Detection and quantification of CSF malignant cells by the CellSearch® technology in patients with melanoma leptomeningeal metastasis

Abstract

Melanoma is the most frequent solid tumor associated with leptomeningeal metastasis (LM). The usual diagnostic tools, that is, cytomorphological assessment of cerebro-spinal fluid (CSF) and gadolinium-enhanced MRI of the entire neuraxis both lack effectiveness. The CellSearch Veridex technology for the detection of circulating tumor cells (CTC) in blood was designed for the follow-up and prognosis of breast, prostate, colorectal, and lung cancer, which express EpCAM markers. We have previously adapted this technology to detect malignant cells in the CSF of breast cancer LM. Our objective here was to check if this technology would also allow the detection and the enumeration of CTC in the CSF of melanoma patients presenting with LM although melanoma does not express EpCAM markers. On the occasion of the intrathecal treatment of LM in 2 melanoma patients, 5 mL of CSF and 7.5 mL of blood were collected on CellSave Preservative Tubes and analyzed within 3 days after CSF sampling using a melanoma-dedicated kit. The CellSearch Veridex technology was then adapted to direct enrichment, enumeration, and visualization of melanoma cells in the CSF. CD146+, HMW-MAA+, CD34-, and CD45- cells with typical morphology could be observed and enumerated sequentially with reproducible results, corresponding to CSF melanoma cells (CSFMC). In contrast to the current gold standard cytomorphological analysis, this new approach allowed a precise quantification of CSFMC in all samples concomitantly analyzed. This methodology, established on a limited volume of sample and allowing delayed processing, could prove of great interest in the diagnosis and follow-up of melanoma patients with LM.

Case Report: Detection and quantification of tumor cells in peripheral blood and ascitic fluid from a metastatic esophageal cancer patient using the CellSearch® technology

“…We have recently documented a new method to identify and quantify malignant cells in the CSF using the CellSearch ® technology 7, 8 , suggesting its potential usefulness for follow-ups and treatment evaluations with cancer patients. As described here, this new method makes it also possible to detect and quantify the presence of tumor cells, either isolated or associated as microclusters in ascitic fluid, which in some studies are recognized as a “signature” of malignant metastases 18, 19 .…”

“…The blood sample was processed in the CellTracks AutoPrep system by using the CTC kit and analyzed with the CellTracks Analyzer. For analysis of the ascitic sample, we used the method developed for the detection of tumor cells in cerebrospinal fluid samples (CSF) 7, 8 . This methodology revealed the presence of 47 CTCs (EpCAM + , CK + , and CD45 - ) in the 7.5 ml blood sample, some with morphologically apoptotic features, and over 13,000 CTCs (EpCAM + , CK + , and CD45 - ) in the 5 ml ascitic sample.…”

Pathways and therapeutic targets in melanoma

“…Nevertheless, use of the CellSearch platform was reported to detect CTCs in 40% of patients with advanced melanoma, and the number of CTCs was prognostic itself for overall survival and reflective of treatment outcomes [333]. The CellSearch Veridex platform was recently adapted for melanoma markers, and was reported to be successful in detection and quantification of CTCs in cerebrospinal fluid in two melanoma patients with leptomeningial metastases [334]…”

Improving the CellSearch® system

“…The melanoma cells are identified as nucleated cells that express the high-molecular-weight melanoma-associated antigen and lack CD45 and CD34 [22]. Circulating melanoma cells identified in this manner also associate with poor clinical outcome [21,22,[41][42][43].…”