Ho et al. report findings from a phase 2 study of selumetinib, a MEK inhibitor, in patients with metastatic thyroid cancer in the February 14, 2013 issue of The New England Journal of Medicine. In this landmark study the authors demonstrate that treatment with selumetinib is sufficient, in some patients, to restore uptake of radioactive iodine in previously non-avid tumors. After treatment for 4 weeks, selumetinib increased RAI uptake in 12/20 patients. Eight patients had sufficient uptake to be treated with high dose of RAI, 5 of these patients had confirmed partial responses. Selumetinib was well tolerated, though 1 patient developed MDS and progression to acute leukemia 51 weeks after RAI treatment. Treatment with inhibitors of the MAPK pathway follows a long line of experimental work from the laboratory of ITOG member, Dr. James Fagin, who is Chief of Endocrinology at Memorial Sloan Kettering.