Circulating tumor cells (CTCs) are an important biomarker for cancer prognosis and treatment monitoring. However, the heterogeneity of the physical and biological properties of CTCs limits the efficiency of various approaches used to isolate small numbers of CTCs from billions of normal blood cells. To address this challenge, we developed a lateral filter array microfluidic (LFAM) device to integrate size‐based separation with immunoaffinity‐based CTC isolation. The LFAM device consists of a serpentine main channel, through which most of a sample passes, and an array of lateral filters for CTC isolation. The unique device design produces a two‐dimensional flow, which reduces nonspecific, geometric capture of normal cells as typically observed in vertical filters. The LFAM device was further functionalized by immobilizing antibodies that are specific to the target cells. The resulting devices captured pancreatic cancer cells spiked in blood samples with (98.7±1.2) % efficiency and were used to isolate CTCs from patients with metastatic colorectal cancer.

Isolation and analysis of cancer cells from body fluids have significant implications in diagnosis and therapeutic treatment of cancers. Circulating tumor cells (CTCs) are cancer cells circulating in the peripheral blood or spreading iatrogenically into blood vessels, which is an early step in the cascade of events leading to cancer metastasis. Therefore, CTCs can be used for diagnosing for therapeutic treatment, prognosing a given anticancer intervention, and estimating the risk of metastatic relapse. However, isolation of CTCs is a significant technological challenge due to their rarity and low recovery rate using traditional purification techniques. Recently microfluidic devices represent a promising platform for isolating cancer cells with high efficiency in processing complex cellular fluids, with simplicity, sensitivity, and throughput. This review summarizes recent methods of CTC isolation and analysis, as well as their applications in clinical studies.

Background: Pancreatic ductal adenocarcinoma (PDAC) requires multimodal therapeutic approaches and disease monitoring for effective treatment. Liquid biopsy biomarkers, including circulating tumor cells (CTCs) and cancer stem-like cells (CSCs), hold promise for evaluating treatment response promptly and guiding therapeutic modifications. Methods: From 24 patients with metastatic PDAC (stage IV, M1) undergoing active systemic treatment, we collected 78 blood samples at different time points for CTC and CSC isolation using a microfluidic platform functionalized with antibodies against a CTC biomarker, epithelial cell adhesion molecule (EpCAM), or a CSC biomarker, CD133. These isolated cells were further verified, via fluorescent staining and imaging, using cytokeratin (CK), CD45, and nucleic acid stain 4',6-diamidino-2-phenylindole (DAPI). Results: The majority (84.4%) of patient blood samples were positive for CTCs (EpCAM + CK + CD45 - DAPI + ) and 70.8% of patient blood samples were positive for CSCs (CD133 + CK + CD45 - DAPI + ), using the highest baseline value of healthy samples as threshold. The CTC subtypes (EpCAM + CK + CD45 - DAPI + CD133 + and EpCAM + CK + CD45 - DAPI + CD133 - ) and CSC subtypes (CD133 + CK + CD45 - DAPI + EpCAM + and CD133 + CK + CD45 - DAPI + EpCAM - ) were also analyzed using immunochemical methods. In several cases, CSCs exhibited cytokeratin expression that did not express EpCAM, indicating that they will not be detected using EpCAM-based isolation. Conclusion: The microfluidic platform enabled the reliable isolation of CTCs and CSCs from PDAC patient samples, as well as their subtypes. Complementary assessment of both CTCs and CSCs appears advantageous to assess the profile of tumor progressing in some cases. This research has important implications for the application and interpretation of approved methods to detect CTCs.

Circulating tumor cells (CTCs) are an important biomarker for cancer prognosis and treatment monitoring. However,t he heterogeneity of the physical and biological properties of CTCs limits the efficiency of various approaches used to isolate small numbers of CTCs from billions of normal blood cells.T oa ddress this challenge,w ed eveloped al ateral filter arraymicrofluidic (LFAM) device to integrate size-based separation with immunoaffinity-based CTC isolation. The LFAM device consists of as erpentine main channel, through which most of asample passes,and an arrayoflateral filters for CTC isolation. The unique device design produces at wodimensional flow, which reduces nonspecific,g eometric capture of normal cells as typically observed in vertical filters.The LFAM device was further functionalizedb yi mmobilizing antibodies that are specific to the target cells.T he resulting devices captured pancreatic cancer cells spiked in blood samples with (98.7 AE 1.2) %efficiency and were used to isolate CTCs from patients with metastatic colorectal cancer.