Glycan Markers as Potential Immunological Targets in Circulating Tumor Cells

We present here an experimental approach for exploring a new class of tumor biomarkers that are overexpressed by circulating tumor cells (CTCs) and are likely targetable in immunotherapy against tumor metastasis. Using carbohydrate microarrays, anti-tumor monoclonal antibodies (mAbs) were scanned against a large panel of carbohydrate antigens to identify potential tumor glycan markers. Subsequently, flow cytometry and fiber-optic array scanning technology (FAST) were applied to determine whether the identified targets are tumor-specific cell-surface markers and are, therefore, likely suitable for targeted immunotherapy. Finally, the tumor glycan-specific antibodies identified were validated using cancer patients' blood samples for their performance in CTC-detection and immunotyping analysis. In this article, identifying breast CTC-specific glycan markers and targeting mAbs serve as examples to illustrate this tumor biomarker discovery strategy.