(P 296) EX VIVO SARCOMA CELL CULTURES FROM PAIRED PRIMARY, LOCAL RELAPSE AND METASTATIC SITES REVEALS PHENOTYPIC HETEROGENEITY

Objective: Ex vivo cell cultures from tumour tissue are especially of value for a disease as rare and heterogeneous as sarcoma. Furthermore, on top of the heterogeneity between sarcoma subtypes, there is intratumoural heterogeneity at the level of the primary tumour but also between primary tumour and local relapse and distant metastasis. We aimed to identify biological and functional differences between cell cultures that are derived from a single patient and even a single tumour, to assess the effects of intratumoural heterogeneity.

Methods: A single patient was selected, that suffered from a high-grade malignant peripheral nerve sheath tumour (MPNST). During the disease course, the patient relapsed with a local recurrence and later developed lung and kidney metastases. Tissue samples were collected from macroscopically different regions of the primary tumour (4 regions), the local recurrence (4 regions), the lung (1 region) and the kidney metastasis (1 region) (figure 1). Cell cultures were started from all 10 regions using a dedicated sarcoma cell culture protocol. Morphological analysis was performed using ImageJ. Growth speed was calculated based on cell doublings. A medium throughput drug screening was performed using 35 different drugs in three different concentrations. To validate results of the drug screening, five drugs were selected for GR50 analysis (Hafner M et al, - PMID: 27135972).

Results: Out of 10 tissue samples, 8 cell cultures succeeded and were used for downstream analyses. Between the cell cultures a significant difference in growth speed and morphotype was observed. A medium throughput screening showed differences in the response profiles of the cell cultures, (figure 2) and the most active compounds were confirmed in a GR50 analysis (figure 3). The cell culture from the lung metastasis clearly showed a different response profile from the cultures of the primary tumour.

Conclusion: From this data, we conclude that the 8 different primary cell cultures show unique phenotypes. The lung metastasis derived cells react differently to chemotherapy, which indicates that a model of the primary tumour is insufficient to determine treatment decisions for a patient with metastases. Furthermore, this research shows that the intratumoural heterogeneity has clinical consequences, since all cell cultures are derived from the same patient but the response to treatment differs significantly. Therefore, it is difficult and incorrect to select a cell culture from one location to represent the complexity of a primary tumour and its metastases.