Rare cell capture technology for the diagnosis of leptomeningeal metastasis in solid tumors

Objective: To evaluate the utility of rare cell capture technology (RCCT) in the diagnosis of leptomeningeal metastasis (LM) from solid tumors through identification of circulating tumor cells (CTCs) in the CSF. Methods: In this pilot study, CSF samples from 60 patients were analyzed. The main patient cohort consisted of 51 patients with solid tumors undergoing lumbar puncture for clinical suspicion of LM. Those patients underwent initial MRI evaluation and had CSF analyzed through conventional cytology and for the presence of CTCs using RCCT, based on immunomagnetic platform enrichment utilizing anti-epithelial cell adhesion molecule antibody-covered magnetic nanoparticles. An additional 9 patients with CSF pleocytosis but without solid tumors were separately analyzed to ensure accurate differentiation between CTCs and leukocytes. Results: Among the 51 patients with solid tumors, 15 patients fulfilled criteria for LM. CSF CTCs were found in 16 patients (median 20.7 CTCs/mL, range 0.13 to >150), achieving a sensitivity of 100% as compared with 66.7% for conventional cytology and 73.3% for MRI. One patient had a false-positive CSF CTC result (specificity = 97.2%); however, that patient eventually met LM criteria 6 months after the tap. CSF CTCs were not found in any of the additional 9 patients with CSF pleocytosis. Conclusion: RCCT is an accurate, novel method for the detection of LM in solid tumors, potentially providing earlier diagnostic confirmation and sparing patients from repeat lumbar punctures.