Sequential TKI treatments for iodine-refractory differentiated thyroid carcinomas.

6092 Background: Tyrosine kinase inhibitors (TKI) are currently used to treat patients with advanced iodine-refractory differentiated thyroid cancers (DTC) but none has been approved by the FDA or the EMA until now. Sometimes, patients are treated with off-label TKI when a clinical trial is not available or in second- and third-line therapy. Methods: We hereby report the efficacy of “off-label” sorafenib and sunitinib treatments as first-, second- and third-line therapy in metastatic DTC patients from the French TUTHYREF (TUmeurs THYroidiennes REFractaires) network. Primary endpoints were progression free survival (PFS) and tumor response according to sequential TKI treatment. Secondary endpoint was organ-specific metastatic site analysis. Results: 45 patients with advanced iodine-refractory DTC treated with off-label TKI were included in this study (26 men, mean age: 62 years). 22 had papillary, 10 had follicular and 13 had poorly DTC. 24/45 patients were treated with two and 3/45 with three lines of TKI...