Study schema. Vem or V, vemurafenib; C, CDX-3379; D/C, discontinue; B, research biopsy; I, tumor imaging; 124I PET-CT, iodine-124 positron emission tomography–computed tomography; 131I, radioactive iodine; IV, intravenous; mos, months; PO, orally once a day; rhTSH, recombinant human thyrotropin or thyrogen; T, serum thyroglobulin (TSH-suppressed); Wk, week.