Chondrosarcoma Co-Culture 3D Model─An Insight to Evaluate Drugs Acting on TAMs.

Chondrosarcoma (CHS), also known as malignant cartilage tumors, is the second most common bone cancer after osteosarcoma. This tumor is particularly chemo- and radioresistant, and the only therapeutic alternative is surgery with wide margins. The tumor immune microenvironment reveals an infiltration of tumor-associated macrophages (TAMs) sometimes approaching 50% of the tumor mass, mainly differentiated into M2-like phenotype and correlated with poor prognosis and metastasis. Thus, macrophage-targeting therapies could have an interest in the management of CHS. To evaluate these strategies, we propose here the development of a three-dimensional (3D) tumoroid co-culture model between two human CHS cell lines (JJ012 and CH2879) and a human leukemia monocytic cell line (THP-1) in a methylcellulose matrix. These two models were compared to the in vivo xenograft models in terms of macrophage phenotypes, proteoglycans, MMP-9, and COX-2 expression. Finally, mifamurtide, an immunomodulator acting on TAMs, was evaluated on the most in vitro relevant model: 3D co-culture CH2879 model. Our results showed that it is now possible to develop 3D models that very accurately mimic what is found in vivo with the possibility of evaluating treatments specific to a tumor cell component.