LPTO-04. GENERATION AND CHARACTERIZATION OF PATIENT-DERIVED PRECLINICAL MODELS FROM TUMOR CELLS ISOLATED FROM CEREBROSPINAL FLUID

BACKGROUND: CNS metastases occur in 20–50% of lung cancer patients during their disease; leptomeningeal disease (LMD) representing 5–8%, classically carries a poor prognosis with a median overall survival ranging from 1–11 months. There is a paucity of patient-derived preclinical disease models using tumor cells isolated from the CSF. Models that faithfully recapitulate the biology of CNS tumors would offer new insights into the biology of the disease as well as provide the basis for developing more effective therapy. METHODS: To create more representative preclinical models to study LMD we isolated tumor cells from CSF of 5 patients with cytologically proven LMD and implanted the cells into the subcutaneous flank of immune-compromised mice. Where possible, cell lines were also generated from PDX tissues. Models were characterized by next generation sequencing (NGS), growth rates, expression of driver oncogenes and sensitivity to small molecule inhibitors. RESULTS: To date, one PDX (LUAD-0048A) and cell line model were successfully derived from CSF samples (NSCLC patient with MET amplification) and 4 are pending. MET amplification and mRNA over-expression were confirmed by quantitative PCR in the PDX tissue and the cell line. Western blot analysis indicated that over-expressed MET was phosphorylated in both PDX tissue and cell line. These results were confirmed by immunohistochemistry. Growth of LUAD-0048A cells were unaffected by 3 MET inhibitors (crizotinib, cabozantinib, glesatinib). Similarly, MET inhibitors did not induce apoptosis in the cells. CONCLUSION: LMD represents an aggressive metastatic event in lung cancer patients. Here we were able to successfully establish a PDX from the CSF of a patient with LMD and trial targeted therapies in vivo. Translational collaborations where patients with clinical suspicion of LMD undergo CSF sampling, NGS/ctDNA analysis, and PDX modeling are crucial in improving our understanding of this metastatic compartment and investigating novel treatment paradigms.