An Update on Redifferentiation Therapy for Radioiodine Refractory Thyroid Cancer.

Two-thirds of patients with advanced thyroid cancer are refractory to radioactive iodine (RAI). Inhibition of genetic drivers of thyroid cancer in the intracellular mitogen-activated protein kinase pathway, like BRAF, RAS, RET, and NTRK, results in increased expression of thyroid differentiation genes and the sodium-iodine symporter. Targeted therapies in combination with RAI result in structural decrease of metastatic lesions in 33% to 63% of patients that successfully take up RAI after redifferentiation. The true efficacy of targeted therapies with RAI remains to be proven in clinical trials against the efficacy of targeted therapies without RAI or against multi-kinase inhibitors.