma.
abstract: We previously demonstrated that circulating tumour cells (CTCs) are detectable by the MelCAM and high molecular weight melanoma-associated antigen (HMW-MAA)-dependent CellSearch platform. However, CTCs which do not express these capture and detection markers are not detectable by CellSearch. Consequently, we explored the use of isolation by size of epithelial tumour cells (ISET), a marker independent, filtration-based device to determine the prevalence and heterogeneity of CTCs in metastatic cutaneous melanoma patients. Ninety patients were prospectively recruited and blood samples taken before treatment. Patients' blood was filtered using the ISET platform. CTCs were enumerated using dual immunohistochemistry with positive selection by S100 expression and exclusion of leucocytes and endothelial cells expressing CD45 or CD144, respectively. A panel of markers (Melan-A, MITF, MelCAM, high molecular melanoma-associated antigen, CD271 and MAGEC) was also examined. Fifty-one patients (57%) had CTCs (range 1-44 CTCs/4 ml blood) and 12 patients also had circulating tumour microemboli. Seven patients had S100- CTCs, 11 patients' CTCs were S100+ and 33 patients had S100+ and S100- CTCs. Substantial intrapatient and interpatient heterogeneity was observed for all other melanoma-associated markers. CTCs in metastatic cutaneous melanoma are detectable using the flexible marker-independent ISET platform. CTCs display significant marker expression heterogeneity implying that marker-dependent platforms would not detect all CTCs and multimarker assays are now required to reveal the biological significance of this CTC heterogeneity.
authors.affiliation: aClinical and Experimental Pharmacology Group, Paterson Institute for Cancer Research bThe Christie NHS Foundation Trust cSchool of Cancer and Enabling Sciences, Manchester Cancer Research Centre and Manchester Academic Health Sciences Centre, University of Manchester, Manchester dAstraZeneca Pharmaceuticals, Alderley Park, UK.
authors.forename: Leila
authors.initials: L
authors.lastname: Khoja
authors.forename: Patrick
authors.initials: P
authors.lastname: Shenjere
authors.forename: Clare
authors.initials: C
authors.lastname: Hodgson
authors.forename: Jackie
authors.initials: J
authors.lastname: Hodgetts
authors.forename: Glen
authors.initials: G
authors.lastname: Clack
authors.forename: Andrew
authors.initials: A
authors.lastname: Hughes
authors.forename: Paul
authors.initials: P
authors.lastname: Lorigan
authors.forename: Caroline
authors.initials: C
authors.lastname: Dive
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D005260:Female; D018740:Genetic Heterogeneity; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D008545:Melanoma / Q000097:blood / Q000235:genetics / Q000473:pathology*; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D015995:Prevalence; D012878:Skin Neoplasms / Q000097:blood / Q000235:genetics / Q000473:pathology*; D000096142:Cutaneous Malignant Melanoma
chemical_list: D014408:Biomarkers, Tumor