Imaging Mass Cytometry (IMC) as a Tool to Characterize Circulating Tumor Cells (CTCs) in Preclinical Mouse Models

Abstract Circulating tumor cells (CTCs), particularly multicellular clusters, are associated with poor prognosis and may provide insight into mechanisms of metastasis and therapy resistance. Unbiased approaches for functionally characterizing CTCs in liquid biopsies are therefore urgently needed. Here, we evaluate multiplex imaging mass cytometry (IMC) for CTC analysis in mice bearing human xenograft tumors. In a single-step workflow, IMC uses metal-conjugated antibodies to simultaneously detect numerous proteins and post-translational modifications in minimally processed, small-volume blood samples collected from the tail vein or heart. Using breast cancer cell lines and a patient-derived xenograft (PDX), we assessed a panel of antibodies, including human-specific markers such as Lamin B1 (LMNB1), to enable cross-species interpretation. Combined with manual review, HALO AI–based cell segmentation was used to identify CTCs and quantify marker expression. This approach enables studies of how genetic and pharmacologic interventions alter the properties of single CTCs and CTC clusters in tumor-bearing mice. Competing Interest Statement The authors have declared no competing interest. Footnotes ↵♦ CCR Mass Cytometry Core, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA Competing Interests: The authors do not declare competing interests. Data on Lamin B1 have been added.