Triple Selection Strategy for In Situ Labeling of Circulating Tumor Cells with High Purity and Viability toward Preclinical Personalized Drug Sensitivity Analysis.

Ex vivo culture of viable circulating tumor cells (CTCs) from individual patients has recently become an emerging liquid biopsy technology to investigate drug sensitivity and genomic analysis in cancer. However, it remains challenging to retrieve the CTCs with high viability and purity from cancer patients' blood using a rapid process. Here, a triple selection strategy that combines immunonegative enrichment, density gradient, and microfluidic-based size-exclusion methods is developed for in situ drug sensitivity testing. The CTC isolation chip consists of 4 independent microchannels that can evenly distribute the captured CTCs, allowing for independent in situ analysis event. The cancer cells are retrieved within 5 min with high viability (>95%), captured efficiency (78%), and high purity (99%) from 7.5 mL of blood cell mixed samples. Furthermore, the CTCs can be isolated from prostate cancer patients' blood samples and verified in situ using cancer-specific markers within 1.5 h, demonstrating the possibility to be applied to clinical practice. In situ drug sensitivity analysis demonstrates that the captured CTCs without and with cisplatin treatment for 1 day have survival rates of 87.5% and 0%, respectively. It is envisioned that this strategy may become a potential tool to identify suitable therapies prior to the treatment.