Radioactive iodine therapy is often part of the standard treatment for Papillary Thyroid Carcinoma (PTC) patients. However, in many patients, tumors develop a resistance or no longer respond to radioactive iodine therapy (iodine-refractory). Several lines of evidence suggest that blocking the BRAF gene may help to re-sensitize the tumors to radioactive iodine. BRAF is a protein that plays a central role in the growth and survival of cancer cells in some types of PTC. The investigational drug GSK2118436 may work by blocking the BRAF protein in cancer cells lines and tumors that have a mutated BRAF gene.