Ex Vivo Expansion and Drug Sensitivity Profiling of Circulating Tumor Cells from Patients with Small Cell Lung Cancer

Simple Summary Small cell lung cancer (SCLC) is an overly aggressive cancer characterized by rapid growth, early metastatic spread, and consequently reducing overall survival. As cancer manifestations can differ uniquely between various types, the rapid proliferation of circulating tumor cells (CTC) originating from SCLC was an adequate sample resource to aid the headway in our drug screening technique. With biomarker detection of liquid biopsy as an emerging tool to assist decision-making in personalized cancer pharmacotherapy. In this study, we developed a rapid and reproducible system for preclinical drug testing via the use of a unique CTCs expansion protocol. The expanded CTCs from SCLC formed multiple types of tumorsphere structures and expressed SCLC-specific tumor markers. The drug sensitivity assessment gathered from in vitro expansion of CTCs was able to generate positive clinical therapeutic outcomes. Thus, SCLC patient-derived CTC spheroids are a useful resource for biomarker development and drug sensitivity assessment providing real-world therapeutic response circumstances. Small cell lung cancer (SCLC) represents one of the most aggressive malignancies among cancer types. Not only tumor sample availability is limited, but also the ability for tumor cells to rapidly acquire drug resistance are the rate-limiting bottlenecks for overall survival in current clinical settings. A liquid biopsy capable of capturing and enriching circulating tumor cells (CTCs), together with the possibility of drug screening, is a promising solution. Here, we illustrate the development of a highly efficient ex vivo CTC expansion system based on binary colloidal crystals substrate. Clinical samples were enrolled from 22 patients with SCLC in the study. The CTCs were enriched and expanded from the collected peripheral blood samples. Expanded cells were analyzed for protein expression and observed for drug sensitivity with the use of immunofluorescence and ATP titer evaluation, respectively. Successful CTC spheroid proliferation was established after 4 weeks within 82% of all the collected peripheral blood samples from enrolled patients. Upon immunofluorescence analysis, the enriched cells showed positive markers for EpCAM, TTF-1, synaptophysin and negative for CD45. Additionally, the expanded CTCs demonstrated marked heterogeneity in the expression of E-cadherin and N-cadherin. In a preliminary case series, the drug sensitivity of patient-derived CTC to cisplatin and etoposide was studied to see the correlation with the corresponding therapeutic outcome. In conclusion, our study demonstrates that it is possible to efficiently expand CTCs from SCLC within a clinically relevant time frame; the biomarker information generated from enriched CTCs can assist the selection of effective drugs and improve disease outcome.