GSK5182 and DN200434 enhance sodium iodide symporter function and radioiodine activity in anaplastic thyroid cancer cells in vitro, but only DN200434 (which has better in vivo pharmacokinetic profiles and biocompatibility than GSK5182) was effective in an in vivo anaplastic thyroid cancer model. This evidence concerns the gene SLC5A5 and thyroid gland undifferentiated (anaplastic) carcinoma.