Integrated imaging cytology profiling system for rapid point-of-care molecular diagnosis of leptomeningeal metastasis in breast cancer.

3073 Background: Leptomeningeal metastasis (LM) from breast cancer has a poor prognosis (median survival ~4 months). Early and accurate diagnosis and phenotyping enable timely therapeutic intervention, particularly with emerging targeted agents such as antibody–drug conjugates (ADCs), to improve clinical outcomes. Yet, MRI and CSF cytology often lack sensitivity. We developed iSCOPE, an integrated imaging cytology platform that rapidly enriches and detects tumor cells in CSF via single-cell immunomolecular profiling. Methods: Breast cancer patients with neurological symptoms and/or suspicion for LM were enrolled in the study (IRB: KNUCH 2020-08-015). CSF (5–10 mL) was obtained by lumbar puncture for iSCOPE testing, and the rest was for conventional cytology examination. iSCOPE (integrated single-cell on-chip point-of-care evaluation) enriches large epithelial cells from unprocessed CSF at single-cell capture sites in a microfluidic chip while smaller blood cells pass through. Captured cells are then immunolabeled with QUAD markers (a four-marker combination overexpressed in breast cancer), as well as HER2 and ER/PR, for phenotyping. Automatic quantitative fluorescence imaging using a miniaturized imager reports the total cells, QUAD-positive cells, and their phenotypes in 1 hour. iSCOPE was validated using FNA cytology samples and then applied to CSF samples. Results were compared with conventional CSF cytology. Results: In the validation study using FNA cytology samples, iSCOPE demonstrated excellent breast cancer detection accuracy based on QUAD-positive cell counts (area under the curve/AUC = 0.995), and receptor phenotyping showed concordance with clinical pathology (AUC > 0.9). In CSF testing, iSCOPE correctly discriminated between LM ( n = 7) and control CSF samples from patients with normal pressure hydrocephalus ( n = 5). In serially collected CSF testing due to inconclusive diagnoses, iSCOPE detected LM in two cases, a few months earlier than conventional cytology when a suspicious finding was initially made (Table 1). Conclusions: This study demonstrates the clinical feasibility of iSCOPE for CSF-based diagnosis of LM in breast cancer. iSCOPE addresses current challenges in cytology analysis by incorporating a microfluidic chip to enrich for scant, suspicious cells and by using immunomolecular profiling to detect tumor cells. The CSF study results highlight the potential clinical use of iSCOPE for detecting LM in a point-of-care setting. CSF analysis for LM diagnosis. ID Primary subtype LM diagnosis (MRI) LM diagnosis (Cytology) LM diagnosis (iSCOPE) S1 TNBC 2/8/2025 2/10/2025 2/10/2025 S2 HR+ HER2- Negative 2/18/2025 Suspicious S3 HR+ HER2- 4/2/2025 3/31/2025 8/14/2024 S4 HR+ HER2- 2/28/2025 (suspicious) 8/28/2025 2/17/2025 S5 TNBC 12/26/2025(suspicious) Negative Negative