Abstract B29: Development of CTC-derived xenograft (CDX) mouse models from early-stage non-small cell lung cancer patients
Authors: Nagaraj Suvilesh Kanve , Manjunath Yariswamy , Radhakrishnan Vijay , Avella Diego , Kimchi Eric , Staveley-O'Carroll Kevin , Li Guangfu , Kaifi Jussuf 
Published: June 2020

Abstract
Introduction: Circulating tumor cells (CTCs) are liquid biomarkers with high potential for application in precision medicine cancer care. However, no robust methods have been developed to culture CTCs from early-stage cancer patients owing to their rarity from limited disease burden and instability. Here, we describe a successful protocol to establish CTC culturing and CTC-derived xenograft (CDX) mouse models from early-stage non-small cell lung cancer (NSCLC) patients.
Methods: Surgically resected primary tumor fragments from patients with early-stage I NSCLCs were subcutaneously (s.c.) implanted to immunodeficient NOD SCID gamma (NSG) mice to generate patient-derived xenograft (PDX) models. Once palpable tumor reached a diameter of 1.5 cm, animals were euthanized and blood was collected via retro-orbital vein puncture. CTCs were enriched with OncoQuick® and cultured in vitro. These patient-derived CTCs were further characterized by immunostaining with antihuman antibodies against CK 8/18/19, Napsin, TTF-1, and CD45. Once human CTCs were confirmed, we then injected expanded CTCs s.c. and intravenous (i.v.) into naïve NSG mice to establish CDX models. Tumor growth and metastatic potential in CDX models were measured by MRI, autopsy, and histopathology.
Results: Human NSCLC primary tumor fragments implanted in NSG mice were tumorigenic at the s.c. implantation site, metastatic to distant organs, and passaged successfully to naïve NSG generations to maintain the PDX colonies. CTCs enriched from the PDX models were successfully cultured in vitro and positive for human NSCLC-specific markers (CK 8/18/19, Napsin, and TTF-1), but negative for human leukocyte marker CD45. Cultured PDX-derived CTCs that were xenografted into naïve NSG mice by s.c. and i.v. implantation demonstrated tumorigenicity and metastatic potential in CDX models.
Conclusion and Future Perspectives: This approach establishes CDX models from early-stage NSCLC patients at a high rate for personalized precision medicine. Models provide a unique opportunity to characterize rare patient-derived CTCs from curable, nonmetastatic NSCLC patients towards understanding CTC tumor biology and developing effective anticancer therapeutic strategies. Further, combined genetic and proteomic characterization of primary, PDX, and CDX tumors will be highly useful in discovering novel diagnostic/therapeutic target(s) specific to NSCLC.
Citation Format: Suvilesh Kanve Nagaraj, Yariswamy Manjunath, Vijay Radhakrishnan, Diego Avella, Eric Kimchi, Kevin Staveley-O'Carroll, Guangfu Li, Jussuf Kaifi. Development of CTC-derived xenograft (CDX) mouse models from early-stage non-small cell lung cancer patients [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B29.