Translating Ctcs For Clinical Use: Melanoma Patient-Derived Ctcs Evolution In Xenografts

Abstract Circulating tumor cells (CTCs) are known to disseminate from primary/metastatic tumors, survive in the circulation, and develop competency to colonize distant organs. Dissecting CTC heterogeneity is therefore crucial to provide improve prognostic and diagnostic tools (concept of “liquid biopsy”). However, the clinical significance of CTC heterogeneity is still unknown. We hypothesized that melanoma patient blood-derived, lineage-negative cells (CD45-/CD34-/CD73-/CD90-/CD105-) contain melanoma cell subpopulations (Melan A+, S100+, CD146+ and NG2+ CTCs) that evolve in vivo and achieve metastatic potency when reaching an organ-specific niche. We enriched Lin-negative cells from peripheral blood of melanoma patients clinically diagnosed with or without brain metastasis (MBM) by multi-parametric flow cytometry; and analyzed CTC heterogeneity in xenografts by longitudinal capturing and interrogation at the single-cell level (DEPArrayTM platform). First, we evaluated the presence of melanoma CTC subpopulations in Lin-negative cells and developed Lin-negative murine xenograft models. Human-cell derived melanoma metastasis in xenografts confirmed that CTCs require metastasis-potentiating factors present in the Lin-negative population. Second, we performed multi-parametric flow cytometry to isolate human-derived HLA+/Melan A+/- CTCs/DTCs population from murine blood and bone marrow at T0, Tmid and Tend phases of metastasis. We interrogated the differential levels of CTCs/DTCs in HLA+/Melan A+ cell population and established their neoplastic identity by genetic profiling and the expression of melanoma markers at single-cell level. Third, we dissected longitudinal transcriptional signatures of CTCs vs DTCs in association with MBM onset. We assessed the comprehensive EMT scores of CTCs and DTCs transcriptomics and identified the pathways associated with CTC/DTCs dynamic functional states depending upon melanoma progression. Collectively, this study provide important insights to identify novel EMT-related biomarkers of MBM progression. Further elucidation of these CTC biomarkers and properties may provide novel therapeutic strategies that can be clinically useful in melanoma patients which are yet to develop MBM. Citation Format: Monika Vishnoi, Haowen N. Liu, Debasish Boral, Wei Yin, Marc L. Sprouse, Jean P. Thiery, Isabella C. Glitza, Dario Marchetti. Translating CTCs for clinical use: melanoma patient-derived CTCs evolution in xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1714. doi:10.1158/1538-7445.AM2017-1714