Abstract 3924: <i>in vitro- in vivo</i> model correlations and cross-species comparisons in osteosarcoma

Abstract Osteosarcoma (OS) is the most common primary malignant bone cancer of both humans and dogs, characterized by its high rate of metastasis. Despite decades of research, treatment strategies for OS have seen limited advancements in over 40 years. This stagnation highlights the critical need for accurate preclinical models to investigate metastasis and develop relevant therapeutic approaches. Understanding the utility and limitations of in vitro and in vivo OS models is paramount to deriving meaningful conclusions that can guide future research and inform clinical strategies. This study aims to develop an in vitro assay pipeline to investigate mechanisms of metastasis and to characterize a panel of human OS cell lines previously characterized using orthotopic amputation and intravenous murine metastasis models, allowing us to examine in vitro- in vivo correlations. Furthermore, the study seeks to characterize a diverse panel of canine OS cell lines, enabling cross-species comparisons since canine OS serves as an important model for human disease and vice versa. By correlating findings between species and in vitro and in vivo models, this investigation seeks to bridge gaps in understanding how metastatic behaviors observed in the laboratory translate to the complexities of metastasis in living organisms. The human panel includes eight patient-derived xenograft (PDX)-derived cell lines (5 primary, 3 metastatic) and two commercial OS cell lines (MG63, SJSA). The canine panel includes commercial cell line D17 and 13 primary cell lines (11 primary, 2 metastatic). The in vitro pipeline comprises six assays designed to mimic key steps of the metastatic cascade: migration (via scratch and transwell assays), invasion (using a spherical invasion assay), anchorage-independent survival (anoikis assay), and colony formation (clonogenic assay). Additionally, doubling-time will be measured to assess proliferation. Results show differences between in vivo and in vitro metastatic behavior for individual cell lines. By establishing a robust and reproducible cross-species in vitro assay pipeline, this study aims to enhance our understanding of OS metastasis and provide a platform for future mechanistic studies. The ultimate goal is to facilitate the accurate interpretation of in vitro and in vivo findings, ensuring that conclusions drawn from these models are relevant and actionable in the context of future OS research and therapeutic development. Citation Format: Emma N. Vanderboon, Geoffrey A. Wood, Courtney R. Schott. in vitro- in vivo model correlations and cross-species comparisons in osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3924.