(P 11) ESTABLISHMENT, CHARACTERIZATION AND RESEARCH APPLICATION OF EIGHT NOVEL PATIENT-DERIVED OSTEOSARCOMA CELL LINES

Objective: There are no established effective targeted therapies to treat advanced/metastatic osteosarcoma. Access to reliable in vitro models, that accurately reflect the patient’s original tumor, capture molecular disease heterogeneity and allow rapid pre-clinical testing, are critical to identify novel therapeutics. Previous attempts at developing patient-derived osteosarcoma cell cultures have had limited success. Here, we describe our program where we generated a new panel of fully molecularly- and clinically-annotated, patient-derived osteosarcoma cell lines (OZ-SBT), expanding the global resources available for research.

Methods: Osteosarcoma patient-derived xenograft (PDX) cells were cultured in up to 24 different conditions to determine optimal culture medium, supplementation and plate-coating. Cells were validated by comparing their Single Nucleotide Polymorphism (SNP) data to whole genome sequencing profiles of original patient tumors. Tumor content was verified by immunohistochemistry. Cell lines were also transduced with CRISPR-Cas9, subjected to short- and long-term drug viability assays and injected in vivo, to determine potential research applications and allow early therapeutic testing.

Results: Our most successful culture protocol, with a success rate of 73%, allowed the in vitro expansion of eight unique osteosarcoma patient models while retaining the patients’ original tumor characteristics: the OZ-SBT panel. These models capture diverse molecular profiles, and include samples taken at diagnosis, progression and relapse (including one patient with matched samples) (all expected survival < 30%). We successfully transduced all OZ-SBT cell lines with CRISPR-cas9 and subjected them to short- and long-term drug assays, revealing known and novel drug/gene dependencies. All tested OZ-SBT cells propagated in vivo.

Conclusion: We believe our new osteosarcoma OZ-SBT cell panel, which captures distinct molecular profiles and allows a variety of research techniques, to be an important addition for the global osteosarcoma research community to expedite research. Early data illustrate their potential for exploring osteosarcoma biology and identifying potential novel therapeutic avenues, which we are currently exploring in matched in vivo models.