Description:

This research is being done to determine the efficacy of selpercatinib to restore radioactive iodine (I-131) uptake and allow for I-131 treatment in people with RET fusion-positive radioiodine-refractory thyroid cancer. This research study involves the study drug selpercatinib in combination with standard of care treatments, I-131 and thyrotropin alfa (rhTSH).