Development and clinical validation of a microfluidic-based platform for CTC enrichment and downstream molecular analysis

Circulating tumor cells (CTCs) are shed from primary or metastatic tumors into the peripheral blood circulation which carry a wealth of information for cancer diagnosis, treatment and prognosis. However, most of current CTCs isolation and detection methods provide only cancer cell counting information which is far from meeting clinical needs. In addition to the numbers of CTCs, the target proteins and gene mutations carried by CTCs can also be used for clinical diagnosis, disease monitoring and therapeutic selection. In this work, we develop a novel microfluidic-based CTCs separation and enrichment platform that enables the extraction of CTCs information, including cell number, epithelial-mesenchymal transition (EMT) subtypes, protein expression levels, and target gene mutations. The platform offers a high CTCs recovery rate (> 85%), high CTCs purification (∼10 4 enrichment) and intact viable CTCs for downstream analysis. This platform can successfully enrich tumor cells from a 4 mL blood sample within 15 minutes. CTCs were detected in clinical samples from cancer patients with a detection rate of 95.8%. Furthermore, the CTCs subtypes (epithelial, mesenchymal or mix type), the expression levels of selected proteins (PD-L1, HER2, VEGF), and the target mutations in selected genes (EGFR, KRAS, BRAF) could also be directly analyzed by immunofluorescence and digital PCR for clinical utility. PD-L1 expression detected in the CTCs was consistent with the immunohistochemical results. This microfluidic-based CTCs enrichment platform and downstream molecular analysis provide a possible alternative to tissue biopsy for precision cancer management, especially for patients whose tissue biopsies are unavailable.