Endocrine Abstracts

Undifferentiated/Anaplastic thyroid carcinoma (ATC) is one of the most aggressive and deadly cancers. It is characterized by loss of thyroid expression markers and no response to conventional treatments. ATC incidence is low representing <2% of all thyroid carcinomas. This, together with its high mortality, makes difficult the development of clinical trials. In our previous works, we have developed a system to culture patient-derived thyroid cancer cells (h7H) that is a good way to test new therapies. On the other hand, cell cultures don’t maintain the complete tumor environment and 3D structure of a human cancer. Orthotopic patient-derived anaplastic tumors (PDX) in mouse could provide a relevant model to study the structural disease, test best culture-selected therapies and perform precision medicine.

Methods: We designed a retrovirus construct encoding a chimera Luciferase-IRES-mCherry. A patient-derived ATC primary culture grown in h7H was infected with this retrovirus. Cells were orthotopically implanted in NOD-SCID immune deficient mice through neck surgery using an in house developed minimally disruptive approach and a Hamilton device. During the following weeks, mice were followed in vivo using an IVIS imaging system and through neck palpation, measuring neck masses with a precise calliper. A small group of mice was sacrificed 5 weeks after injection. A second group of mice were sacrificed at week 10. The last group of mice was sacrificed at week 14. At autopsy, all organs were observed and neck tissue collected for pathology analysis, staining with relevant markers and final precise dimensions.

Results: All avatar mice presented a growing neck cancer with aggressive characteristics in the luminescent assay (growing intensity, neck invasion, displacement of neck structures). The pathology revealed a cancer with similar characteristics to human ATC (high mitotic index, thyroid, nerve and muscle invasion, vascular invasion, fibrin deposition, aberrant mitotic figures, giant cells, pleomorphic nuclei and multinucleated cells). Necrosis appeared after the 10th week of evolution. p53, Ki67, TTF1 and PAX8 markers were positive as expected using conditions similar to the ones in patients’ samples.

Conclusions: Appropriate culture conditions are essential to obtain phenotype maintenance in patient-derived primary cultures. Our results showed local tumor growth and progression within the first week after cell implantation and its progression was followed along the weeks as big neck masses. We have obtained an avatar model that allows some pre-clinical studies during fourteen weeks. This model could offer a new tool for studying the biological mechanisms involved in ATC and test new therapies.