Biological sample collection to advance research and treatment: a Fight Osteosarcoma Through European Research (FOSTER) and Euro Ewing Consortium (EEC) statement.

Osteosarcoma and Ewing sarcoma are bone tumours mostly diagnosed in children, adolescents and young adults. Despite multi-modal therapy, morbidity is high and survival rates remain low, especially in the metastatic disease setting. Trials investigating targeted therapies and immunotherapies have not been ground-breaking. Better understanding of biological subgroups, the role of the tumour immune microenvironment, factors that promote metastasis and clinical biomarkers of prognosis and drug response are required to make progress. A prerequisite to achieve desired success is a thorough, systematic and clinically linked biological analysis of patient samples but disease rarity and tissue processing challenges such as logistics and infrastructure have contributed to a lack of relevant samples for clinical care and research. There is a need for a Europe-wide framework to be implemented for the adequate and minimal sampling, processing, storage and analysis of patient samples. Two international panels of scientists, clinicians and patient and parent advocates have formed the Fight Osteosarcoma Through European Research (FOSTER) consortium and the Euro Ewing Consortium (EEC). The consortia shared their expertise and institutional practices to formulate new guidelines. We report new reference standards for adequate and minimally required sampling (time points, diagnostic samples, liquid biopsy tubes), handling and biobanking to enable advanced biological studies in bone sarcoma. We describe standards for analysis and annotation to drive collaboration and data harmonisation with practical, legal and ethical considerations. This position paper provides comprehensive guidelines that should become the new standards of care that will accelerate scientific progress, promote collaboration and improve outcomes.

The in ovo CAM-assay as a xenograft model for sarcoma.

Sarcoma is a very rare disease that is heterogeneous in nature, all hampering the development of new therapies. Sarcoma patients are ideal candidates for personalized medicine after stratification, explaining the current interest in developing a reproducible and low-cost xenotransplant model for this disease. The chick chorioallantoic membrane is a natural immunodeficient host capable of sustaining grafted tissues and cells without species-specific restrictions. In addition, it is easily accessed, manipulated and imaged using optical and fluorescence stereomicroscopy. Histology further allows detailed analysis of heterotypic cellular interactions. This protocol describes in detail the in ovo grafting of the chorioallantoic membrane with fresh sarcoma-derived tumor tissues, their single cell suspensions, and permanent and transient fluorescently labeled established sarcoma cell lines (Saos-2 and SW1353). The chick survival rates are up to 75%. The model is used to study graft- (viability, Ki67 proliferation index, necrosis, infiltration) and host (fibroblast infiltration, vascular ingrowth) behavior. For localized grafting of single cell suspensions, ECM gel provides significant advantages over inert containment materials. The Ki67 proliferation index is related to the distance of the cells from the surface of the CAM and the duration of application on the CAM, the latter determining a time frame for the addition of therapeutic products.